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David Ross's Garden

Dwarf Citrus in Containers

Copyright © 2004, 2006-2009, 2011, 2017-2018 by David E. Ross

I used to have my dwarf citrus planted in redwood tubs. These were cylindrical, not tapered. They were about 18 inches in diameter and 18 inches deep. Even with the tubs raised on bricks (regular bricks, not the thinner pavers that I now use) and despite the durability of redwood, the tubs would eventually begin to rot and require replacement. Not only was repotting a real bother, but the large redwood tubs were becoming very hard to find. So I finally replaced them with large terracotta flower pots, about 22 inches in diameter at the top, 17 inches at the bottom, and about 20 inches deep. Mixing sufficient potting mix for each container was quite an effort.

I now have four dwarf citrus trees, three in containers:

I had a 'Eureka' lemon (Citrus limon 'Eureka') for about 40 years. As it started to decline, several nurseries informed me that dwarf citrus in a container is unlikely to thrive more than 25-30 years. Despite two prior near-death experiences — once when I fed it while the soil was too dry and burned the roots when I then watered it and once when we had a severe frost — neither events stopped abundant crops of full size lemons on a tree that was only four feet from soil to top. We got lemons all year long, about 10-30 every year; one year (about a year after the second near-death event), we got close to 60 lemons. The tree had fruit all year long, in various stages of ripening. It flowers on and off all year long, only stopping if there is a significant frost or heat wave. This is characteristic of lemons, which are ever-bearing and have no real season.
That lemon tree finally died near the end of 2006. I replaced it in the spring of 2007 (photo ). As with its predecessor, this new tree has been producing lemons faster than we can use them. One summer, it produced so much fruit that I not only gave away many lemons but I also made three cups of lemon marmalade.
I had a dwarf kumquat (Citrus margarita, aka C. japonica 'Nagami', formerly Fortunella margarita 'Nagami') for more than 35 years, but then it died. Part of the problem was that roots had clogged the drain holes in its container; it effectively committed suicide by drowning. But the "tree" was also about 10 years older than dwarf citrus is reasonably expected to survive in containers. In October 2006, I replaced it with a new 'Nagami' kumquat. In the summer, this citrus has tiny white flowers, sometimes in two bloom periods about a month apart. In the winter it is covered with little orange fruits that are bitter, sweet, and sour all at the same time. (See also Loquats and Kumquats Are NOT the Same.)
The 'Robertson' navel orange (Citrus sinensis 'Robertson') is about 12 years old. It's about four feet high above the soil in its container. It flowers in the spring. The fruit ripens in the late fall or early winter. It bears erratically. Some years, we get about a dozen large, sweet oranges; some years, we get nothing.

Each pot sits on three, thin paver bricks arranged in a triangle. The bricks sit on an 18-inch concrete round set on the back lawn near a walkway. This elevates the bottom of the pot above the soil to allow excess water to drain.

The citrus is watered by drip irrigation tied to my automatic lawn sprinklers, which runs every third day. This is far more often than citrus in the ground should be watered. However, with their roots constrained in containers with a fast-draining potting mix, the soil must be keep moist. Even then, the foliage on my lemon sometimes outgrows the ability of its limited roots to provide moisture; when I see repeated wilting, I prune some of the excess growth.

I also have a dwarf 'Minneola' tangelo (Citrus reticulata × paradisi), a cross between a tangerine and a grapefruit. This is not planted in a container but in a raised bed in the back yard. It flowers in the spring, and the fruit ripens in the summer. However, it appears that it needs cross-pollination from a tangerine. Although there are tangerine trees in the neighborhood, it sets only a very few fruit; in some years, it is fruitless.

I feed my citrus every three weeks from early March until early October. Citrus prefers an acidic soil and requires much nitrogen, iron, and zinc. I alternate feedings with a commercial citrus and avocado fertilizer and ammonium sulfate. The commercial fertilizer is acidic and contains extra iron. The ammonium sulfate is merely nitrogen in an acidic compound; when I use it, I also add a large pinch of iron sulfate. With each feeding, I apply a pinch of zinc sulfate. Having learned a serious lesson with the original lemon, I feed only when the soil is moist. Growing in containers with fast-draining soil and frequent watering, the trees need frequent (but light) feeding to replace nutrients that quickly leach away. Feeding tends to promote tender new growth that would be damaged by the night frosts that generally begin in December. Thus, I stop feeding in October to allow any resulting new growth to mature and harden.

From March to September, I repeatedly prune the dwarf citrus, removing dead twigs and weak branches and pinching new shoots to make them bushy. This is a very light pruning, intended primarily for aesthetic purposes and — as already mentioned — to keep the foliage commensurate with the constrained roots. Citrus does not require pruning to promote fruiting (as, for example, is done for peaches). I do not prune from October to February because I don't want to encourage tender new growth.

I constantly check the trees for pests. Aphids are not usually a problem because, by the time they appear, ladybugs are also present to eat them. Spider mites and scale can be problems, but I don't see them every year. I use malathion if aphids, mites, or scale are a problem. Occasionally, I find a snail that somehow crossed the copper wire that is supposed to protect the tree; I hand-pick them.

Lately, a citrus leaf miner has attacked my trees. While their damage would not be severe on a full-sized, mature tree, they can defoliate and kill a dwarf tree. When I see the start of damage, I've been using imidacloprid (a systemic insecticide applied as a soil drench). Although its use on fruit-bearing trees is definitely not approved, studies indicate that imidacloprid is harmless to mammals.

29 March 2004
Updated 1 June 2018