Container-grown Cape Honeysuckle with Wet Feet

Q: A couple years ago I bought a 5 foot staked cape cod honeysuckle, (orange trumpet clusters). It is in a 3 foot tall 18 inch wide plastic container on my balcony. I live in P.B. across from the bird sanctuary, southern exposure. It grew and developed into a lush fabulous dense plant, (about 15 feet tall)  finches would make their nests and breed in it. A little more than a year ago the leaves got yellow and dropped.

My friend who also supplies me with organic fertilizer said it is the water, he was having similar problems. He planted 6 tomato seeds for an experiment. 3 got tap water, the other 3 filtered water – tap water grew to 2 inches, a bit sad looking. The plants that got the filtered water grew to about 15 inches in the same time and looked great. So I flushed the honeysuckle with filtered water.Filtered water in, sucked out the run-off and discarded it, I did this for an entire day, and cut some of its bare branches back. It seemed for a while the problem was arrested, but the tree was just existing, not flourishing. By then it lost about 75% of its foliage. 3 month ago it started again, leaves turning yellow and dropping, it looks pathetic, but still produces flowers.  I have shed tears hugging  my honeysuckle and told her how sorry I was that I don’t know how to fix this.

Your experience and wisdom are my only hope.

Answer from Pat:

It is very sad to have a beloved plant die. Fortunately, your question gave me all the clues I need to tell you what’s wrong with the plant. In a nutshell, it is not adapted to growing in a container and it has wet feet, but clearing up these problems may not save the plant. So let’s survey the facts and then look at possible solutions.

First, common names are subject to much confusion and the one you cite is incorrect. There is no plant called Cape Cod Honeysuckle, though you are not alone in using this name; it’s even on the internet. If there were such a plant it would have to be a hardy honeysuckle shrub or vine, most likely Lonicera japonica ‘Halliana’, a fragrant, white-flowered, hardy and invasive climber. (The word “hardy” has nothing to do with whether a plant is “tough” or easy to grow. Hardy applied to a plant means it is capable of going through a cold winter without dying.) The true honeysuckles are Lonicera’s. Many are fragrant but none have orange flowers. (Lonicera ‘Dropmore’ has red flowers and the rest are white, yellow, or bi-color.) Thus I know the plant you have with orange flowers is Cape honeysuckle (Tecoma capensis) and it is a large shrub which can be grown as a climber. The words “Cape” in its common name and “capensis” in its botanical name derive from the Cape of Good Hope in South Africa, where this plant is native, not from Cape Cod. This plant could not survive a New England winter on Cape Cod.

The main problem you are having is not alkaline water, but the fact that you are trying to grow Cape honeysuckle (T. capensis) in a container and it is not adapted to growing in containers.  Also the fact that you said you sucked out the runoff and discarded it sounds as if you used a bulb baster and that you have a saucer under the plant that fills up with water. If the roots of this container-grown plant are allowed to sit in water, this is a condition called “wet feet” and will kill this plant. Few plants like wet feet but particularly this one which is very drought-resistant and likes to run dry. The problem of wet feet can kill many plants, for example, a potted geranium will die from wet feet quicker than from any other problem. This can be solved by filling the drainage saucer to the very top with gravel and setting the pot on top of the gravel. Water will then drain down into the gravel and not touch the roots of the plant.

So let’s look at the characteristics of this plant. Cape honeysuckle is a large rampant shrub that can grow 20 or 30 feet tall if not frequently hard pruned to keep it lower. Grown in the ground it is a tough, easy, plant that can take alkaline water, grows well in any kind of soil, and needs little irrigation.  It likes to put its roots deep into the ground and prefers deep but infrequent watering. In coastal zones it sometimes survives with no irrigation whatsoever.

Your plant grew well at first because its roots had not filled the container. Once the roots had filled the container the plant probably got root bound. The roots ate up all the soil and went round and round. Now when you watered, the hole in the bottom might have been clogged with roots and water might have sat in the bottom of the container, thus killing roots. Or alternatively, water might have by-passed the roots altogether and run straight down around them into the bottom of the container and the saucer beneath. Either of these conditions can cause all the leaves of a plant to go yellow and fall off as you describe. It continues to flower because it thinks it will die. I have seen plants such as a dwarf Meyer lemon growing in a half barrel with this problem. It often happens to Ficus benjamina grown in a pot as a house plant.

If you were able to take your plant out of the pot and put it in the ground, it might survive. Unfortunately, your only solution now is to empty it out and try something else. For a quick cover this year, try scarlet runner beans. They bring hummingbirds. For a permanent fix, plant a shrub or climber better adapted to growing in containers. Some bamboos grow well in containers, including golden goddess bamboo (Bambusa multiplex ‘Golden Goddess’) and golden bamboo (Phyllostachys aurea). I have had luck growing angel’s trumpet (Brugmansia) in containers. I like the one called ‘Charles Grimaldi’ best but there are others that work well in containers also. Once established they need almost daily water and frequent fertilizer and bloom in waves of bloom year round.  Heavenly bamboo (Nandina domestica) is another plant that can survive in a container for some years and dwarf citrus is an elegant possibility, especially kumquat, due to its small size and dense foliage.

Regarding alkaline water, softened household water is not good for any plant since it contains more salts than ordinary tap water and these build up in soil. Most potted plants do okay with ordinary cold tap water, however, as long as the water is allowed to drain out the bottom of the plant and flow away from the roots. Filtered water is probably better as long as the soft-water company has come out annually check and confirm it is relatively free from salts. (Companies don’t do this service regularly unless a customer asks for it.)