Growing citrus trees in containers has become very popular in recent years. Having a citrus tree indoors is considered to be very exotic in some circles. Not only do citrus trees add a green freshness to a room, they also add beautiful flowers, great fragrance and, with any luck, many years of fresh fruit for your enjoyment.
Dwarf Citrus Fruit Basics
The only citrus trees you should consider for containers are the dwarf varieties. These trees are bred especially for container gardening. Dwarf fruit trees are derived from a process known as grafting. A tree is grafted by inserting the stem of a citrus tree onto the roots of another tree where they are fused together until they are one tree. The bottom section of the graft, or the rootstock, is selected for its dwarfing properties, while the top part of the graft is selected for its fruiting capabilities.
You will see a scar or node where the grafting has been done. If you see a branch growing from below the graft this process is known as “suckering”. Be sure to prune all suckers off completely as these will quickly drain vitality from your tree. These suckers are especially vigorous on young trees so be very vigilant about removing these branches.
When you purchase plants for growing citrus trees in containers you can buy either potted trees or bare root specimens.
Types of Citrus Trees
When growing citrus trees in containers, the best types of citrus fruit to consider are the fruits that are naturally sour such as lemons and limes. These are easiest to grow indoors if you are growing the fruit for an edible crop. These sour fruits are possible to grow in all types of weather and still harvest an edible crop. This is because they don’t need such a long period of heat to develop sugars and can also thrive on less sunlight.
If you live in a warmer climate, it is possible to grow the higher sugar citrus fruits such as oranges, grapefruits and tangerines if your containers can be left outside for a longer growing period.
The varieties Meyer Lemon and Bearss Lime are recommended as the easiest dwarf varieties to grow and are a good place to start if you are new to growing citrus trees in containers.
Choosing Soil for Your Container Fruit Trees
Citrus trees prefer a very rich acidic soil. Commercial rose garden potting mixes work well as do mixes formulated for rhododendrons. The use of garden soil is never recommended. If you prefer to mix your own potting mixture, you can mix 1 part clean sand, 1 part peat and 1 part pine bark. Redwood shavings or cedar hamster bedding can be added to a soil that is too heavy with not enough aeration.
Choosing a Pot When Growing Citrus Trees in Containers
A 6-9″ pot is recommended for a first year tree, while a a 15″ pot is better for a 2-3 year old tree. As the tree grows, when it is time for re-potting, keep increasing the pot size up one size if you want a larger tree. Fertilize it as soon as new growth appears. When you reach the ideal tree size for your location and it is ready for re-potting, cut about 1/4 of the roots off and pot it in the same pot with new soil. Once it is potted and settled, prune about 1/3 of the foliage from the tree.
Do not start with a pot that is too large as it makes soil moisture levels harder to control with small trees
Redwood and terra cotta are attractive containers for growing citrus trees in containers. However, they are heavy and if you plan on moving your containers each season, you may want to consider using an attractive plastic container. Another alternative is to use your preferred type of container and place it on a trolley to make moving your tree about easier.
Prepare Your Container for Planting
Whatever container you choose, be sure there are sufficient drainage holes in the bottom of the pot. If there are none, or only one, drill more holes before you start your planting. The usual recommendation was to put a layer of gravel or stones in the bottom of the pot. This is no longer recommended as it’s been discovered that this is a place where water collects away from the roots. It also takes up space needed by the root system. It is better to cover your drainage holes with screening or a coffee filter.
Be sure your pot is clean and sterilized by soaking it in a bleach solution of 10 parts water to 1 part bleach for 15 minutes. Do not soak terra cotta pots in bleach solution
Planting Your Bare Root Citrus Tree in a Container
If you have purchased a bare root tree and you can’t get to it right away, set it in a bucket of water for 2-3 days to rehydrate the roots. Even if you are going to plant it right away, still put the plant in water to keep the roots moist while you are preparing your container. Check the plant roots. Untangle the roots and cut off any dead or damaged roots. Trim off any overly long roots so that the roots are about the same length.
Fill you container to about 1/4-1/3 full of your chosen potting mixture. Make a mound from the mixture in the center of your container. The mound should end about an inch or so below the rim of the pot. Place the tree atop the mound and splay the roots evenly over the mound. The crown of the plant (the spot above the highest roots) should be just below the rim. Adjust the mound if needed. Cover the roots and add more soil if needed, tamping lightly as you go to remove any air pockets from the soil. The top of the roots should be just beneath the soil surface. The crown should show just above the soil line.
Now is the time to add a stake to stabilize your tree if you feel your tree needs one. Water thoroughly to settle the soil. Wait a while to give the soil time to settle, then add more soil if needed.
Proper Watering of Your Citrus Tree
Citrus trees require soil that is moist but never soggy. Consistent watering is key to growing success with citrus fruit especially when you are growing citrus trees in containers. Shallow watering is never a good procedure for citrus. Deep watering is the way to go as this promotes root growth and strengthens your tree.
