How fast do ironwood trees grow

Ironwood Tree: Facts, Leaves, Flowers, Bark (Pictures)

The ironwood tree (Ostrya virginiana) is a small deciduous understory tree. It is identified by its birch-like leaves, light brown shaggy bark, and yellowish-green flower clusters. Ironwood trees are attractive in the landscape with a pyramidal, rounded crown and their ability to grow in almost any location. As an understory tree, the ironwood performs well in deeply shaded conditions, and it also grows just as well in full sun. 

Also called the American Hop Hornbeam, the ironwood is known for its incredibly robust, strong timber resulting from its slow growth. The attractive cold-hardy tree grows well on sloped areas, as well as rocky forests, compacted clay soil, and is relatively resistant to drought.

This article is a complete identification guide to the ironwood tree. Descriptions and pictures of ironwood leaves, bark, flowers, and fruit will help you identify it in the landscape. If you decide this tree is perfect for your garden landscape, there is a handy care guide at the end of the article.

Ironwood Tree (Ostrya virginiana) Facts

American hophornbeam (Ostrya virginiana)

Ironwood is classed as a small to medium-sized ornamental tree belonging to the genus Ostrya in the birch family Betulaceae. The ironwood tree grows 20 to 40 ft. (6 – 12 m) tall and up to 30 ft. (9 m) wide. It has a trunk diameter of up to 10” (25 cm), covered in peeling, shaggy bark. 

Ironwood trees grow slowly, averaging around 12” (30 cm) or less per year. It will take 15 years to grow 10 to 15 ft. (3 – 4.5 m) tall. Young ironwoods have a typical pyramidal shape that gradually becomes more oval and rounded as it matures. 

Ironwood trees thrive in USDA zones 3 to 9. The cold-hardy tree performs well in all growing conditions — from deep shade to full sun. As long as the soil is well-drained and not prone to flooding, ironwoods grow well in most soils.

An attractive feature of ironwood trees is their horizontal, drooping branches covered in serrated, ovate leaves. Immature trees have somewhat fuzzy branches that become smoother and gray as the tree matures. 

The slow growth of ironwood trees is why the timber is so robust. Ironwood has one of the hardest woods of all the native North American trees. It’s harder than maple, white oak, hickory, elm, and birch trees. Because of this, the wood is used for making tool handles, fence posts, and mallets. 

Other common names for ironwood tree refer to the tree’s strength or growth features. For example, the names American hophornbeam and wooly hop hornbeam refer to the hop-like fruit that the tree produces after flowering. It is also sometimes referred to as leverwood or hardhack.

Being a member of the birch family Betulaceae, the ironwood tree shares characteristics of birch and elm trees. Its leaves are lance-shaped with serrated margins like birch trees. Additionally, its spreading pyramidal to oval shape gives it the appearance of elm trees. However, ironwood trees are significantly smaller than elm and birch trees.

Ironwood Tree Flowers

Ironwood tree flowers

Flowers on ironwood trees are in the form of dangling catkins — yellowish-green or reddish-brown drooping clusters. The tubular clusters measure around 3” (75 mm) long and grow in groups of up to four. Ironwood is a monoecious tree, meaning male and female flowers appear on the same tree.

Male ironwood flowers are yellowish-brown and appear as scaly bracketed spikes drooping from branches. On the other hand, female ironwood flowers are pale green flowering spikes standing erect on new twigs. 

A feature of ironwood tree flowers is that the male catkins persist on the tree throughout winter. 

Ironwood Tree Leaves

Ironwood tree leaves

Leaves on ironwood trees are light green, lanceolate shaped with double serrated margins and a fine fuzzy texture on the upper side. The oval-elliptic pointed leaves measure 3” to 6” (75 – 150 mm) long and 2” (50 mm) wide. The ironwood leaves are characterized by deep parallel ridges from the midrib to the edge.

Ironwood tree leaves are simple leaves that grow alternately on thin twigs. The pointed lance-shaped blades tend to be small further up the canopy.

Ironwood leaves in autumn

It’s easy to mistake ironwood leaves for birch tree leaves. However, ironwood leaves turn an insignificant yellow color in the fall compared to vibrant golden-yellow birch leaves. Additionally, ironwood leaves usually drop earlier than birch tree leaves. 

Ironwood Tree Bark

Ironwood tree bark

The bark covering the ironwood tree trunk is light brown and shaggy that develops into rectangular plates. The bark on young ironwood trees is relatively smooth with several lenticels. However, in time the bark becomes scaly and peels easily from the tree. Mature ironwood trees have grayish-brown loose scaly plates. 

Ironwood Tree Seeds (Fruit)

Ironwood tree fruit

The ironwood tree is identified by its hop-like fruit — clusters of seed-bearing pods of papery sacs, each containing a tiny, oval nutlet. The pendulous clusters of papery enclosures grow between 1” and 2” (25 to 50 mm) long. The seed clusters develop in summer and persist on the tree through winter. 

