Citrus trees 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 a patio or apartment balcony. Many growers have cold winters and bring their citrus indoors during freezing weather. These tips can help you on the way to successful citrus growing in containers.
Selecting Planting Containers
We recommend a 10-12" container for our entry trees and a 12-14" container for our premium trees. A variety of decorative plastic containers are available at reasonable prices. Clay pots and wooden containers are 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 (the next pot size up). Do not start with a pot that is too large as it makes soil moisture levels harder to control with small trees.
Selecting a Location for Outdoor Containers
Provide 8 or more hours of direct sunlight per day. If less than 6 hours of natural full sun is provided, supplement with grow lights. Usually, an unobstructed South or Southwest facing window is ideal. 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 placing containerized citrus trees on or near lawns that get frequent, shallow watering. To reduce excessive heat on the roots, try nesting plain plastic nursery pots into slightly larger decorative pots. This can help roots stay cooler. Be sure the pot never sits in standing drainage water. A saucer with river rock placed beneath the container is one of the best ways to ensure adequate drainage. Protecting young trees and tender new growth from the scalding sun is an important step to take for growers in warmer climates or with particularly hot yards. Plant Guard tree paint and foliar spray is a great organic product and is highly recommended for those who want an easy-to-apply layer of protection.
Growing Container Citrus Indoors
If your winters regularly drop well below 32°F then this is the method for you. This is such a fantastic option for growers in colder regions that only dreamed of owning their own citrus tree. With the right tips, tricks, and tools, growers all over the US have blown us away with what they have been able to accomplish. Here is a great PDF Guide and Indoor Citrus Growing Blog to walk you through the steps and get you harvesting delicious citrus fruit from inside your home. Maybe you already have an indoor citrus tree and want to share it with the outside world? We have a guide for that too. Learn how to transition your citrus tree outdoors here.
Selecting a Soil Mix for Container Planting
We recommend using a commercially available citrus potting mix like our Primo Potting Mix or making our 5-1-1 mix. This mix consists of 5 parts fine bark(aim for 1/2" pieces), 1 part perlite, and one part potting soil. This mix will break down very slowly, allow for adequate drainage, promote healthy root growth. Using dirt (native soil from your yard) in a container is not advisable. We also advise against putting gravel or any other material on the bottom of the pot, as this negatively impacts drainage over time.
The perfect high porosity soil mix can be hard to find. Soils that are too heavy can be amended with about 1/3 –1/2 the volume of 1" redwood shavings or cedar hamster bedding. Pine and spruce shavings tend to break down more quickly, so are not ideal. Try to select hardwood chips that will last longer. If necessary, moisten the mix to reduce dust and make it easier to handle.
Use a soil mix that is lightweight and drains well. If the mix contains a large proportion of dense, absorbent material, such as peat moss or worm castings, amend with 1/4-1/3 volume of 1" cedar or redwood shavings. Water in thoroughly, using Vitamin B-1 rooting tonic in the first few applications, if desired. Once the roots have settled, we prefer using slow-release fertilizers applied to the soil surface, rather than mixing fertilizer into the soil or using plant stakes. This avoids any risk of burning the roots. Romeo fertilizer is what the trees are grown within the nursery and has proven to do extremely well on container citrus when applied monthly during the growing season.
When shopping for the perfect citrus soil mix, please avoid those that contain chemical wetting agents or fertilizers. Soil mixes formulated for outdoor use are preferable to potting mixes for indoor plants, since the latter often contain chemical wetting agents, causing tree roots to remain too wet after watering. You can start with a good rich organic soil and amend with about 1/3-1/2 volume shavings, perlite, or coco fiber. Mixes for Cactus/Citrus have a lot of sand but can work. Use your judgment to amend as needed.
Planting in Containers
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 prepared soil mix in the bottom of your new container. Gently slide tree roots out of the old container, trimming off any dead roots and detangling any circling roots so that growth into the new pot will not be impeded. If planting a bare-rooted mail order tree, gently shake the shavings loose from the roots and mix them with the planting mix. Place the loosened root mass into the new container and gently fill with your fresh planting mix, packing down lightly to remove large air spaces from the root zone. The top of the roots should be just beneath the soil surface, and crown roots (root collar area) should show above the soil line. Make sure that soil or mulch is not pushed up against the trunk of the tree. Water deeply. Stake loosely with a green tie if needed. It’s a good idea to repot every year or so, or when you see roots peeking through drainage holes.
Watering in Containers
Consistency is the key to citrus watering. Citrus trees require soil that is moist but never soggy. Develop a watering schedule so the roots maintain even moisture, but are not waterlogged. Watering frequency will vary with soil porosity, tree size, and environmental factors. Generally, once or twice a week deep watering works well for container specimens. It is 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. Elevate pots above standing drainage water. This can be done with a saucer filled with river rock.
Water before leaves show wilting, and when roots have reached about 50% dryness. Even if the top of the soil is dry, check the moisture level in the soil by probing down 4-5" down into the soil feeling for wetness. If dry, then you know it's time to water. A wilted tree that perks up within 24 hours after watering indicates the roots got too dry. Adjust the watering schedule accordingly. A tree with yellow, cupped, or leaves that don't look perky after watering can indicate excessive watering and soggy roots. Give your tree water less often.
A moisture tester can be an excellent tool to help determine when roots are in need of a drink. Because most commercial moisture testers rely on an electrical conductivity method, however, it is possible to get a misreading due to high salinity or other conditions. An alternative method recently shared by a New England citrus enthusiast simply employs a plain wooden dowel about the diameter of a pencil. Sharpen it with a whittling method (sharp knife) or pencil sharpener. Then insert this into the pot at varying depths, shallow to deeper, determining moisture using your direct senses (feel, smell, etc.).
As the previous example of an alternative moisture tester shows, indoor citrus trees inspire innovation! There is no one “right” soil mix, except all the ones that now contain happy citrus trees. People over the years and in every state have experimented, using locally available materials and resources to develop methods that work for them.
Short & Sweet Version: The goal with container growing is to provide the same conditions that the trees thrive in when planted in the ground. These conditions include well-draining soil, full sun, regular feeding, infrequent deep watering, and protection from extreme conditions/pests.
Check out our Citrus Growing Tips for more information.
Protect your fruit trees from the hot summer sun, winter cold, pests, and rodents with Plant Gaurd tree paint and foliar spray.
Get in the know about HLB(Huanglongbing / Citrus Greening Disease) and help save your community's citrus. Only source citrus trees from reputable growers.
Author Israel Osuna