Don’t water your tree just because the topsoil is dry. Check the moisture of your soil down to the root level. A large chopstick or other sharpened stick is ideal for doing this. Insert the stick to see where the dryness ends. This way of checking soil moisture was taught to me years ago by my grandmother and I swear by it. You can tell from looking at and feeling the stick how far down the soil moisture is and if you need to water your container or not. You can also purchase a moisture meter at your local garden supply or nursery store if you have lots of containers and would like a more accurate reading of your soil moisture level.
It is best to water your citrus tree in the morning. However, if your tree has wilted, water it immediately. If it perks back up, you have allowed too long a period between waterings and your roots have dried up. To keep your plant growing well, decrease your times between waterings. If you have yellowing, drooping or dropping leaves, this can be a sign or too much water and soggy roots. In that case, increase your time between waterings.
Check to be sure your container is draining properly. Citrus roots are very susceptible to root rot and of being smothered by soggy soil especially when you are growing citrus trees in containers.
One last caveat: Be careful not to wet the trunk while watering
Fertilizing Your Citrus Trees
Citrus trees are heavy feeders. Your fertilizer should be heavy on the nitrogen. Look for at least a 2-1-1 formula. Also look for fertilizer that is formulated for citrus fruits. This would be an acidic based formula. A fertilizer formulated for rhododendrons would also be appropriate. Slow release fertilizers work well with citrus fruits in containers.
As a rule, your trees benefit from a monthly application of fertilizer when growing citrus trees in containers. Be sure to check your chosen fertilizer recommendations on the package. An occasional feeding of fish emulsion 2-3 times a year is also a good idea for keeping your plants green and growing.
Locating Your Citrus Tree Outdoors
Citrus trees grown outdoors need strong light, fresh air, and as much heat as they can get. Filtered light shade in the afternoon will help prevent sun scald. To help citrus get the heat it needs, place it where it can absorb reflected heat; sidewalks, patios, walls, or near houses help create a warmer climate for your trees. In order to reduce excessive heat and prevent stress on the roots, the use of pot feet is recommended. Never place your trees near a sprinkler where it will get frequent shallow watering. Be sure your plant never sits in standing drainage water.
Locate your tree in your chosen spot. After a few weeks, you should be able to tell if your plant is doing well in that location. If you don’t see signs of growth, or if your plant is obviously unhappy, move it to another location.
Pruning Your Citrus Trees in Containers
Mention pruning a tree and many gardeners will feel their eyes glazing over. Pruning a citrus tree is not a big deal, but since the fruit sets on new growth, you will want to encourage new branches to grow. Pruning is also useful to keep your plant looking fuller and helps eliminate leggy unsightly branches.
Pruning citrus trees can be done any time of year when you are growing citrus trees in containers. Starting about the third year, cut back all new branches to about a third of their length. Also regularly cut off weak or unsightly branches to keep your tree looking full and neat.
Pollinating Your Container Citrus Trees
Citrus trees are self-fruitful indoors. This means they don’t need 2 varieties to pollinate. Neither are bees necessary for pollination. Studies indicate however, that pollination increases fruit size. This doesn’t mean that you have to import bees into your living room. You can pollinate your fruit blossoms yourself.
Use an artist brush or cotton swab and gently pass it along the yellow pollen-covered stamens until the brush is coated with pollen. Touch the brush to the central stigma and voila, you’ve just pollinated your citrus plant. If you’re not sure where these parts are on a flower, check out this diagram of the Anatomy of a Flower to better understand these directions.
Overwintering Your Citrus Trees
You can leave your trees outside until the nighttime temperature drops to about 45 degrees. Gradually acclimate them to get them ready for moving inside. Start about three weeks ahead of time to gradually move your tree into more shaded areas. You can also move it into a sheltered spot such as a garage for about an hour a day to help get it acclimated to being inside. This process is called “hardening off”.
Your tree will need a least 6 hours of full sun per day. Place it in the sunniest location you can find. A large south facing window is ideal. If there is not enough light for the tree, supplement the light with artificial lighting. You will also find indoor trees require less frequent watering so adjust your watering schedule at this time.
Once spring arrives, you can move your tree back outside. Reverse the “hardening off” process to get the trees acclimated to being back outside.
Harvesting Your Fruit
Most citrus bloom in the spring, but the ripening times can vary greatly. If fruit develops the first year, you should pinch off all but 4-6 fruits to encourage leaf and stem development. Generally a 2-3 year old tree will bloom in the spring if given adequate light, water and fertilizer. Each year as the tree grows; it will have more fruit producing capacity.
Growing Citrus Trees Takes Patience
As you can see, it takes a while to get a good crop of citrus fruit. In the meantime, however, you get a beautiful ornamental plant of great beauty and fragrant flowers. What more could you ask for as a reward for your patience?