Growing Concerns 601: Christmas cactus, miniature rose, white dust


Spindly Christmas cactus won't look better unless light is increased


Dear Janet,

I have several leggy Christmas cactus plants. I would like to start new plants from them as gifts to family and friends. They're healthy, just not as dense as ones I see at nurseries. What should I do?


Dear A.,

Start new Christmas cactus from cuttings two- to three leaf segments in length. Air-dry these for a day in a cool, dim spot so callus forms on the cut surfaces, then stick them in potting mix. This is best done in early spring.

 Density is a product of high light. Your new plants will be as leggy as their parents unless you give them more sun or grow lights -- light that's brighter, for more hours per day.

Professional growers know light is essential and provide lots of it. Without a greenhouse plus supplemental light you may never produce plants as dense as the pros do.


Dear Janet,

I brought my plants indoors last fall. They are doing very well. My miniature rose is blooming beautifully but I notice it has white dust all over it. What home remedy can I use to spray it?

Also, my ivy is getting aphids. I have rinsed them off but am not sure what to treat them with. I used to have a recipe for insecticidal soap and cannot find it now.


Dear L.,

Dust? Or powdery mildew? Cornell University tested and saw satisfactory (though not stellar) control of mildew and blackspot on roses using baking soda, soap and water. Use a tablespoon of baking soda in a half-gallon of water, plus a teaspoon of oil-based soap such as Murphy's Oil Soap.

No fungicide, from kitchen or store, can fix leaves already infected with a fungus. Those may yet die. Fungicides protect still-healthy leaves and emerging foliage from infection.

Outdoors, this spray must be reapplied after every rain but indoors you can spray every few weeks or as new foliage emerges.

Fungicides can burn. So move plants out of bright light while you spray and until the solution dries on the leaves.

Put your rose in better light. A rose in good light can fend off some fungi on its own.

You may be able to control aphids by simply flushing them away. Being knocked off its plant is almost certain death for an aphid, as each individual did not and cannot "find" a feeding site on its own. Each aphid was laid in place as an egg, by a winged adult that did have that ability to locate a good leaf, or it was birthed live by an aphid already in place on a succulent shoot.

You can add soap to your spray -- 1 to two teaspoons per quart of an oil based or citrus-based soap -- Murphy's, Lemon Joy, etc. Soap is a drying agent that can kill aphids and other soft-bodied insects. If you use soap solution, cover the soil surface so soap can't soak into the potting mix.

Rinse more than once to control an aphid infestation. Eggs can't be washed off or killed so easily as insects can. Eggs left behind after the first rinse have to be knocked off after the young emerge. If you rinse the plant well, three or four times at five day intervals, you may beat the aphids.

Let soapy solution sit on the foliage (and the insects) for 20 minutes. Put the plants in a bathtub to spray them, or spread a drop cloth below them so they can drip all they must. Then rinse the plant and put it back in its place.

I learned this from Jane Suhail, who has done wonders in her career at Planterra Greenhouses in West Bloomfield, caring for interiorscapes with just such simple, effective tactics.

Short report

You can transplant that live Christmas tree to the yard.

Yes, M.K.  it can be done. Dig the hole now -- the ground is not frozen in many places under the insulating snow. Then acclimate the tree to the outdoors before you plant it. Put it in a cold room for a week, then in an unheated building for a week or more, all the while keeping moist rags around the root ball. Groundhog Day might be your planting day.


Some problems have no solution. I can't provide much help to those who pose a "stumper" such as:

Why does the branch that needs pruning or weed that needs pulling show itself only as we are backing out of the driveway, on deadline?


Green thumbs up

to fragrant plants. I shovel the walk, bump the feverfew and thyme, and my nose knows spring.


Green thumbs down

to Home Depot for selling houseplants without providing a way to keep them alive as they leave the store. They'll die on the trip home unless you wrap or bag them to trap some warm air around them. Plastic bags can't do it. Kudos to the manager who offered to cut down a yard waste paper bag for this purpose and assured me it can always be done if the buyer asks. Yet that presumes the buyer knows to ask and can't excuse that cashiers aren't trained to offer.

 Originally published 1/15/05