Question
Last year I was given 5 large dieffenbachia in small pots that they had clearly outgrown.  The largest was about 3' tall, the smallest maybe 2'.  I repotted all the plants to pots just slightly larger than the root balls , and have had to repot the largest one twice since due to rate of growth.  Right now the largest of them is about 5' tall from where the stem goes into the soil to the top with leaves about 2' long, and the others aren't far behind.  My question is, what is the best way to maintain these plants as they reach top growth?  They are doing well with no browning and only dropping leaves upon occasion, and I would like to keep them in top condition.  Right now they get mild Miraclo-Gro once a week, bright but diffused sunlight, and I normally water when the soil just begins to feel dry and mist at the same time (i use tap water that I let sit out for 24 hours).  Also, how often should I be repotting them--how do I know when they need it?

Thanks in advance,

Suzanne

Answer
The "dieff" can get up to 6 feet tall or more. But what so often happens is, the lower leaves fall off and you are left with about 2 feet of leaves at the top, and a long spindly stem at the bottom. It is not very attractive. There are some ways to get around the leggy look. One is to propagate the plant, by airlayering, or cuttings and start a new plant.
Or I prefer the pruning method. I simply cut the plant back to about six inches above the soil line. The plant will then resprout with multiple stems. I know cutting is difficult, if the plant is doing well. So it will be up to you when you think this method of "refurbishing" is necessary. They like to be "root bound" in the pot, so watch for the roots to begin pushing the plant up in the pot. Carefully take it out of the pot, and check the roots. You will want to see roots on the bottom of the soil, before you pot up. Once repoted, it usually sends up new basal shoots. Potting soil should drain freely. Feed bimonthly in spring and summer with half-strength liquid fertilizer. They will not withstand constant overwatering, so it is better to underwater, then over. Water less in winter dormant period. Sudden change from low to high light will burn the leaves. However they will benefit from outdoor, protected light, in the summer. No direct sun. Keep out of drafts, and away from heat ducks. These will cause browning on the leaves.
The benefits of misting are quetionable. I have never misted mine, and don't see any problem because of it.
Watch for aphids. They attact suddening, and can be a real problem.
Remember the plant is poisonous, so use caution when pruning, or coming in contact with sap. That is why it is referred to as "dumb cane" If it gets on your vocal cords you won't be able to talk.
The leaves will naturally turn yellow and die back. Don't be alarmed when they do. But, because of this, it is often difficult to tell when the plant has problems. When you do see yellow leaves, check the plant carefully, if you don't see anything, then continue as you have.
Staking may be necessary when the plant gets too large to hold itself up.

bakerplanter