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.