Master Gardener, Fred Hoffman gives tips for growing Citrus in Containers. Citrus loves the California sun—a prime ingredient for growth. Get the 4-1-1 on growing citrus and grow a tree in your very own backyard—even if you don’t have the space!
The first family of citrus growers in Northern California are the Dillons, who began experimenting with dwarf varieties of orange, lemon and lime trees for home orchards back in the 1940's. Over the decades, founder Floyd Dillon, son Don Dillon, grandson Don Jr. and granddaughter Mary Helen Seeger have presided over Four Winds Growers, a wholesale citrus tree provider, with growing grounds based in Winters and Fremont.
Their website, fourwindsgrowers.com, offers up many solutions to home citrus growing problems in our area, along with information about the wide variety of citrus trees available that do well here. And a talk with Mary Helen and her husband, Cedar, offer even more insights for the successful backyard citrus grower.
Looking for year round oranges? Cedar Seeger suggests four varieties of trees that can keep you in orange juice nearly 10 months a year. "The Washington Navel, Lane Late Navel, Trovita and Midknight Seedless Valencia all feature sweet and juicy fruit that are nearly seedless," says Cedar. "The Washington ripens in winter and early spring; that's followed by the Trovita in the spring; Midknight in the early summer; then, the Lane Late, throughout the summer."
Add to that an Owari Satsuma mandarin that ripens in November and December, and you can be picking fresh, tasty citrus nearly all year.
Where should you plant citrus? A sunny, wind-free, southern exposure is best. Mary Helen Seeger puts it more succinctly, "As my father likes to say, 'Plant citrus wherever the cat sleeps.'"
Citrus grown in large containers on a sunny patio can be quite successful. "Either repot or change the soil in the containers every two or three years," advises Cedar. "You don't have to necessarily go to a larger pot if the roots aren't bound. This process helps provide fresh nutrients and controls circling roots."
Regular food and water are basic necessities for citrus. "A complete fertilizer with micronutrients, such as a food labeled for citrus, is a good choice," says Mary Helen. Chimes in Cedar: "Since citrus roots tend to be in the top two feet of the soil, they prefer to be flooded. That is why it is best to keep them out of lawn areas that requires shallow frequent watering. If drainage is a problem, then planting citrus in raised beds or containers is a good option."
And to stave off winter frost? "Buy the large, outdoor Christmas light bulbs and string them through the tree," says Cedar. "Turn them on when a frost is expected. And be sure to thoroughly soak the soil around any containerized citrus the night before. Frost in dry soils can draw the remaining moisture away from the plant roots, further stressing the plant."
It's a California scenario almost as old as the state itself: a leisurely weekend breakfast on the backyard patio, featuring fresh squeezed orange juice, using fruit plucked from a tree within arm's reach—in February. That fresh-squeezed flavor shouldn't just be a seasonal treat here. There's no reason why you can't enjoy fresh oranges most of the year.
"With just two orange trees, valley gardeners can have oranges from November to September," says Lance Walheim, author of the book "Citrus: The Complete Guide To Selecting and Growing More than 100 Varieties" (Ironwood Press). "All you need is a Washington Navel Orange and a Valencia Orange," he says.
Both the Washington Navel and the Valencia are tried and true performers here in the San Joaquin and Sacramento Valleys, well-known for producing flavorful fruit. The Washington Navel is productive here from mid-November to April; Valencias bear fruit March to September. Walheim advises that for the best crop, fertilize your oranges and other citrus trees now. "All citrus need nitrogen this time of year, either sulfate of ammonia or a packaged citrus food, which contains micronutrients in addition to the nitrogen," he explains.
Orange trees, as well as other citrus varieties, are available from late winter through the spring at area nurseries. Walheim advises choosing citrus in smaller containers, such as those sold in three and five gallon cans, bypassing those packed in seven gallon and bigger pots. "Smaller sizes are less likely to be rootbound and often become established more quickly than plants set out from larger containers," he explains.
Advice from Four Winds Growers (www.fourwindgrowers.com)
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:
- Select the right size pot with adequate drainage holes.
- 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.
- Develop a watering schedule so the tree stays on the dry side of moist.
- Provide 8 or more hours of direct sunlight or grow light per day.
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.
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.
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.
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.
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 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.
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.
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.
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.
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.
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.
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.