Ask The Gardeners. Q&A.

Q. A few years ago we bought several hybrid garden roses, one of which was an outstanding pink. This year, to our surprise, the flowers are single, small white ones. Could you explain this change of color?

The hybrid part of your bush may have winterkilled. Most commercially grown roses are propagated by inserting a bud or graft of a rose onto a rootstock of a sturdy but less desirable rose, such as Rosa multiflora. Your rootstock is the white variety of this rose which has sent up shoots from below the bud union.

Examine your other roses to see if suckers are coming up from below the bud union. If so, remove them.

If there are some green shoots coming from above the union on the rose in question, then some of the hybrid still remains alive and you should cut off those from the rootstock and leave the bush in. If all wood above the bud union is brown, then remove the whole bush.

Even though you may consider the multiflora rose blooms attractive, the bush becomes very rank and thorny. It is often sold for living fences to keep livestock confined and provide habitat for wildlife.

Q. We have a green shrubby bush with glossy green, oval leaves, about an inch long, which we call euonymus. It stays green all winter and has red berries. A friend has a bush that is completely different which he also calls euonymus. It is deciduous and has flaming red leaves in the fall. After the leaves drop, red berries stay on most of the winter and the stems are quite strange looking with flat ridges.

You have Euonymus Fortunei vegetus, a very hardy evergreen shrub that can be grown as a vine or bush. It is also called evergreen bittersweet, but is not actually bittersweet. It is so-called because of the berries.

Your friend has Euonymus alatus, or burning bush. The red berries attract birds and it too is very hardy.

Q. Some time back you had a formula containing borax and Epsom salts which could be used to make muskmelons sweeter. I misplaced the article and wonder if you could repeat the proportions. Also, could you mention some ways to tell when the melons are ripe?

The proportions are: 61/2 tablespoons of Epsom (magnesium sulfate) and 3 tablespoons of borax to 5 gallons of water. Spray it on the plants when the vines start to run and again when the melons are about 2 inches in diameter. The formula is to offset a flat taste when the soils lack sufficient magnesium or boron. Remember, too, that cloudy weather can be a factor.

Tips for telling when to pick the melons are: yellowish-green color on the skin and netting that has become rounded, as well as the ''half slip'' test when pressure is applied to the stem.

Press lightly on the stem with your thumb where stem joins fruit. If the disk slides off with just a little resistance, the melon is ready. If it clings fast, wait a bit.