Ironwood Tree Identification

The identifiable features of the ironwood tree are its light green, pointed, lance-shaped leaves with doubly-serrated margins, dangling copper-brown colored hop-like fruits, and light to dark brown shaggy, narrow strips of bark. Ironwood is a relatively small tree in a landscape compared to birch and elm trees. 

Ironwood Trees in the Landscape

Ironwood tree is an attractive shade-tolerant tree, making it ideal for growing as an understory tree. The ironwood tree performs well in various moisture and soil conditions but grows best in well-drained soil in part sun. In the landscape, ironwood has a rounded canopy and slender, rough trunk. 

Ironwood is an excellent tree to grow in urban and residential landscapes. The hardy tree copes well with various urban conditions, like pollution and compacted soils. This is one reason why it’s a popular street tree. In addition, the tree’s relatively small size makes it ideal for residential gardens to grow as a shade tree in a backyard or around patios, especially where space is restricted.

One reason to consider growing an ironwood tree is that it requires little pruning to maintain its shape. In addition, its robust branching system means that it’s resistant to breakage in high winds or under heavy ice or snow.  

Where to Plant Ironwood Tree

Ironwood trees perform best planted in full sun to partial shade. However, as an attractive upright understory tree, it will also grow well in deep shade. Ironwoods also adapt well to varying soil conditions. Therefore, you can plant it in dry, gravelly soil or heavily compacted clay soil. 

When planting an ironwood tree, the most critical growing consideration is that the soil drains well. Ostrya virginiana doesn’t like soggy roots, and it won’t grow well in areas prone to flooding.  

Another consideration is its tolerance of salty conditions. Ironwood is intolerant of salt, so it shouldn’t be planted near roads that are heavily salted in the winter.

How to Plant Ironwood Tree

It’s best to plant ironwood as a nursery tree that has grown in a container. Ironwood trees are notoriously slow growers, and planting a tree from a nursery gives you a great head start. 

To plant a potted Ostrya virginiana, prepare the location by digging a hole as deep as the root ball but three times as wide. Next, remove the tree from its pot and loosen the roots as much as possible. Then set it in the center of the hole, ensuring that the part where the trunk broadens to the roots (the tree flare) is slightly above ground level.

The next step is to half fill the hole with native soil, tamping the ground firmly as you backfill the spot. Then thoroughly water the roots to hydrate them and eliminate air pockets. Lastly, fill the hole up to the soil line, pressing down as you go.  

After planting the ironwood tree, thoroughly water the ground and put a 2” to 3” (5 – 7.5 cm) layer of mulch over the root area. Mulching a newly-planted tree helps lock in moisture, prevents evaporation, and stops weeds from growing through. 

Ironwood Tree (Ostrya virginiana) Care Guide

It’s easy to care for ironwood trees, as they can adapt to various environmental conditions. However, the iron-hard trees require specific care for the best results, especially during the first years after planting. On the other hand, well-established ironwood trees tolerate drought and require little maintenance.

How to Water Ironwood Trees

Established ironwood trees don’t require much watering for healthy growth. Typically, you can give the tree around 1” (25 mm) of water per week, as long as the top layer of soil dries out between watering. However, ironwood trees are relatively drought-tolerant trees and will withstand periods of dry conditions.  

Regular watering is critical for the first two years after planting an ironwood tree. Regular root hydration helps to develop a healthy, robust root system. During the first two years, deeply water the tree twice a week, from spring through summer. In addition, it may be necessary to water the tree more frequently especially during dry weather. 

Ironwood Tree Fertilization

Ironwood trees can benefit from regular fertilization to keep them healthy and prevent pest damage — however, it’s not usually required. You can use a nitrogen-rich fertilizer to promote green leafy growth. It’s essential to avoid excessive nitrogen in the soil as this could affect flower and seed production. 

Generally, there is no need to amend the soil or apply fertilizer to newly-planted ironwood trees. This is because the salts in the fertilizer compound could burn the roots. 

It’s good to note that ironwood trees typically grow well in average soil without adding fertilizers. The best advice is to work in some rotted manure or organic compost to the root area in spring. However, if you decide the tree requires additional nutrients, get a soil test done first to determine the type of tree fertilizer to use. 

How to Prune Ironwood

Ironwood doesn’t require much pruning to develop a strong branching structure. While the tree is relatively young, you can remove some lateral branches to form a dominant central trunk. This is especially necessary with some ironwood trees that grow multiple stems. However, an established ironwood tree doesn’t need regular pruning.

As part of regular tree maintenance, it’s a good idea to inspect ironwoods annually in late fall after the leaves have dropped. Look for broken, dead, or diseased limbs, as well as branches that are rubbing together. You can remove those branches to encourage healthy growth and prevent disease. 

