ASK THE GARDENERS. Questions & Answers.

Q I have a beautiful flame-colored Christmas cactus. It blooms profusely, but not for long. In a few days, blossoms go limp and wet looking. I then pull them off. The stalks seem more limp than most of the pretty ones I see. I wonder what I am doing wrong. Mrs. L.L.H. Winston-Salem, N.C. There could be three reasons holiday cacti would behave in the manner you describe: underwatering, overwatering, and/or high temperatures. Plants are more apt to dry out when they are in bloom, since transpiration (plant sweating) is much greater. Gardeners often do not recognize this, and then leaves droop and flowers flop. High temperature has the same effect, so keep temperature between 60 degrees F. and 70 degrees F., if possible. They even do well at 55 degrees F. These plants need a well-drained soil, and when not in bloom should be watered sparingly. There is more danger of overwatering if the plants are in plastic pots, since these are not porous, as are clay pots which allow water to evaporate through sides. Overwatering will cause stems to rot at soil level. When plants are blooming, soil should never be allowed to dry completely, but kept ``just moist'' all the time. Reader Comment: A while ago you had an item about eucalyptus in your column. I enclose pages from the catalog of J.L. Hudson Seedsman, Box 1058, Redwood City, CA 94064. Many of their seeds are cold hardy, but since they are a California company, they also offer exotic and tender plants such as acacia and eucalyptus. E.S. Bronx, N.Y.

We also received an address from R.W. of Los Angeles, Calif., which is as follows: Survival Shop, PO Box 42216, Los Angeles, CA 90042 (Attn: Ray). The two seed houses we mentioned in a previous column are: Park Seeds, Greenwood, SC 29646 (varieties especially for potted plants), and Thompson & Morgan, PO Box 1308, Jackson, NJ 08527 (varieties for outdoors and indoors). Some varieties may tolerate temperatures to minus 12 degrees F. We thoroughly enjoy the potted ones indoors. Reader Comment: Your article on pennyroyal as a mosquito repellent prompted us to try it for other things. We immediately bought some pots of it at an herb seminar. We kept some indoors and planted some outdoors. We have used pieces of the viney stems in our dog's bed, replacing with fresh every few days. We did not have a single flea during the flea season, and still do not have any. G.M. Quincy, Ill.