Q We have been trying to buy an osage orange tree with no success. Nostalgia prompts us to keep looking. Many years ago, as impecunious newlyweds in Ohio, we made pomander balls from the fragrant orange-scented fruits and gave them as Christmas gifts. We have seen them growing while we've been out driving, but wonder if there is a special reason why nurseries do not sell them. B. E. Ballwin, Mo. Osage orange (Maclura pomifera, belonging to the mulberry family) was once used for fencelike hedges because of its vigor and ability to stand adverse conditions. Thorns and compact growth, when sheared, made it cattle-resistant. These rural assets made it a weed tree for urban and suburban areas. Michigan State University horticultural specialists have listed it with their ``dirty dozen'' landscape trees. You can start trees from seeds which have browned in the fruit. Remove and dry for a few days, then keep in airtight jar until ready to use. At that time place in refrigerator (about 40 degrees F.) for two months before sowing in moist, loose soil. Trees can also be grown from cuttings taken in late spring, either from top growth or from roots. Root in moist perlite or peat-lite mix. Be sure to atomize and water daily and keep from direct sun. Q A friend gave me a golden barrel cactus which almost fills a six-inch pot. The printed instructions were to water sparingly and grow it in a sunny place that would not go below freezing. I put it on my enclosed porch, which goes no lower than 40 degrees F. during the winter. Yellow spines are stiff and quite attractive. Although flesh appears to be firm, I notice it has developed small brown spots. Could you diagnose the problem and give more complete information for its care? J. M. D. Greenwich, Conn.
Your golden barrel cactus (Echinocatus grusonii) is getting enough sun, since spines would lack firmness and color otherwise. The problem of brown spots, called ``brown cold marks,'' indicates too low a temperature. The minimum should be 45 degrees F., but it really prefers 50 degrees F. or above. It should be kept dry from autumn until spring. Then water weekly during spring and summer -- how much depends on size of plant and how dry the air in the room. Better to underwater than overwater. If plant remains firm, you're giving it enough.
During watering period, substitute one diluted liquid feeding (high-potassium fertilizer) for one of the waterings each month. Repot once a year, in spring or summer, moving it to the next size pot. We use one part coarse sand (washed sand from a lumberyard or garden store) and one part peat-lite mix. Wait for three days before watering. Q Have you ever used redworm (or earthworm) castings for potting soil or for rooting cuttings? Our supply of potting mix was almost depleted a couple of months ago and we decided to take some of the castings out of our garbage-can composter (which you wrote about awhile back). Cuttings of an Angel wing begonia rooted a week sooner than they did in plain peat-lite mix, when stuck in half worm castings and half peat-lite mix. M. J. Redding, Calif.
We have not used worm castings in this manner yet, but we intend to.
A few weeks ago we read an item in Hortideas about some Italian scientists who found that worm castings in the medium hastened the rooting of various cuttings. Hortideas (a horticultural newsletter published by Greg and Pat Williams) asked subscribers to try the idea and report their findings. We knew earthworms benefit soil, so it makes sense.
The address of Hortideas is 215 Cedar Street, Lexington, Ky. 40508. Annual subscriptions are $10.
If you have a question about your garden, inside or out, send it to the Garden Page, The Christian Science Monitor, One Norway Street, Boston, Mass. 02115. Doc and Katy Abraham are nationally known horticulturists.