Growing Fruit Crops in Containers

Growing Fruit Crops in Containers

Julian W. Sauls and Larry K Jackson

Florida Cooperative Extension Service
Institute of Food and AgriculturalSciences
University of Florida
Fruit Crops Fact Sheet FC-57
Used with permission

People frequently want to grow some type of fruit tree in a container, usually because of poor soil, improper climate or lack of sufficient space as is often the case around apartments and condominiums. Fortunately, a wide variety of fruit trees can be grown in containers with some degree of success. However, such plants will rarely be as attractive or grow and fruit as well as those grown under optimal conditions in the ground.

One of the principal reasons for growing fruit trees in containers is portability. Thus, tropical and subtropical fruits can be grown in containers in areas where freezes might occur. The size and mobility of the containers allows the plants to be moved indoors during periods of predicated freezing temperatures. Many fruits which can be successfully grown in containers are listed in Table 1. Most will produce some fruit if given proper care. The list is by no means complete, as most fruit trees could be grown in containers if the size of the container were not a problem. [The wider availability of many types of dwarf fruit trees also greatly increases the choices that container gardeners have.]

Containers may be plastic, metal, clay, ceramic, wood or any others normally available at nurseries and garden supply stores. Used whisky barrels cut in half are excellent or wooden boxes may be built to order. The container should have adequate holes at the bottom for drainage of excess water.

Potting

The drainage holes of the container may be covered with pieces of screen mesh to prevent the soil from washing out. A layer of gravel 1-2 in. (2-5 cm) should be placed in the bottom of the container to facilitate drainage.

Any commercial potting soil should be suitable for growing fruit trees. However, a mixture of 1 part sand, 1 part peat and 1 part bark, perlite or vermiculite will also serve quite well. The potting medium should be loose enough to permit adequate but not excessive drainage.

Examine the root system of the plant. If it is pot-bound or has experienced severe root crowding in its previous container, judiciously prune some of the larger roots and loosen others to facilitate root proliferation in the new container.

The container should be partially filled with soil (large containers should be filled at the site they are expected to remain). Place the plant in the partially filled container of soil to its correct planting depth which is the depth at which the plant was previously grown. The final soil surface should be 1-4 in. (2-10 cm) below the rim of the container, in direct proportion to container size, to allow for watering.

Complete filling the container and firm the soil around the plant. Water thoroughly but do not fertilize until new growth commences. An attractive mulch of bark, gravel or other material can be added to improve the appearance of the container.

Light

Most fruit crops grow best in full sunlight, but some will do well in partial shade. However, plants grow in direct proportion to the amount of light received, if other conditions are optimum, so container grown fruit trees should be placed where they will receive maximum sunlight.

It is important that rapid changes in light exposure be avoided, i.e. plants growing in partial shade should not be suddenly exposed to complete, direct sunlight. Any plants that are to be grown indoors part of the year should be acclimated by gradually reducing the light to which they are exposed for 2-23 weeks before moving them inside and vice versa for plants being moved outdoors. Such acclimation is not necessary for plants that are to be moved indoors for few days during freezes.

Temperature

Tropical and subtropical fruit trees cannot tolerate freezing temperatures for very long. Some will be killed back to the soil by mild freezes while only small twigs will be killed on others. Some root damage can occur because the root system is not as well insulated from cold in a container as it would be in the ground.

Cold hardiness depends on the plant, the care it receives and many other factors. Protection from severe cold is essential for all tropical and subtropical fruits growing in containers. Plants may be covered temporarily with blankets, paper or other material as protection against hard freezes, but such material should be removed each morning to allow the plants to take full advantage of incoming solar radiation. Plants moved indoors during cold spells should be placed away from drafts caused by doors and heating ducts.

Water

Most container grown plants that do not thrive are usually in poor condition due to faulty watering practices, usually overwatering. Plants growing in containers should be watered only as needed. The frequency of watering depends upon such variables as type and size of plant, type and size of container, temperature, humidity, potting medium and other factors. For most plants, the upper surface of the soil should be allowed to become dry to the touch before watering. Then water thoroughly by slowly filling the container. Good drainage of excess water from the container is essential.

The soil in plastic, metal and ceramic containers generally stays wet longer than it does in wood or clay containers, which allow water to evaporate through the sides. Cool weather generally slows plant growth and this reduces the plant's need for moisture, so watering should be less frequent during cool weather.