Ironwood Propagation

Although stem cuttings are the most common method to propagate shrubs and trees, seed propagation is the preferred way to grow an ironwood tree. Ironwood seeds require warm stratification and cold stratification to germinate successfully. 

It’s good to note that when handling ironwood seeds, you should wear gloves. The ornamental tree is also called the itchy tree because the seed clusters can cause itchy fingers — like after handling fiberglass insulation without protection.

How to Grow Ironwood Tree From Seed

Ironwood trees are relatively easy to grow from seed by sowing them directly in the ground in early fall. 

Alternatively, you can collect the ripe seeds between late summer and early fall and dry them. 

Ironwood seeds require 60 days of warm stratification followed by 120-140 days of cold stratification. This is necessary for successful germination. To grow Ostrya virginiana from seed, this is what you should do: 

  • Submerge the seeds in a jar of boiling water and leave them to soak for 24 hours.
  • Put the seeds in a sealable (zip-lock) plastic bag filled with damp sphagnum moss.  
  • Put the seeds in a warm place that is between 68°F and 86°F (20°C – 30°C) for 60 days. Then, regularly check the seeds for mold and keep the soil slightly damp.
  • After that, place the bag in a cool place that is 39°F to 41°F (4°C – 5°C) (like your refrigerator) for 120 days.

After stratifying the seeds, you can put the seeds in small pots filled with damp, well-draining potting soil to germinate using standard procedures. 

How to Grow Ironwood Seedlings

To germinate stratified ironwood seeds, prepare a seed soil mix from 3 parts peat moss and one part perlite. Fill small individual pots with the potting mix and mist to moisten. Next, put a seed in each pot, about 0.25” (6 mm) under the surface, cover with plastic, and put in a bright, warm place out of direct sunlight.

Once the seeds germinate after a few weeks, place them in a brighter location where they get around 12 hours of light daily. After one month, you will need to transfer the ironwood seedlings to a larger pot. Then, you can plant them outdoors in the ground when the seedlings have grown about 15” to 20” (40 – 50 cm) tall.

Pests Affecting Ironwood Growth

A benefit of growing an ornamental ironwood tree in the landscape is that it is relatively pest-free. Healthy trees rarely suffer any damage from common tree bugs like aphids, scale insects, or leaf borers. 

The only significant pest to affect ironwood tree leaves is the two-lined chestnut borer (Agrilus bilineatus). This slender black beetle can live and feed on the inner bark of ironwood trees. The beetle activity can result in defoliation. However, the best way to prevent this is to water the ironwood well during drought periods. 

Diseases Affecting Ironwood Tree Growth

Ironwood is a robust, hardy tree, and typical tree diseases rarely affect its growth. Sometimes, canker diseases can cause individual branches to die back. However, it’s usually possible to avoid this by preventing the tree from getting stressed. So, water it well during dry weather. 

Occasionally, foliar diseases like powdery mildew, leaf blister, and leaf spots can affect the tree leaves. However, they never significantly harm the tree’s health, and generally, there is no need to control them.

Related articles:

  • Small Flowering Trees
  • Small or Dwarf Evergreen Trees
  • Small Trees for Landscaping Small Spaces

Read Next

Poplar Trees: Types, Bark, Leaves - Identification (With Pictures)

Types of Redbud Trees: Eastern, Western, Chinese, and More (Pictures)

32 Dwarf Conifers: Dwarf Pine, Spruce, Cypress, Juniper & Yew (Pictures)

Loblolly Pine: Cones, Needles, Bark (With Pictures) - Identification and Care

How to Grow an Ironwood Tree: Mother of the Sonoran Desert

I’m super excited to be writing about this particular species because it is my absolute favorite tree. I fell in love with desert ironwood (Olneya tesota) at the very beginning of my landscaping career. I was managing a large property that had just one on site, a big specimen located in a wide expanse of lawn. It was off-season, so at first it was just one of what seemed like thousands of trees I had to study and learn.

The Sonoran Desert, home of the ironwood tree, at night. Foreground: Skeleton of a self-preserved ironwood tree.

The first time I saw it in-bloom, I didn’t recognize it. I saw it through the windshield of my truck as I was parking, and for a second I thought I was in the wrong place. As I walked toward it, I figured out it had bloomed, and I was excited. It looked so beautiful from my vantage point, and the closer I walked, the prettier it became.

The first time I saw an ironwood tree bloom, I was mesmerized.  The gauzy lavender cloud of flowers appears to bathe everything around it in a soft purple glow. “Olneya tesota” by Matt Lavin is licensed under CC BY-SA 2. 0

The entire canopy was hidden underneath what looked like a shimmery cloud of this incredible shade of pale purple with a hint of dark pink. Instead of being on the limbs, the blooms looked almost like they were hovering in the air around them. There was movement. There was dimension. It was the most gorgeous thing I’d ever seen, and I fell in love.

