Many gardeners dream of having a small backyard orchard with healthy fruit trees producing a good harvest year after year. If you have clay soil, however, that dream may seem unlikely to become a reality since fruit trees favor lighter, drier soils than clay.
If you have clay soil, you can still grow fruit trees! It will not be as simple as digging a hole and planting the tree, but with the right tree cultivar and some soil and site preparation, you can nurture a healthy backyard orchard.
How Do You Know If You Have Clay Soil?
You can’t always tell just by looking at what type of soil you have, which is why it is important to conduct a soil test before you do anything else. Your local Extension agency can give you instructions for gathering your soil sample and sending it in for analysis.
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Your soil test will tell you what type of soil you have, which is a great starting point. Even within the category of clay soil, there are varieties–sandy clay, clay loam, heavy clay, etc. Knowing what you have will help you choose the right tree.
Soil tests provide a great deal of other valuable information, as well, such as your soil’s pH level (acidic or alkaline), nutrient contents, and whether any harmful organisms are present. Even after you plant your tree, it is a good idea to test your soil every two to three years so that you can make adjustments if you need to.
If your soil test shows that you have sandy clay or clay loam, you are in luck! Several fruit trees can grow well in sandy clay or clay loam. If your test shows that you have heavy clay, it is not time to give up; with some site or soil modifications, you will also be able to grow some healthy fruit trees (source).
Will Apple Trees Grow in Clay Soil?
Apple trees can thrive if your soil is clay loam. The soil must drain well, and the pH level should be between 5.5 and 7.5.
Most apple trees are not self-fruitful. That means that in order to produce a harvest, you will need more than one apple tree; this will allow the trees to cross-pollinate.
This also means that if you want to grow apples, you will need two planting sites. Standard-sized trees should be planted 25 to 40 feet apart, semi-dwarf trees should be spaced 12 to 20 feet apart, and dwarf trees should be planted six to ten feet apart (source).
Many apple tree rootstocks are susceptible to root rot and other diseases that occur when the soil is too wet. For that reason, if you have heavy clay soil, you will need to modify your planting sites. See below for suggestions.
Poland 18 (P.18) is one of the only apple tree rootstocks that do well in heavy, wet soils. P.18 produces trees that are 18 to 25 feet tall, which is approximately the height other standard-sized apple trees reach maturity.
In addition to its moisture tolerance, P.18 offers other advantages as well. It is resistant to collar rot, which is a common problem for apple trees, and it is tolerant of fire blight (source).
Will Cherry and Other Stone Fruit Trees Grow in Clay Soil?
Unfortunately, sweet cherry trees are not tolerant of clay soils. If you hope to grow sweet cherries, you will need to consider some alternate growing sites or a different kind of fruit.
Tart cherry trees, on the other hand, will tolerate clay or other heavy soils if you use the Mazzard rootstock. Mazzard’s root system is quite fibrous, which allows it to be more adaptable to heavy soils than other common rootstocks. Furthermore, Mazzard is extremely popular among North American growers, which means it will be easy to find (source).
Other stone fruits, like peaches, nectarines, and apricots, are highly susceptible to soil-borne diseases and organisms that are exacerbated by wet, heavy soils. This makes them poor candidates for clay soils. See below for suggestions regarding rootstocks and understand that you may still need to modify your planting site to make stone fruit growing possible.
In addition to the Mazzard rootstock for tart cherry trees, there are some rootstocks for peach trees that are tolerant of heavy soils like clay. Krymsk® 86, Viking, Rootpac® R, and Lovell have all shown tolerance for high soil moisture.
However, it is important to note that these rootstocks are not equally tolerant of harmful soil-borne organisms. Consult a local expert about these rootstocks and use the results of your soil test to guide you to the right selection (source).
Will Citrus and Avocado Trees Grow in Clay Soil?
Citrus and avocado trees are not well-adapted to clay soils because both species require excellent drainage.
With some modifications to your soil to ensure proper drainage, you may be able to cultivate a citrus tree. However, unless you live in a subtropical climate, you will be better off planting your citrus tree in a container.
Likewise, if you have the right climate, you may still be able to successfully cultivate an avocado tree if you modify your soil. Avocados are highly sensitive to temperature, so if you do not live in a subtropical zone, it may be best to try growing a different tree altogether.
If you live in the right climate for citrus trees, try using the Sour Orange or Trifoliate Orange rootstocks. Both Sour Orange and Trifoliate Orange are tried-and-true rootstocks that have shown tolerance of wet, clay soils (source).
Most of the rootstock research done on avocado trees has been to measure their tolerance of salt since they are often planted in coastal regions. For that reason, research on avocado rootstocks’ tolerance of wet soils is not readily available. If your climate is right for avocados, consult a local expert to guide you to the right selection, or see below for ways to modify your soil.
How To Work With Clay Soil
You may be tempted to give up before you even start–clay soil is certainly not the easiest soil to work with when planting fruit trees is the goal. However, there are three solutions that are well worth the time and effort:
- Planting your trees in raised beds.