Fertilizer

Good nutrition is essential to the success of container-grown fruit trees, but excess fertilizer can result in overgrowth, poor fruit and possible dieback due to salt accumulation. Water-soluble fertilizers are widely available and should be used according to label directions. If mature foliage is deep green in color, adequate fertilizer is being used.

Many fertilizers can be used successfully, provided they are complete and balanced. The fertilizer should contain nitrogen, phosphorus and potassium in balanced proportions and should include lesser amounts or traces of magnesium, iron, manganese, zinc and copper. The ingredients and quantities of each nutrient contained are listed on the fertilizer label.

Salt accumulation may sometimes be a problem and is often indicated by a white crust on the soil or container and may be due to excess fertilization and/or water containing considerable soluble salts. Should this occur, the container should be thoroughly leached by slowly running water through the container for several minutes. This will carry excess salts down through the soil and out the drainage holes.

Pruning

With few exceptions, fruit trees will develop and maintain their natural shape with little or no training or pruning. They will occasionally become "leggy" when grown indoors or in poor light for too long. Leggy branches should be partially cut back to force branching and bushiness.

Frequently, the top will grow rather large and begin to exceed the capability of the root system. Consequently, some leaf shed and twig dieback will often occur. Such plants should be pruned back heavily to rejuvenate them. When plants area heavily pruned, less fertilizer and water will be necessary to compensate for the reduced plant size.

Fruitfulness

Most fruit crops will produce fruit in containers, given time, good care and adequate size and age. However, naturally large fruit trees will require larger containers to bear much fruit, as the amount of fruit produced is proportional to the plant's size, so large yields should not be expected. Many fruit plants need to be large in order to fruit at all, so their size can quickly become limiting in containers. Many fruit crops also require the presence of pollenizer cultivars and pollinating insects. Flowers can be pollinated by hand.

It must be emphasized that even under the best of conditions, fruit production in containers will not equal the quantity produced on trees in the ground, as fruit trees grown in containers are usually growing under sup-optimal conditions.

Tropical fruits
Avocado / Jaboticaba
Banana / Kei apple
Capulin cherry / Miracle fruit
Cattley guava / Natal plum
Ceylon gooseberry / Papaya
Coffee / Pineapple
Guava / Pitanga
Grumichama / Pitomba
Imbe
/ Citrus fruits
Calamondin
Grapefruit (dwarf)
Key lime
Kumquat
Lemon
Lime
Limequat
Orange (dwarf)
/ Temperate fruits
Apple (dwarf)
Blackberry
Blueberry
Fig
Stonefruit (dwarf)

Table l. Some fruit crops which can be successfully grown in containers.
Tree size will normally be limited by the size of the container.

California Rare Fruit Growers, Inc.
Questions or comments? Contact us.

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Garden Hints

How to grow a potted tree on your patio or porch

SALEM - You don't need a large piece of property to grow a tree. If you have a porch, patio or balcony, you might want try growing a tree in large container pots.
Neil Bell, an Oregon State University community horticulturist, and Gail Gredler, horticulturist and education director for the Oregon Garden in Silverton, suggest some guidelines to help you choose and grow a healthy container tree.
Pay attention to the expected size of a mature tree. For obvious reasons, a tree whose mature size is on the small side will be most appropriate for container growing. The size of a tree is usually proportional to the size of the root system, and containers will necessarily restrict root growth.
Smaller species and dwarf varieties of standard species are good candidates for containers. Evergreens like Mugo pine (Pinus mugo), Korean fir (Abies koreana), cryptomeria (Cryptomeria japonica), Skyrocket juniper (Juniperis scopulorum 'Skyrocket'), boxwood (Buxus spp.), English yew (Taxus baccata), strawberry madrone (Arbutus unedo), dwarf camellias, and just about any dwarf conifer can be grown in containers. Deciduous trees like Japanese maple (Acer palmatum), star magnolia (Magnolia stellata), cutleaf vine maple (Acer circinatum 'Monroe'), dwarf weeping birch (Betula pendula 'Trost's Dwarf'), lacebark elm (Ulmus parvifolia 'Frosty', 'Seiju' or 'Yatsabusa' and crepe myrtle (Lagerstroemia indica) also do well in containers.
For those with sunny indoor space, citrus trees (Meyer lemon, Baerr's lime, mandarin orange) or other tender evergreen trees can be grown in containers outside in the summer and inside during the colder months.
Growing anything in a container starts with selecting a pot and soil. Clay pots are heavier than plastic, but are more stable in windy conditions, especially with larger trees.
Careful soil selection is very critical to the health of your tree. Do not use soil directly from your garden. Instead, use a soil-based compost, with good organic matter content and preferably some perlite or pumice to make the mix porous, which keeps air in the soil. These are commercially available in bags at nurseries and in garden sections of discount stores.
"Good container soils retain water without becoming waterlogged," said Bell. "They also provide part of the nutrient requirements of the plants and do not get compacted."
Caring for a containerized tree is more work than growing a tree in the ground. The roots of a containerized tree can only search for water and nutrients within the confines of the pot, so you will need to provide adequate amounts of both.
Trees in containers, especially porous containers, will need regular watering and feeding. Fertilize with a balanced, slow-release fertilizer.
Protect the tree roots from winter cold by keeping the container in a protected spot or a cool greenhouse or wrap the pot with an insulating material during the coldest months. Pots should be about as wide as they are high to provide the best insulation to the roots.
If a tree starts to outgrow its container, you have several choices. Plant it in the ground, plant it in a larger container, or prune the roots back by one third and plant it back in its current container. Root pruning is a similar technique to bonsai and will help to keep the tree small.
Trees in containers can add a lot of ambience to your patio or deck. With a little extra effort, you can enjoy a containerized tree for many years.
By: Carol Savonen
Source: Neil Bell, Gail Gredler
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News & Garden Archives