The more I learned about this enigmatic tree, the more I loved it. So I’m excited to share the desert ironwood with you because, being endemic to the desert southwest, there’s a good chance you don’t know about it. And to truly appreciate this tree, we must understand not only its individual history, but also the history of its habitat: the Sonoran Desert.

How the Sonoran Desert Became Home to the Ironwood Tree

This map shows all the deserts in the US. There are four main, but they have been broken out into smaller parts. 

1 – 8. Great Basin Desert 9. Mojave Desert. 10 and 11. Sonoran Desert — where ironwood trees occur naturally. 12. Chihuahuan Desert

Desert ecoregions of North America as defined by the Commission for Environmental Cooperation.” By Joe Roe / This file is licensed under the Creative Commons Attribution-Share Alike 4.0 International license.

The Sonoran Desert (one of only four North American deserts, all of which are in the far western third of the US) likely began forming in the Miocene Epoch of the Neogene Period. Approximately 23- to 5-million years ago, the already-formed Sierra Madres and Rocky Mountains were pushed high enough to disturb atmospheric flow. For the first time, tropical moisture from both the Gulf of Mexico and the Pacific Ocean was impeded by the two mountain ranges, thus drying out the area of land between them.

Also key to the Sonoran’s present-day topography is the state of Baja California in Mexico. This piece of land used to be part of Mexico’s mainland but was dislodged due to seismic activity along the San Andreas fault. After it broke off, it floated over and eventually attached itself to the bottom of California, forming the Baja Peninsula and the Gulf of California.

The ironwood tree was first described by botanist Asa Gray in his 1854 collection Plantae Novae Thurberianae. He named it Olneya tesota after his friend and fellow botanist Stephen Thayer Olney.

Shortly after the beginning of the current interglacial (the Holocene), about 11,000 years ago, plant life like brittlebush and saguaro cacti (Sonoran Desert mainstays) began showing up in the area where the Sonoran’s development had been stymied by more Ice Ages, glaciers, then the subsequent melting of those glaciers. Despite the early return of these desert plants, the area remained heavily populated with woodland plants for another 2,000 years. Those plants eventually retreated upslope, and the Sonoran Desert’s latest iteration, the one we still know today, was complete.

It was thought that Olneya tesota formed concurrently with the Sonoran beginning in the mid-Miocene Epoch but some paleogeological findings indicate that may not have happened until the mid- to late-Holocene Epoch (the current epoch).

The Significance of the Ironwood’s Role in the Sonoran Desert

A relatively young and small ironwood tree as it occurs in nature. The “ironwood” common name is a reference to its incredibly dense wood. Because of its density, it is very hard, heavy, and does not float.

“Not sea worthy wood!” by Take A Hike Arizona is licensed under CC BY-NC-ND 2.0

The Sonoran Desert is teeming with life, rich in diversity, the most diverse of any North American desert. At least 60 species of mammal (including the country’s only Jaguar population), 350 species of bird, 100 different reptiles, 20 amphibians, and another 30 species of native fish all make their homes here. Additionally, 2,000 different species of plants, flowers, trees, and cacti all thrive in the Sonoran Desert, which is the most of any desert in the entire world.

In this biodiverse ecosystem, the ironwood has responsibilities and plays an important role in the successful continuation of life:

  • As a keystone species: keystone species are those whose presence is needed to hold the entire system together; without them, the system would fail.
  • As an indicator species: indicator species are used as a barometer by which certain environmental conditions are measured; they can tell us that something has changed or is going to change in the environment.

The seed pods of this tree have historically been an important source of food for both animal and human alike. 

  • As a nurse plant: perhaps most impactful of all its responsibilities. Ironwoods are “nurse plants,” meaning they’re important to the survival of other life forms; in this case, about 500 species rely on the ironwood for their continued existence. Ironwoods provide a place of refuge for animals being hunted, they provide shelter, they’re a source of food, and their dense, low canopies create a microclimate around them that’s about 15-degrees cooler. More than 250 different species have been documented starting their growth in the nutrient-rich soil under an ironwood tree.

Before Planting: The Pertinent Details

Before getting too excited, or even going to the nursery, you want to ensure whatever species you’re considering is right for you. Not only that, but that you’re right for it. It’s important that you both be happy, and that you both possess the wherewithal to facilitate that happiness.

