ASK THE GARDENERS. Q&A.
Q During April, I potted some dwarf dahlia tubers and some caladium tubers. I placed them on our sun porch, which may go to 55 degrees F. on cool nights, but never below that temperature. Our dahlias have sprouted and are coming along fine, but our caladiums haven't shown a single sprout, and some are rotting. All are potted in a mix of half garden soil and half peat moss. Could you tell me why the dahlias sprouted and not the caladiums? The tubers appeared to be firm at the time I potted them. While dahlias will sprout if night temperature goes to 55 degrees F., caladiums need between 70 and 80 degrees F. Below 70 degrees F. for any length of time they are likely to rot. Move remaining firm tubers to boxes of moist peat moss or vermiculite, with tips just sticking out. and keep temperature between 70 and 80 degrees F. (Some folks use a horticultural heating pad or cable under the box.) Keep medium moist at all times; when adding water be sure it is warm. Q I grew gladioluses for the first time last year and they were spectacular. Several of the corms I dug last fall had small bulblets form around them. I removed these before planting the larger corms. If I plant them this year (they are about the size of large peas), will they have any blooms? How deep and how far apart should I plant them?
These bulblets (called cormels) should be planted about 2 inches deep and can be set as close as 15 to a foot. Care for them as you would the large corms and some will flower next year, although most will be flowering size the year following. Q A friend would like a grapevine like the one we have on our grape arbor. He said he read a short article that mentioned that grapevines could be started from layering, but there was no explanation of what the process is all about.
Layering means that a vine or long stem of a plant is bent down, and at a selected point a small section of it is pegged down (usually in a shallow, dug-out spot), then covered with soil. The stem is notched at the point where it makes contact with the soil. Grapevines can be layered anytime, but most growers prefer to do it in late winter (pruning time), using vines formed the previous summer, which are about pencil size. Select a point 10 to 15 inches below the tip, then with a knife make a slight notch in the stem an inch below a bud. Cover that portion with soil, but let the tip stick up above ground. After a few months, roots will form and the rooted section is cut away from the mother plant and transplanted to its new location. Commercially, most grapes are propagated from 10- to 15-inch cuttings taken at pruning time.