Q. I've been trying to root some cuttings of geraniums we brought indoors a few weeks ago, but the bottom end keeps turning black in the water. The geraniums were started from seeds. Could this be why they do not root?
Seed-started geraniums root as easily as any others, but we find geraniums difficult to root in water.
We have no problem rooting them in moist perlite or a mixture of perlite and sphagnum peat moss. We sub-irrigate the rooting pot so the medium is moist at all times. Also, we keep the rooting chamber where the temperature does not go below 68 degrees F.
If you have a spot that is about 80 degrees, such as a radiator, where you can set the pot, they will root even faster. Garden stores now sell horticultural heating pads for those who want to do any amount of rooting or seed starting.
Q. We want to rig up a fluorescent-light setup in our basement for African violets. Do we need special grow lights or can we use ordinary tubes? How far above the plants should they be?
If you can maintain a nighttime temperature of 67 to 70 degrees F. and a day temperature of about 75 degrees, you can grow violets with lights. A fixture with two 40-watt tubes will be sufficient if you keep the violets within 8 inches of them. The tubes should be left on from 14 to 15 hours a day.
White-light tubes are fine. The main advantage of grow-light tubes is that they make color appear more natural. The lights will help keep the temperature at 75 degrees.
Q. We stuck rose cuttings into the soil in early September and put jars over them as your column suggested some time ago. Their leaves have now fallen off but stems appear green. Do we leave the glass jars on? How should they be protected? Temperature sometimes drops to zero in our area.
It's a good idea to leave jars on all winter. If the soil is dry, moisten it, as the roots will continue to grow even though the plant is in a dormant state.
A mulch of leaves partway up the outside of the jars may be a boon if the weather is severe. Remove the jars in the spring when the danger of frost is over and before any new leaves get crowded in the jars.
Q. We have just read an advertisement which states that a windbreak on the prevailing wind side of a house can cut a fuel bill as much as 20 percent. Do you agree? Does the ad refer to evergreens or deciduous shrubs?
We are longtime advocates for using shrubs, trees, and ground covers (including lawns) to save energy.
The 20 percent figure is for evergreen windbreaks and is reported by the National Bureau of Standards. Many times it is much higher. Princeton University found that a row of evergreens 75 feet to the windward of a house will reduce wintertime drafts inside by 40 percent.
Deciduous shrubs are very helpful, also, but somewhat less efficient as windbreaks. In the summer, shade trees and lawns can reduce the workloads of air conditioners by 50 percent, if well placed. Shade trees should be deciduous to let the winter sun in after the leaves fall.
Good landscaping with live plants reduces noise, purifies the air, recycles moisture to maintain our water supply, provides homes for birds (our best pesticides), and adds 15 percent or more to the value of the home.
Q. Two years ago we built two planter boxes on our south-facing deck. We made a soil mix of one part each of sand, garden store potting soil, and peat moss. Both summers our plants (geraniums, marigolds, and petunias) did poorly. I did not feed them this year, but did last year. We made the boxes out of pressurized lumber. Could this cause a problem?
Plants do benefit from a midsummer snack, but since yours looked poorly both summers, there is another reason.
Sometimes pressure-treated boards do contain enough chemical to inhibit plant growth. Try washing the insides of the boxes with ammonia water and letting them weather all winter; or, build a metal box to set inside the wooden planters.
Put drain holes in the bottom and line it with an inch of crushed stone.
Q. A bromeliad we've had for about four years has just put forth a pink flower spike with small blue blooms appearing from inside the pink structures. What care should I give it to keep it blooming?
Pineapples are in the bromeliad family. The one you have is Aechmea fasciata, also called urn plant or silver vase plant.
There is a cup inside the whorl of leaves that should be kept filled with water (chlorinated water should stand several hours so the chlorine dissipates).
The soil should be well drained but never dry; in other words, just moist. A good mix is one part sharp sand and one part sphagnum peat moss. Half-strength liquid plant food added about every six weeks is sufficient.
The plant needs bright light but not sunlight. When the bloom, which lasts five months, fades, cut it at the base.
New plants will appear alongside the mother plant. Soon after this the old plant will fade and die. When new plants are eight to 10 inches high, pot them separately. When they are about 18 inches tall they should bloom.