Growing Concerns 536: African violet with long neck

Early Fall!

Repot that African violet when it sticks its neck out

Dear Janet,

I have no problem growing large (10-inch diameter) African violets. My problem is the dropping of bottom leaves after the plant is about 3-4 years old. The leaves still look very healthy but the stems get soft. I've lost so many leaves, the crown is long, bare and hangs to one side.


Dear H.,

I'll let The Royal Horticultural Society Dictionary of Gardening (Stockton Press, NY) answer for me:

"As a plant matures a 'neck' develops when spent leaves are removed from the main stem. Repot... by cutting away the bottom third to a half of the rootball thus lowering the plant into the fresh potting medium for new roots to grow from the main stem."

"When the neck is too long for this treatment cut through the main stem an inch below the leaves, trim the stem below the leaves into a cone shape and pot into a small pot with the leafstalks just clear of the potting medium. Place the pot in... bright indirect light at... high humidity such as in a covered... propagator."

Now, for that other question -- "Why?" (Thanks to R.A.  for reminding that there are always people out there who will also add "why?" after asking "how?")

The neck develops because this plant from tropical Tanzania in Africa evolved in an environment where soil is always building up with rotting plant debris. The continually growing, dense rosette must lose bottom leaves as they become too shaded by new growth to be productive. As the plant drops leaves it also rises, keeping itself above all the leaf litter that accumulates on a rain forest floor by means of its elongating stem. As each point on the stem that once grew a leaf is enveloped in cool, moist organic matter, the point is stimulated to resume growth. Roots form there.

To grow these plants in pots, we simulate the condition they have evolved to need -- increasing soil level -- by repotting, deeper.

Coral bells (Heuchera species) and some other woodland natives that we grow in gardens follow this growth pattern, too. If we grow them in a place where the soil level has to stay the same year after year, we give them the same treatment, digging them up to replant them deeper every few years.


Dear Janet,

Is it okay to use a kill-all product to edge a flower bed?


Dear J.,

It's acceptable but I don't recommend it. It doesn't  meet my standard for a flower bed because it can't make a neat straight edge like a cut. Also, weeds on that edge are highly visible as they yellow and die. That's not what I want to see on the front edge of my flower beds.

Herbicide as edging is hard to control. The herbicide can drift or splash onto desirable plants, which tend to die more readily than the weeds. Most people don't even know any weed killer has drifted until they see the dead flowers. Yet this tactic is widely employed in places where labor is in short supply, such as at arboretums. So if you're careful and will accept some collateral damage, it can work.

Your term "kill-all" concerns me. I hope you aren't thinking about using one of those products that kills anything that tries to grow in a spot and is effective for a whole season with one application. For edging, use a product such as Round-up (active ingredient glyphosate), which kills what is growing there now but doesn't affect what sprouts there later. Round-up is absorbed through foliage, not through the root.

Season-long killers poison the soil itself. Those like Triox Total Vegetation Killer (active ingredient Prometon) move from soil into the root and have long lasting and often unexpectedly wide impact. For instance, if there are trees whose roots occupy the same space where you poured something root-absorbed and long-lasting , then that tree is likely to lose some branch tips or limbs, or die. Ditto for shrubs with roots in the area.

Always read the label on a pesticide before applying it. Be sure any herbicide you intend to use for edging says an area may be replanted immediately after application. Heed warnings! The label on Triox explains that it shouldn't be used over the root systems of desirable trees and shrubs.

How to know what other plants have roots in the area? Look up. If you are anywhere near the outer ends of the branches, then you are standing on that tree's or shrub's roots.

Short report

Still okay to seed a lawn.

M.J.  needs to reshape a lawn to add to the edges and wonders if it's too late to do this by seed.

Although we're past prime lawn-seeding time, seed you spread now will probably still germinate and take root. Remember to give it a sprinkler assist on any hot, dry days.


Green thumbs up

to mowing the leaves as they fall and letting them stay on the lawn. This replenishes the soil, returning to the earth nutrients used in making those leaves. You'll rake less and the grass will benefit.


Green thumbs down

to dousing houseplants with pesticides unless there is a visible need. As you bring them in from outdoors they are the healthiest they ever are! Just rinse the foliage and wipe down the pot.

Originally published 10/4/03