Growing Citrus in Containers

Dwarf citrus are especially suited for container growing as they can be kept at manageable sizes. Container growing allows gardeners to overcome poor soil conditions or limited space in a landscape. People enjoy their trees in decorative pots on their patio or apartment balcony. Many customers have cold winters and bring their citrus indoors during freezing weather. For some pictures of successful container plantings take a moment to view this slide show.
The keys to successful container growing are:

1. Select the right size pot with adequate drainage holes.
2. Use a soil mix that is lightweight and drains well. If the mix is dense or contains peat moss, amend your soil mix with 1/4-1/3 volume of 1" redwood shavings.
3. Develop a watering schedule so the tree stays on the dry side of moist.
4. Provide 8 or more hours of direct sunlight or grow light per day.
5. Plant the tree so the root collar is above the soil line and the top of the root crown is barely below the soil. Do not cover the trunk with soil at all.

On this page:
Selecting Planting Containers | How to Plant in Containers
Selecting a Location | Watering | Fertilizer | Suckering
Thorns | Pruning | Pollination | Espaliering
Beneficial Insects | Pest Insects | Frost
Selecting Planting Containers
We recommend a 6-9" container for our one year trees and a 10-14" container for our 2-3 year trees. A variety of decorative plastic containers are available at reasonable prices. Clay pots and wooden containers are very attractive but less mobile choices. When selecting a container, be sure there are sufficient drainage holes. Drilling extra holes is an easy way to improve drainage with wood or plastic. As the tree grows, increase the container size to a 16-20" diameter pot. Do not start with a pot that is too large as it makes soil moisture levels harder to control with small trees. Be sure your container drains freely, raising it off the ground if need be.
How to Plant in Containers
We recommend using commercially available potting mixes. Some experts make their own mixes using wood shavings, sand, and compost. Using dirt in a container is not advisable. Rose formulations can work, but the perfect high air filled porosity mix can be hard to find. If you can not find a mix without sphagnum peat moss, amend the soil mix with a 1/4- 1/3 volume of 1" redwood shavings. Our 2-3 year trees are shipped with shavings suitable for potting mix amendments. Cedar shavings can be used as well, but avoid pine and spruce. Once your soil mix is prepared, the container is selected and the tree's eventual location is known you are ready to begin potting.
Place one inch of soil in the bottom of your new container. Gently remove the roots and soil from the old container. Try to keep the root ball intact. Place the root ball in the new container and fill with your fresh potting mix. The top of the roots should be just barely beneath the top of the soil level. Loosely tie tree to a stake if needed. Press the soil around the root ball to provide stability and water deeply. Loosely tie tree to a stake. Repotting with fresh soil mix every year or two will provide fresh nutrients to the soil.
Selecting a Location for Outdoor Containers
Sunny, wind free locations with southern exposure are the best. If in doubt, leave the tree in its plastic container and place it in the spot you have in mind. After a week or two, you should be able to tell whether or not it is thriving. Reflected heat from sidewalks or houses can also help to create a warmer microclimate. Avoid lawns that get frequent, shallow watering.
Watering
Consistency is the key with citrus watering. Citrus trees require soil that is moist but never soggy. Watering frequency will vary with soil porosity, tree size, and environmental factors. DO NOT WATER IF THE TOP OF THE SOIL IS DRY WITHOUT CHECKING THE SOIL AT ROOT LEVEL! A simple moisture meter, available at garden supply stores, will read moisture at the root level. This inexpensive tool will allow you to never have to guess about whether or not a plant needs water.
A wilted tree that perks up within 24 hours after watering indicates the roots got too dry. Adjust watering schedule accordingly. A tree with yellow or cupped leaves, or leaves that don't look perky AFTER watering can indicate excessive watering and soggy roots. Give your tree water less often.