Ironwoods are easy to grow and very low-maintenance, but they have a couple of personality quirks that could be deal-breakers. So here’s a quick rundown:

  • Ironwoods typically reach a height of anywhere from 25- to 45-feet
  • They’re members of the pea family, therefore, they’re leguminous and produce seed pods
  • Trunk diameter can get up to 24″ across
  • They’re exceptionally slow growers (I cannot emphasize this point enough; they are the slowest-growing tree I’ve ever worked with, by far)
  • Ironwoods like to live long lives, sometimes making it to 1,000 or even 1,500 years old
  • They’re known for their dense, heavy wood (hence the common name of “ironwood”)
  • They have thorns — a pair of them at the base of every leaf — making pruning a bit of a tough job

Without any trimming at all, an ironwood takes on the shape of an oversized, overgrown shrub. In ornamental applications, natural-style pruning is desirable. 

  • Speaking of pruning, they require a lot of it to look tip-top (more on that later)
  • The bloom period is short, usually 10-18 days, sometime between April and June
  • They’re evergreen, but will drop its leaves if too cold or too thirsty
  • They love very coarse, very porous soil; if your existing soil is neither coarse nor porous, it needs to be amended before planting
  • Ironwoods are hardy to 20-degrees fahrenheit (they don’t like temperatures below 20-degrees)

How to Plant and Grow an Ironwood Tree

The flowers of an ironwood tree, shot at close-up range. The tree blooms for 10-18 days once per year between April and June.

Ironwoods can be started from seed, right out of the pods taken from an ironwood tree. But just because they can, doesn’t mean they should.

Buy a nursery specimen

Waiting for seeds will set you back a boatload of years; it’ll take you up to ten years to grow a specimen roughly the same size as one you could pick up at a nursery tomorrow. It could be 15 years or more before a specimen grown from seed flowers or produces fruit.

15-gallon vs. 24″ box (hint: get the 15)

My recommendation is to skip the starting-from-seed on this species and support your local nursery industry by buying from them. Typical install size is 24″-box or 15-gallon-bucket. The 15-gallon size container plants actually adjust faster than bigger specimens, plus, there isn’t usually that much difference in size. In this case, I’d save the money and go with the 15-gallon size.

When: plant in October

Where you plant an ironwood tree is just as important as how you plant it, and both are just as important as when. In this case, October is the best time to plant your new ironwood. The temperatures below ground are still nice and warm from summer but already much cooler above ground, which creates excellent conditions for planting. Plus, October is early enough to give the tree time to settle in a bit before cold winter temperatures.

Where: front and center

Ironwoods don’t lend themselves well to being tucked back into a corner or used as filler to take up space.  Their job in nature may be to take care of everyone and everything else, but in an ornamental application, they like the starring role, and they play it well.

If you can stay on top of pruning and are willing to outfit it with some low-voltage landscape lighting, give it a wide-open space where it can shine and be the undisputed statement piece. With careful, detailed, selective pruning, ironwoods are architectural masterpieces. In the low light of fading sun, they create interesting silhouettes, and uplit with soft lighting, they look rich and luxurious.

How: about the same as usual (but mind the roots!)

Prepare a hole that’s roughly the same depth as the root ball, or just a hair shallower (some of the root ball sticking out of the ground is OK), and two or three times as wide. As you dig, turn the soil and break apart any clumps.

The soil should be coarse and porous to allow for maximum water and air circulation throughout the root system. If the soil needs to be amended to accomplish this, now is the time to do it.

From container to ground

Looking up into the canopy of an ironwood tree. When used ornamentally, structural pruning is required to remove cross branches.

There are no secret tricks to getting the tree from the nursery bucket to the hole in the ground. One way uses a straight-edge to slice off the bottom of the container, then cut up the sides and pull it away while the tree is in the hole. Depending on how worried you may or may not be about damaging roots, this method may or may not work for you.

Another method involves turning the container on its side, shimmying the container off the plant, and rolling the plant into the hole. Not always easy to do and keep the root ball together at the same time.

My experience has been that the easiest way is to simply leave the container and tree standing upright, and give the container a few knocks around the outside to loosen the root ball away from the container walls. Then grab low on the tree trunk and give a little tug to make sure it’s loose, and, assuming it is, just go ahead and pull the whole root ball up and out. Ideally, do this right next to your hole, so you can pull up and out of the container and then set it down into the hole in one fluid motion.

Roots: touch them or leave them alone?

Roots that are white in color, not completely dried out, and stay together when touched are still alive and relatively healthy, despite being bound. 

There are at least two schools of thought on how to treat the roots when planting: do not disturb them at all no matter what, or slice into them with a straight edge. Neither method should be used absolutely. Something like this should always be species-specific. Educate yourself on the preferences of the species you’re planting so you know which method typically gets the best results. Even armed with that knowledge, do a visual inspection.

