How to Grow a Hawthorn Tree

A hawthorn tree in full bloom

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The genus Crataegus gifts us with some of the most pleasing ornamental small trees and shrubs that gardeners and landscape designers can put into a landscape. It is the perfect size for smaller settings as a single specimen and packs an eye-pleasing punch when grouped en masse in larger gardens.

Often the species of the genus find themself susceptible to issues such as disease or insects. While integrated pest management does help, the genus' issues have really been addressed through selective cultivation and grafting. Today in ornamental horticulture, the most popular hawthorns are grafted or cultivars.

Besides disease and insects, an issue that has been bred out of some hawthorn selections is their intimidating thorns that can grow up to three inches long on some species. The work of those in the nursery trade to develop resistant varieties has allowed the public to enjoy this beautiful genus to its fullest.

Common Name  Hawthorn
Botanical Name Crataegus spp.
Family Name Rosaceae
 Plant Type  Flowering tree, large shrub
 Mature Size  15 to 50 ft tall, 5-20 ft. wide
 Sun Exposure  Full sun
 Soil Type  Moist, well-drained
 Soil pH  Slightly acidic
 Bloom Time  May, early June
 Flower Color  White, pink
 Hardiness Zones  Varies by species
 Native Area Europe, Asia, North Africa, North America

Hawthorn Care

There are three elements to being successful when growing a hawthorn. You will need to accept that they are susceptible to some issues and realize that you will have to take some steps to deal with those issues.

Normally it is a great idea to go native, and it still is, but in doing so, you will need to be extra vigilant in your integrated pest management program. This is a great example of a tree where it is worth bringing in a certified arborist to do some yearly tree care.

Plan to do some research and find out what insects and diseases are in your area and if they will affect the species or variety you have chosen. You can find this information from the Plant Sentinel Network or your local extension service.

Finally, if you've chosen a variety that still has its thorns, plan to place it someplace that is safely out of the way from pathways and playing children. The thorns (strong enough to pierce the skull) can cause dangerous piercing wounds and severe infections with lingering conditions.

Light

This flowering genus will do best in a location that receives full sun. Placing the tree in a location with anything less will produce a noticeable drop in blossoms.

Soil

Shockingly with as susceptible as the genus is, it will tolerate any soil type and pH level as long as the soil is well-draining. The soil condition will not have any obvious effect on the plant's health or bloom production. Its ideal soil is slightly moist, slightly acidic, and well-draining, but the soil is not the biggest priority when dealing with hawthorns.

Water

Establishing your hawthorn will require you to provide it with plenty of moisture for the first two years or so. To do this, it's best to water it weekly. Figure out just how much to water your tree by measuring its diameter at your knee height with a set of calipers. Then give it 10 gallons per inch every week for the next two seasons, re-measuring every so often.

To ensure you get profuse blooms, you will want to keep your tree's soil moist but not soaked. If this requires supplemental watering, then you may need to water as needed. Adding a layer of mulch around the tree's base at a depth of two inches out to the dripline without touching the trunk will help it retain moisture.

Temperature and Humidity

The hardiness will vary on the species or cultivar and may differ greatly as the genus is dispersed over many continents. Research the viability of a certain species or cultivar in your hardiness zone before deciding to plant!

Fertilizer

Giving hawthorns an application of fertilizer in the fall should be on your to-do list every year. Being a flowering tree, it will benefit from the added boost of nutrients you provide it. Apply a granular slow-release fertilizer formulated for flowering trees and shrubs, and your hawthorn will be bursting with blooms.

Types of Hawthorn Tree

If you go the non-native route, pick a disease- and pest-resistant variety of hawthorn. There are many selections of Cratageus available that are resistant to fire blight and rust which are equally beautiful. You will need to find the right tree for your zone; the choices are endless. Here are a few popular choices in the nursery trade:

Canadian, C. canadensis - A frost-hardy Hawthorn that grows to about 30 feet. It can withstand city pollution and is grows

Washington Hawthorn, C. phaenopyrum - A small hawthorn with extremely bright berries and striking fall color.

Cockspur Hawthorn, C. crus-galli - Low growing, wide branched thicket like hawthorn with branches that touch the ground. It Produces an assortment of colors in the fall.

Copenhagen Hawthorn, C. intricata - A small shrub-like hawthorn, hence the specific name, that grows only to about 10 feet. It is known for its value as a habitat for wildlife and as a food source for pollinators.

Pruning

First, pruning a hawthorn is a job that needs to be done carefully and properly protected with leather gloves, eye protection, and a helmet. The thorns on a hawthorn are 1 1/2 to 3 inches long and as hard as nails, meaning they can pierce flesh and with enough force bone without much issue. The thorns also carry bacteria that can be worse than the puncture wounds themselves.

Hawthorn trees may develop thicket-like habits if they are not trained to have a single leader and outward branches. To train your tree, you will want to establish a single leader and cut off any low-hanging branches that create a sharp V-shaped crotch or X-shaped intersection with another branch. This should be done annually in the fall after the tree has dropped its leaves. You should continue training your hawthorn in this way until it is shaped into the desired form. When it is too large to prune from the ground, it's best to call a licensed arborist as this can be a dangerous tree to prune.

Common Pests and Plant Diseases

Hawthorns most often suffer from hawthorn rust and fire blight. Hawthorn rust is a tree disease caused by the fungus Gymnosporangium globosum. This disease rarely kills trees but will always disfigure them, and worst of all, if a tree is infected, it can either only be managed or taken down and not cured. This is why it is important to consider choosing rust-resistant hawthorns. Rust is caused by excessive moisture on trees and in the soil around trees. To alleviate this issue, avoid excessive watering and prune your tree to allow good airflow.

Fire blight is a bacterial disease that affects hawthorns. The disease kills blossoms, shoots, and causes the dieback of branches. In severe cases, it can cause the trees to die. To control blight, prune your hawthorn to remove infected branches before the disease kills the tree. You can prevent blight by planting resistant varieties.