- Growing dwarf fruit trees in containers.
- Using compost to change the structure and condition of your soil over time.
Planting in Raised Beds
Constructing a raised bed for your fruit tree is a highly recommended solution for fruit growers whose soil is less than ideal. There are multiple types of raised beds, but the best type for fruit trees is the supported raised bed.
Supported raised beds are framed right on the ground’s surface. The frame of wood, stone, masonry or other material rises about 12 inches high and encloses a rectangular area filled to the top with soil.
In addition to buying the materials for your raised bed’s frame, you will need to buy several cubic feet of soil to fill the frame. This may seem like a hassle, but it is actually one of the best benefits of planting in a raised bed: purchasing your soil gives you control over its composition and quality. You will be able to buy soil that is disease-free, has good drainage, and has an ideal pH level for the fruit tree you want to plant.
Your tree’s roots will still encounter the clay underneath your raised bed. However, fruit tree’s roots are most prolific in the top 12 to 18 inches of the soil; they can only grow where they find enough oxygen. The root system will extend much farther horizontally than it will vertically (See How Deep Do Fruit Tree Roots Grow?).
With that in mind, your raised bed should be wide enough for adequate root development while your tree is still getting established, but you do not need to worry about building your bed to be deeper than one foot.
If you would like to learn more, check out our article, Growing Fruit Trees in Raised Beds: Everything You Need to Know.
Growing Dwarf Trees in Containers
Not all gardeners have adequate space or a large enough budget to build a raised bed. Fortunately, containers offer similar benefits on a smaller scale.
Apples, peaches, plums, cherries, citrus, avocados, and a wide range of other fruit trees can grow and produce fruit if they are planted in a pot rather than in the ground. The key is to make sure that you have a container-friendly dwarf variety–standard-sized trees will outgrow their containers quickly!
Like raised beds, containers allow you to control the quality of the soil or potting mix that you use. Instead of gambling on your native soil, you can ensure that your tree will have soil that is well-drained, disease-free, and nutrient-rich.
Even better, is the fact that you can take your local climate out of the equation when you plant a fruit tree in a container. As long as your pot is relatively mobile, you can move your tree to shelter for the winter. This makes it possible for growers who have harsh winters to grow subtropical fruits like key lime, Meyer lemon, and avocados.
Two of the most important considerations to take into account are container size and mobility.
- Size. Do some research on the dwarf tree you want to plant and learn how much space its root system will need. Use that information to find a pot that is large enough.
- Mobility. When your pot is full of soil and a tree, it will be extremely heavy. Adding casters to the bottom of your container can help. If that is not an option, buy a caddy to hold your container and allow you to move it more easily.
For more information, read our article “Growing Cherry Trees in Pots: Keys to Success.” While the article focuses on cherries, many of the principles will apply to other stone fruits as well.
Our article “Can You Grow Lemon Trees in Zone 6?” contains valuable information about growing lemon trees in containers. Many of the concepts in the article are relevant to growing limes and other citrus, too.
Using Compost to Improve Soil Structure
If you want to improve the structure and quality of your soil over the long run, compost is the best option.
It is necessary to note, however, using compost as a soil amendment, while highly effective, is a lengthy process. It will be worth it in the end, but adding compost to your soil today will not prepare your soil to host a fruit tree next year.
Compost is made up of rich, organic matter, so when you mix it with your native soil, you create a better habitat for earthworms and other beneficial soil-borne organisms. These populations contribute further to the health of your soil.
Adding a generous amount of compost to your soil annually perpetuates the populations of helpful organisms and changes the chemical and physical make-up of your soil as well. Even heavy clay soils will have improved drainage and airflow over time.
To use compost as a soil amendment, start by spreading a two-inch layer of mature compost on the surface of your soil. Use a tiller to mix the compost well into the top eight inches of the soil. Once you have finished mixing, your soil is ready for planting or smoothing over (source).
If you repeat that process every year, your clay soil will become better suited to fruit trees and many other species that would otherwise struggle in clay.
For more information on how you can start composting, take a look at our article “Compost Tumblers vs. Worm Bins,” which is a helpful guide for setting up a composting system that will work for you.
Non-Fruiting Trees That Grow Well In Clay
If it seems too daunting to amend your planting site to suit a fruit tree, consider planting a non-fruiting tree. Because they do not have the same drainage and nutrient needs as fruit trees, there are a wider range of species available that are adaptable to clay soils.
The following tree species grow well in clay and other poorly drained soils:
- Swamp White Oak (Quercus bicolor)
- Honeylocust (Gleditsia triacanthos)
- Crabapple (Malus cultivars)
- Willow (Salix species)
- Poplar and cottonwood (Populus species)
Consult a local nursery or arborist to learn which species are available in your area.
While clay soil, especially heavy clay, can be difficult to work with, it doesn’t have to put an end to your hopes of harvesting fruit from your own tree. Raised beds and containers make a variety of fruit trees available to you, and compost can make your native soil much easier to work with. With the right rootstock in the right location, you can look forward to a delicious harvest.