Root inspection
  • Pull the root ball out of the container, set it on the ground, and give it a thorough inspection. You’re looking for the appearance of healthy roots versus damaged roots.
  • If the roots are thick and white, they’re new and healthy.
  • If they’re stringier and darker brown in color, and growing around the root ball, use your fingers to lightly disturb them and see how they respond.
  • If they fall apart easily with a light touch, that section of the root system is useless. But..!
  • *Look for a point above it where there’s new healthy growth that doesn’t come apart. As long as you have a good amount of healthy roots still there, the plant should be fine.
  • To be extra-sure, and to give the tree a little boost, water in with SuperThrive after planting.

In the specific case of ironwoods, they have two kinds of roots: a shallow, spreading root system and a deep taproot. The shallow part is outfitted with nodules that deliver nitrogen to the soil, and the deep taproot goes down and finds water. If a visual inspection doesn’t do the trick, touch the roots only lightly to test their structural integrity. As long as they’re not coming apart in your hand at your touch, you should be ok.

Roots that are brown, dry and brittle to the touch, and that disintegrate or fall apart when lightly disturbed are dead and cannot be planted. 

Once you’ve checked the roots and have your root ball in the hole, use one hand to hold the tree straight upright and start backfilling the hole with the other hand. Stop every few scoops and tamp down to release any air pockets. When you’re done backfilling, a small lip of root ball should be sticking up just a smidge higher than the ground.

After-planting checklist

Once the hole is backfilled, there are a few more tasks to complete. Follow this after-planting checklist to make sure you don’t forget anything:

  1. Remove the nursery stake (if applicable)
  2. Restake using proper methodology (if needed)
  3. Water the tree in, giving it a deep soaking
  4. Put a couple of capfuls of SuperThrive into a full 1-gallon-jug of distilled water, shake to incorporate thoroughly, then pour the entire gallon jug over the planting area
  5. If adding to an irrigation system, place the drip emitter and test from the clock to make sure it’s working
  6. Top-dress the planting area with a 2-inch layer of mulch

Ironwood Tree Maintenance

Ironwoods are “high” maintenance the first year they’re establishing (relative to the rest of their lives) and virtually hands-off after that, apart from pruning. Watering and pruning are the only two things you’ll have to consider.


It’s not uncommon for the desiccated trunks of old ironwoods to remain standing for hundreds of years. They contain a toxin that makes the dense wood virtually non-biodegradable. 

The first year: dig a berm all away around the tree, about two feet out from the trunk. Water the tree every few days, and fill in the berm once per week.

After a year: the berm should be moved out as the tree grows. Give the tree a deep soak once every two to four weeks. If this doesn’t appear to be enough, you can increase, but  no more than once per week. Every time you water, fill in the berm.

Two years and older: continue to move the berm out once a year and fill with each watering. This encourages deeper root growth. Once the tree has doubled in size, the water can be cut back more.

Note: Ironwood trees are incredibly drought-resistant, and do not like too much water. Be attentive and keep an eye out for signs of overwatering.


Once the tree is about three years old, start implementing a pruning schedule. The key to a really good-looking ironwood is in the pruning. Ironwood trees are amazing, but left to grow naturally can look a bit disheveled and messy. The more thoughtful and deliberate you are with your approach, the bigger the payoff will be.

The video below provides excellent instruction on how to properly prune a multi-trunk desert tree.

Multi-trunk vs. single trunk

Ironwoods are naturally multi-trunked, and there’s no reason to change that. The multi-trunk design is perfect for their upward and outward (and then downward) growing pattern. You want to let the canopy be as natural as possible, and because it naturally wants to spread out, a single trunk just isn’t practical or visually pleasing under all that spread.

Go slow, be selective

If you’re going to hire professional tree trimmers to maintain your ironwood, then you don’t really have to worry about this. But it’s something you can learn to do, and you might find that the activity is satisfying and fulfilling in ways you didn’t expect. If you do it yourself, it’s OK to go slow. Take a step back, look at the tree, and notice where your eyes fall first. What it notices first. Is it noticing something nice that should stay or something unsightly that needs to go?

Ironwoods have a naturally pleasing structure. Just lift from the bottom, create some air and space between the limbs, and follow their natural shape. You’ll do just fine.


Adding uplights to trees is a fast and easy way to add instant visual interest to your landscaping. It looks expensive, but it’s not.

Ironwoods don’t have issues with pests or diseases, so the last thing we’ll talk about is lighting. Lighting is, of course, always an optional upgrade, not necessary for the health of the plant. It doesn’t hurt it, and it doesn’t add to it. It’s just a matter of personal aesthetics.

Ironwood trees happen to have a structure that’s perfect for strategically placed uplights. It doesn’t matter what style your overall design is, or if the ironwood is the only thing in your yard, it creates such a stunning effect that’s lovely to look at.

Many low-voltage systems these days are solar-powered or plug-in, manage to stay discreet during the daylight hours, and are reasonably priced.

A dead ironwood tree, perhaps lamenting the loss of its beautiful blooms, and in so doing failing to see the beauty it still possesses. 

