'Hardening off': the secret of keeping cut flowers fresh

Q. We have a potted gardenia that has about 20 blooms. I picked three blooms and made a corsage for my friend's birthday, but the flowers became droopy an hour or so later. How do florists make corsages stay fresh-looking?

Before the flowers are used in corsages (or any arrangement), they should be ''hardened off.''

This means putting them in warm water, halfway up the stems, and setting them in a cool place for two hours or more.

This allows the blooms to take up moisture so they can remain turgid for several hours.

Short-stemmed flowers, such as gardenias, can be set in the home refrigerator if there are no fruits or vegetables near them. These give off ethylene gas, which puts flowers to sleep.

Ferns or other greens used in arrangements should be hardened off as well.

TQ. Recently I saw a recipe that mentioned substituting Jerusalem artichokes for water chestnuts, saying these were easily grown in the home garden. I can find no catalogs that list them.

Jerusalem artichokes are not artichokes, and they don't have anything to do with Jerusalem.

They are truly a native American plant, growing in most areas of North America. Also called sunchokes, or girasole, they are related to and resemble sunflowers with small blooms.

The edible tuber is similar to a knobby potato, but it is devoid of starch. Taste is similar to water chestnuts, and they can be used cooked or raw.

Once established, they will take care of themselves. They do best in full sun , but ours do give us a fair harvest with six hours of sun a day.

Under dry conditions or in areas of very cold temperatures, a mulch is helpful.

Two sources come to mind: Burpee Seed Company, 300 Park Avenue, Warminster, Pa. 18974; and Geo. W. Park Seed Company, Greenwood, S.C. 29647.

Q. We have a crab apple and a mountain ash tree about 15 feet apart (both 6 years old). When raking leaves we noted each had, near the bases of trunks, a pile of wet, sawdust-like material. Upon probing further, we discovered holes going up into the trunks.

Is this borer injury? If so, what can be done?

Your description indicates round-headed apple tree borer, which may also attack hawthorn, peach, plum, shadbush, quince, and pear. Adult beetles, white underneath with two white stripes on their brown backs, lay eggs in bark from May to August, depending on the geographical area.

To get the grubs, poke stiff but flexible wires up into the tunnels after pulling away the sod. Put several mothballs around the openings, wrap that section of the trunk, and seal with tape so the fumes will go into the holes.

A good prevention idea from A.P. Thompson, a well-known organic apple grower of Golden Acres Farm, Front Royal, Va., is a mixture of nine cups whitewash (hydrated lime, so don't get it on your skin) plus one cup bleached flour and one-half cup red pepper. Mix with water to the consistency of paint.

Paint the trunk from soil level to the place where limbs branch off. Keep a coat of this mixture on the trunk from March 1 to killing frost.

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, authors of several books on gardening, and greenhouse operators for more than 25 years.