Gardeners who live in colder areas and travel to the south are always impressed with the various citrus trees they see growing. Maybe it’s the heady perfume when they are in bloom, or the beauty of those ripening fruits hanging among the rich-green leaves, but growing these trees holds a definite fascination for northern gardeners. Although some grow into trees that are too large for pots and planters, many others are small enough to be grown in pots with the right care and conditions.
What Do I Need to Grow Citrus in Containers?
Even the smaller citrus trees can reach six feet or more in height, so good-sized containers are the first thing needed. Rather than plant a small tree directly into a large container, start off with one that is a few inches wider than the pot your tree is in and change it every year to a slightly bigger size until you reach a 18-24 inch diameter pot, where your tree will grow happily for years. The pots must have drainage holes, which should be covered with a small stone, a piece of broken pot or a piece of screening, so that the soil doesn’t wash out. The pot can be plastic or clay, but remember that while clay pots need more frequent watering, plastic pots can hold too much water, especially in colder weather, and more care not to over-water is needed.
For soil, the best choice is a soil for outdoor pots, if you can find one. Otherwise mix regular house-plant potting soil half-and-half with regular cactus soil, as citrus like good drainage. Whatever you do, do not use garden soil, which will not drain properly and can carry root diseases. Fill the pot completely with soil; do not put gravel or other things in the bottom, just a cover for the drain hole.
Next you need a sunny location for your tree to grow outdoors. The more sun the better, but citrus will tolerate a little shade for a couple of hours of the day. Most citrus trees do not take any frost –although some we will describe later do – so you will need a place to keep your tree when the weather falls below freezing. If this is just for a few days a year any place that stays warmer will do, even without light, but if it is colder for longer you need a well-lit place for that time. This could be an unheated porch in milder areas, but in colder places you will need some heat. It is best if the spot is quite cool, maybe 40-45 degree or so, but most people have to keep their trees indoors where it is much warmer. The warmer the room, the more light you will need, as your tree will keep growing in a warm spot.
Taking Care of Citrus in Containers all Year Round
Citrus trees have a long growth cycle. They flower in spring while also sending out new growth. The fruit do not ripen until some time during the winter, depending on the exact type of tree. If you have to bring your trees indoors in the early fall, you will need a south-facing window for them to grow in so that the fruit will have sunshine to ripen it.
Once the weather in spring becomes warm enough, move your trees outdoors. If they have been in a cool place then this can be as soon as the night temperatures are close to 40 degrees. Nights should be closer to 50 degrees if they have been in a warm place. It is better to move your trees outdoors early and then perhaps have to bring them in over-night if there is a cold night, rather than wait for perfect weather. The more time they spend outdoors, the fewer pest and disease problems you will encounter.
Once they have been back outdoors for a week or two, repot them into a larger container if needed, or add some fresh compost to the pot if the old compost has shrunk and roots are showing. This is also a good time to add a slow-release fertilizer, preferably one for citrus trees. In addition, most growers use half-strength liquid fertilizer once a week during the growing and flowering period of the early part of the year, until the new leaves are mature and leathery. After that the slow-release will be sufficient, or a liquid feed once a month. Don’t fertilize at all during the winter months and reduce the watering.
Let the soil become a little dry between each watering. In winter allow the soil to become quite dry, in spring and summer just a little dry. Always water until excess water comes out the drainage hole and if you use a saucer, remember to empty it shortly after watering your tree.
Citrus trees don’t usually need much pruning, but you can take the tips off new growth once it has matured and remove some older branches if needed. Prune so that you keep your tree open for the sun to penetrate to ripen the fruit – don’t make it dense and bushy.
Some Citrus to Grow in Containers
If you have never grown a citrus tree before, it is best to start with something hardy and easy to grow. Here are some suggestions, starting with the easiest and working up the scale.
This is the hardiest and smallest of all the citrus trees, surviving down to 15 degrees Fahrenheit, so growing outdoors in zone 8 and needed only a short period of winter shelter in colder areas. If you have it indoors however, don’t move it outside when the temperature is below freezing – the sudden shock will damage it. The Nagami Kumquat is a unique tree that will grow to around six feet in a container. It flowers profusely and produces hundreds of bite-sized fruits that ripen in mid-winter, usually in time to make a great Christmas decoration. The fruit has a unique sweet/sour taste that is addictive fresh and also makes great preserves and jams, as well as flavoring for a bottle of vodka.
This is the hardiest of the sweet citrus, surviving 15 degrees at least for a few hours, so it can be grown outdoors in many cooler regions. Since it only makes a small tree or bush it is also great for container growing. It is easily peeled for eating right from the hand, ripens by Christmas and will be a real family favorite.
Calamondin Orange Tree
Although the fruit of the Calamondin Orange Tree is orange colored, it is flavored more like a lemon and can be used anywhere lemons are used. Unlike lemons, which need warm conditions, this tree can stand the occasional overnight temperature of 20 degrees with no problem. It will grow well in a large container and is tough and pest-resistant. It flowers several times a year and often has fruit and flowers at the same time, so a steady supply of fruit for most of the year is normal.
Although not cold-hardy, the Meyer Lemon is a small tree, so easy to grow in a container and it is otherwise tough and pest resistant, so it makes a great choice. It has a special flavor a little sweeter than regular lemons and is popular for gourmet recipes.
The Tangelo Tree
This unusual citrus was developed in the USA early last century and is the easiest of the larger citrus fruits to grow. It is a cross between a grapefruit and a tangerine, with sweet, juicy flesh that is easy to peel.
Regular limes and lemons are the hardest citrus to grow, with oranges and grapefruit coming next, but as you can see, there are lots of choices for easier trees to start a collection of citrus growing in pots.
Remember that growing a citrus from seed is about as successful as buying a lottery ticket. Centuries of breeding has gone into producing these special varieties and seedlings will take many, many years to flower and will never produce quality fruit. Buy your trees from the Tree Center and you can be sure you get the very best quality and exactly the variety you want to grow, with all its special features.