If you happen to live in the desert southwest and have never worked with an ironwood, I hope you give this slow and steady beauty a shot. Even if you’re not in the southwest but within zones 8-11, this could be a fun experiment.

The bloom cycle may be ephemeral, but it’s an experience millions of years in the making that stays with you forever. And maybe it’s a good reminder that we should always be willing to look deeper, and find the beauty where we may have missed it before.

Persian parrotia, ironwood / Tree species of the world


Grows in the Caucasus in the Talysh mountains. Forms pure and mixed stands in the lower belt up to 400–600 m above sea level. Individual trees are found at much higher altitudes (1000–1200 m). It reaches its best development on fresh, powerful soils, well supplied with moisture. On dry soils, it greatly slows down growth; it does not withstand waterlogged and saline soils. It belongs to shade-tolerant breeds, it is thermophilic, but in the area it is frost-resistant everywhere.


Deciduous tree up to 25 m high, sometimes forming tall shrubs. The trunk is up to 40–50 cm in diameter. Young shoots are first pubescent and greenish, then bare and brownish. numerous branches, which often grow together. The arrangement of the leaves is alternate. The leaves are simple, 4–13 cm long and 3–8 cm wide, leathery, asymmetrical, from ovate and obovate to elliptical, pointed at the apex and oblique, weakly heart-shaped or wedge-shaped at the base, irregularly obtuse-triangular-toothed at the edges. In autumn they acquire a bronze-brown color and remain on the trees for a long time. The flowers are bisexual, petalless and small, collected 2-5 in axillary heads or buds, surrounded by brownish-felt bracts. Stamens 6-7 with dust particles brightly colored in red and purple tones. The ovary is semi-inferior, two-celled with two columns. Blooms in February-March before the leaves open. The fruit is a two-celled, two-seeded, woody capsule up to 16 mm long. Seeds are oblong-ovate, sharp, dark brown shiny with two clear white scars at the base. The fruits ripen in September. The average weight of 1,000 seeds is 50.5 grams. In 1 kg from 17.8 to 21.5 thousand seeds. The iron tree grows slowly, with an average annual growth of about 20–30 cm in height, and 2–3 mm in diameter. At the age of 50–60 years, in good conditions, the height reaches no more than 15 m and a diameter of 25–30 cm. It begins to bear fruit from the age of 10–12, reaching normal fruiting at 25–30 years. Harvest years are observed in 1–2 years. One tree at the age of 80–100 years produces up to 2 kg of seeds in harvest years. Trees that stand in open places bear fruit well, and in plantations - those that receive full crown coverage. Seeds have good germination and germinate quickly. When ripe, the boxes crack, and the seeds from them fly out at a distance of 15 m or more from the crown. The iron tree reproduces well vegetatively, cuttings, layering, shoots. In good growing conditions, there are from 60,000 to 250,000 specimens of coppice ironwood per hectare. It lives up to 200 years. The root system of the iron tree is highly branched and extends over long distances, deepens to 150–180 cm on light soils, which determines its value for protective afforestation. Beautiful foliage, flowering, original branching and a peculiar crown give the iron tree a high decorative effect and allow it to be used in landscaping. Ironwood tolerates shearing and shaping well, which makes it valuable for creating hedges and various sheared forms. Listed in the Red Book.


Without division into heartwood and sapwood, pinkish in color, with a brown tint, turns brown in the light. The outer layers of wood are painted lighter than the central ones. The annual layers are not always sufficiently distinguishable; there are false growth rings. Wood consists of vessels, fibrous tracheids, cord and ray parenchyma. The wood is sparsely vascular, the vessels in their arrangement do not form any pattern. Density at 15% humidity 0.77 g/cm³, at 12% 0.75 g/cm³. The wood is homogeneous and very dense.


Shrinkage ratios: radial - 0.032%, tangential - 0.058%.


At 12% moisture compressive strength along the grain 593×10 5 Pa, static bending 1411×10 5 Pa, shearing 145×10 5 Pa.



Technological properties

Wood is processed with cutting tools and finished.


It is used in the manufacture of weaving shuttles, used as a raw material for high-quality furniture and for finishing work.

Show all types of wood starting with the Russian letter “P”

Other trees of the Hamamelidaceae family
  • Plants with truly amazing properties can be seen in the wild. For example, in any part of the world you can find a group of trees, the fibers of which are incredibly durable. This feature is extremely rare, in connection with this, such plants are treated with particular interest.

    If firearms are fired at the bark of such an outlandish plant, it can withstand a bullet. Its qualities are similar to cast iron: it is highly durable and at the same time rust does not appear on it. It is thanks to these unusual properties that such plants were listed in the Red Book under the name "Iron Tree".


