QUESTION: My columbines bloomed beautifully for weeks, but then their centers began to look stepped on, their long stems turned brown and their leaves yellowed. Some new leaves grew, but they soon yellowed, too. What can I do?

ANSWER: Becoming leggy, then dying back, is common. Gardeners whose aging columbines will be hidden by other plants usually just ignore these developments. Others cut off the old growth and wait for good-looking new leaves, which usually stay healthy for quite a while.

But columbines are short-lived, and yours may simply be quitting. If plants are young and soil is poor, yellow leaves may mean hunger. Try a dose of liquid organic fertilizer. Wet soil and poor air circulation often lead to wilts and rots that can cause yellow leaves. Fungicides are not much help, but giving the plants breathing room, especially at ground level, may be enough to save them.

Worst case is a virus disease like asters yellows or beet mosaic. These have no cure and spread easily, so it is important to destroy the plants, start new ones elsewhere and consider some different species.

QUESTION: The hydrangeas that came with my house bloomed reliably for years, but not this spring. What happened and what can I do?

ANSWER: Chances are your spring-blooming hydrangeas have the same problem as other readers' redbuds, roses, smoke bushes, daphnes, lavenders, roses, lambs ears, roses, creeping thymes, roses, oriental poppies, chrysanthemums and roses. Its name is winter kill, and you can be glad you didn't lose more.

For several years, Northeastern winters were warmer than average in many places. Established trees and shrubs made lots of vulnerable new growth.

But last winter was average, and many places suffered a dearth of insulating snow. Nature does this occasionally in order to keep gardeners humble.

Address questions to Garden Q&A, The New York Times, 229 W. 43rd St., New York, NY 10036, or by e-mail to gardening@nytimes.com. Those of general interest will be published.

By N.Y. Times Service