Citrus prefer infrequent, deep watering to frequent, shallow sprinklings. Creating a watering basin around the tree's drip line can aid in deep watering. Deeper watering promotes deeper root growth and strengthens your tree. Generally, once or twice a week deep watering works well for container specimens. Be sure to adjust based on weather conditions!
In general, it is probably best to water in the morning, but if plants are dry or wilted it is better to water them right away than wait until morning. See our watering page for more.
Fertilizer
Citrus trees feed heavily on nitrogen. Your fertilizer should have more nitrogen (N) than phosphorous (P) or potassium (K). Use at least a 2-1-1 ratio. Miracid Soil Acidifier is a water-soluble product that works well and is a 3-1-1 ratio. In some regions, you may be able to find specialized citrus/avocado fertilizers. Buy a good brand and apply according to package directions.
Also important are trace minerals like iron, zinc, and manganese, so make sure those are included as well. Many all-purpose products will work. We prefer slow release fertilizers in the granular form rather than fertilizer stakes. Follow rates on the package carefully as fertilizers come in different strengths, release rates, and application schedules. We recommend that you fertilize more often than recommended with most slow release fertilizers. Foliar applications of trace minerals in the form of kelp or other soluble fertilizers can be effective on leaves when half their mature size. Yellowing leaves indicate lack of fertilizer or poor drainage.
Suckering
Know where the graft union in on your tree. It can usually be seen as a diagonal scar between 4 and 8 inches from the soil. Remove all shoot growth below the graft. These so-called "suckers" take vitality from the top of the tree (the fruiting wood). Especially on young trees, they are very vigorous. Remove suckers as soon as they are observed. See photos.
Thorns
Thorns are removed from rootstocks when they are grafted. Juvenile fruiting wood will sometimes have thorns; this is a young plant's way of defending against grazing animals. As the tree matures, thorns will not appear as often. Prune off thorns if desired. Check thorny branches to see if they are fruiting wood or rootstock.
Pruning
Citrus may be pruned to any desired shape. Pruning is fine any time of year, except in the winter for outdoor trees. Pinching back tips of new growth is the best way to round out the trees without impacting future fruit. Citrus will look fuller with occasional pruning to shape leggy branches. Some trees may develop erratic juvenile growth above the graft. If so, prune for shape and balance. Any growth above the graft can eventually bear fruit. Do not be afraid to cut off branches. It will stimulate growth and multiple branches from the site you pruned. Well-pruned trees have higher fruit yields and are less prone to branch breakage.
Pollination
Most citrus are self-pollinating, even indoors. Some people enjoy pollinating their trees and can do so by using a small soft brush or cotton swab to transfer pollen among the flowers.
Espaliering
Four Winds citrus can be trained to grow on trellises. Simply use green garden ties to hold branches in place and prune to encourage desired branching patterns.
Beneficial Insects
Most insects do no harm to citrus trees! Spiders, lady beetles, lacewings, and preying mantids (praying mantis) are some of the beneficial insects you may see around citrus trees outdoors. You can even buy some of these predator insects in local nurseries for release in your garden.
Pest Insects
Keep your tree free of ants. They will farm scales or aphids, moving them from place to place, milking their secretions, and protecting them from beneficial insects. Ant baits may be helpful.
If you find harmful insects like scales, aphids, or mites, a household spray bottle of water with some mild dish soap could be all you need. If insects persist, the usual nursery treatment is a 1% solution of light horticultural oil. Learn more.
Frost
Even temperate locations can drop below freezing, so it's good to have a plan in mind for that eventuality. Christmas lights strung around your tree will provide some protection, as will an antitranspirant like Cloud Cover. A frost blanket, loosely draped over and around the tree, will also help. Or, you can overwinter your tree indoors.
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