    • 1 What is an iron tree
    • 2 Types of iron trees with a photo
      • 2.1 Schmidt birch
      • 2.2 ARGNIA Polya
      • 2.3 Parroti Persian (Temir-Agach)
      • 2.4 Other species
    • 3 features of wood
    • 4 Application

    What is the Iron Tree


    with a long time as people worry, why some worries some kind of people. trees are incredibly durable. And thanks to what they are called "Iron Tree". And also how the wood of adult plants is used, and for what properties this breed is valued very dearly.

    In almost every country you can meet the "root" tree, the structure of which is very similar to iron, while it has the properties of a metal. Such plants are most often among the centenarians, since the growth of wood fibers is extremely slow. From such trees a valuable material is obtained, which has found application in the transport and construction areas.

    At first glance at such a heavy-duty tree, it is unlikely that it will be possible to find at least some differences from its fellows. Their features include very slow development and high life expectancy. Almost each of these specimens lives up to 200 years and this is not the limit. You can meet iron trees whose age exceeds 500 years. As a rule, the age of a tree is determined by annual rings on the cut of the trunk. However, in such unusual plants, annual rings are almost invisible.

    Ironwood timber. Hyrcanian National Park | Film Studio Aves

    Watch this video on YouTube

    Types of iron trees from the photo

    In every corner of the planet Earth you can find amazing trees with the properties of metal. The term "iron trees" combines many plants with similar properties. On the territory of Russia, you can also find a similar high-strength tree.

    Schmidt's birch

    Such a long-lived tree grows in Primorye of Russia. It was named after F. B. Schmidt, who was a scientist. In terms of quality, this amazing tree can be compared with a bulletproof vest. This is the strength of its wood.

    The height of such a birch is about 25 meters, while its trunk reaches a diameter of about 0.8 meters. Such a majestic tree has an oval shape, and its trunk is covered with grayish creamy bark. Intense green leaf blades have short petioles.

    This "iron giant" is most widely distributed in the Asian part of the planet Earth. At the same time, people have found its use in various fields. For example, in Korea, China and Japan, such a plant is used to treat acute and chronic forms of eczema, wounds and lichen, and preparations with a powerful choleretic effect are also prepared on its basis.

    Argan prickly

    A similar plant can be seen in Africa. At the same time, it was most widely used in the southwestern part of Algeria and Moroccan territory. To date, the number of such plants is more than two million. At the same time, it plays an important role in the life of local Berbers.

    Branches from this plant are used to build the frame of the hut, making it very stable. They are also used as fuel for heating. The leaves can be used as feed for livestock. The locals also use prickly argan as a source of food.

    The diameter of the crown can be up to 15 meters, while it is located at a height of about 10 meters. The roots are powerful and well developed, looking for moisture, they can penetrate deep into the soil up to 30 meters. Some animals feed on the leaves of plants. And in order to protect themselves from them, nature “armed” the plant with needles pointed at the tips, which are located on the branches.

    Persian parrotia (Temir-agach)

    This plant also belongs to the "iron trees", and it stands out for its unusual wood, which is harder than steel. It is most widely used in Africa and Iran, and it can also be seen in Azerbaijan. This tree looks especially impressive during flowering, when its branches are covered with beautiful flowers.

    In its homeland, the tree is thermophilic. But in general, it is able to tolerate fairly low temperatures - up to minus 25 degrees. The height of an adult parrotia can be compared with the height of a ten-story building. The life expectancy of this plant can often reach up to 200 years or even more. The forests consisting of Persian parrotia are among the UNESCO World Heritage Sites.

    This plant can be used to create a green hedge that is considered impenetrable. In the distant past, the wood of this tree was used as a melee weapon during wars. And today it can be used to make windows and floors.

    Other species

    Other plants that can be found on other continents also belong to the “iron trees” group, for example:

    • Christmas;
    • mezuya;
    • sideroccilone;
    • southern frame;
    • welding;
    • guaiacum;
    • yew;
    • hop hornbeam;
    • caesalpinia;
    • casuarina;
    • boxwood;
    • iron ixora.

    Wood features

    A characteristic feature of iron trees is the unusual structure of the trunk. And among these features include the following:

    1. The composition of the bark includes special tannins that prevent the development of fungal diseases and protect against pests.
    2. The barrel is made of fibers that are resistant to corrosion and acids.
    3. The tree actively grows up to 200 years. At the same time, its growth may continue further.
    4. The wood has a high density (1 t/m 3 ), with a moisture content of 12 percent. This is what slows down the aging process.
    5. Trunk girth can be more than 2 meters.

    These unusual qualities allow iron trees to survive in various parts of the world in both heat and cold. Neither high humidity nor a dry climate can harm such a plant.


    As mentioned above, the group "iron trees" includes various species, each of which has found its own application. Such plants can be used in various fields, for example: