Late Spring Answers on Tulips and Training, Butterflies and Begonias

Washington's growing season is in full swing.

Q My wife loves tulips. Is it true they only last one to two seasons? Are there any species that come back every year? -- Gary S.

ATulips have a well-earned reputation of not returning for more than a year or two in this region because they will decay when their bulbs are left in the ground all summer. Some varieties, however, can better tolerate heavy soil and humidity. Drainage is the most important soil condition; you may even need to create a gravelly growth medium.

Several species to look for are the starry-flowered Tulipa tarda, white-and-gold; T. turkestanica, cream-and-yellow; T. batalinii Bright Gem, canary yellow; and T. praestans Fusilier, scarlet. They grow only six inches tall but make a good edging plant for early spring color. Plant in the fall.

Following your advice, I've had excellent results with Messenger on roses and phlox. Will it work on azalea petal blight? -- Bob B.

Messenger, an immune-system enhancer for plants, is labeled for petal blight and, through chemicals called harpins, will help your azaleas heal themselves. Apply monthly, beginning now, in the morning. Vegetation responds best if actively growing when you treat. Follow all labeled instructions.

For 15 years, my front yard has been overtaken by cicada-eating bees. I know they are beneficial, but what can I do to get rid of them? -- Jeanne M.

Cicada-killer wasps tend to be transient and move on in a few years. Because the insects have taken up residence for so long, they could be mining bees or digger bees. Neither mining bees nor cicada-killer wasps are aggressive.

Unlike the honeybee, mining bees are solitary. But large numbers of them may nest near one another if soil conditions are suitable. You should not treat mining bees because they are extremely beneficial insects of considerable importance in the pollination of many types of plants.

If you do have cicada-killer wasps, you can sprinkle Sevin (active ingredient carbaryl) around the holes in the evening, following label directions. This should kill them, though the process will take more than one season.

I never learned the basics of gardening, and I recently bought a house with a big yard and garden. Do you know of gardening classes in the D.C. area for novices? -- Bea

Check out basic horticulture courses or landscape-design classes at Montgomery College; Northern Virginia Community College; Prince George's County Community College; the University of Maryland; George Washington University Center for Continuing Education; the U.S. Department of Agriculture Graduate School; the county Master Gardener Programs; and through the Cooperative Extension System in Maryland, Virginia and the District. You can also contact local gardens to get on mailing or e-mail lists to receive information about their educational programs.