An avocado plant will grow straight for the ceiling: it’s very reluctant to branch. Source: www.reddit.com
Have you ever noticed that certain houseplants branch abundantly, all on their own, growing nice and full, while others just grow straight upwards, without a branch to be seen? The latter are often cutest in their youth, when they’re still fairly squat or have lower leaves covering the upright stem, but then become lanky as they mature.
Often these species—such plants as the avocado (Persea americana), false aralia (Dizygotheca elegantissima, now Pierandra elegantissima), schefflera (Schefflera actinophylla), rubber tree (Ficus elastica) and money tree (Pachira aquatica)—grow as forest trees in the wild: they’re genetically programmed to stretch upwards until they make it through the shady forest understory into the sun, then they start to branch. They don’t seem to realize that, in your home, the best light is in the lower to middle reaches and they’ll only find disappointment (and the ceiling!) if they continue to grow upwards.
Then there are other houseplants that, without necessarily being forest trees, only begin to branch after they bloom for the first time … which, since indoor conditions are rarely equal to what they would have received in the wild, can be years away. That’s the case with such plants as the mother-of-thousands (Kalanchoe daigremontiana) and the Madgascar palm (Pachypodium lamerei). (The latter, I hasten to point out, is not a true palm, but in the dogbane family (Apocynaceae).
Others, though, just seem to be naturally branchless, even at maturity. The Chinese evergreen (Aglaonema spp.) and the cane dieffenbachia (Dieffenbachia seguine) fall into that category.
What to do with such reluctant branchers?
Look for Self-Branching Cultivars
Sometimes plant hybridizers have helped home gardeners by developing self-branching varieties. The old-fashioned coleus (Coleus scutellarioides, syn. Plectranthus scutellarioides and Solenostemon scutellarioides) used to be a very reluctant brancher, but most modern varieties ramify abundantly. The same goes for the zonal geranium (Pelargonium x hortorum): most modern varieties produce lots of branches. There are even basal branching varieties of the old “straight-to-the-ceiling” dieffenbachia (Dieffenbachia spp.) if you look a bit and even a branching form of the Madgascar palm (Pachypodium lamerei ramosum).
Off With Their Heads!
Normally, though, if you want to stimulate branching, a bit of pinching or pruning will be necessary.
Once you cut off the top of a plant, either only its terminal bud (by pinching) or a few inches of stem (with pruning shears), this will inhibit apical dominance, a hormonal control that tells the plant not to branch, freeing dormant buds lower down on the stem to begin to develop. Sometimes this only results in a single new stem being formed (the avocado, for example, is very reluctant to branch), but if you repeat it, you can often get a second stem at least. And, as new branches develop, you’ll probably need to “clip their tip” after a year or so to force them to branch as well.
Don’t be afraid to try! You can chop the top off just about any houseplant that has an upright stem … except palms. True palms simply don’t branch (except under very rare circumstances, not likely to occur in your home), although some do produce offsets at their base. So, leave palms alone and feel free to cut back everything (and I do mean everything) else.
The More, The Merrier
For a quicker fix, try planting several reluctant branchers together in the same pot. This will give them a naturally fuller look that can last for years. Nurseries regularly do this with such plants as Chinese evergreens, false aralias and dracaenas (Dracaena spp.). When these plants in shared pots do begin to look ungainly, just cut the top off all of the stems and they’ll all resprout from lower down, re-establishing the dense look.
Yes, you can prune or repot most houseplants to get them to put on the dense growth you want … or you can just let them grow in their usual awkward beanpole way until the ceiling interferes. You choose!