Garden Detective: Pruning, propagating a yucca

DEAR JESSICA: I have a 5-year-old yucca houseplant that has grown to the ceiling, but only the top 18 inches have green leaves. (Other canes appear to be dead.) Can you offer suggestions to get it to a manageable height? If I cut it down, will the original plant produce new growth? How would I cut it, and can I regrow the cuttings? --Suzanne Surdo, Deer Park

DEAR SUZANNE: Yes, you absolutely can shorten the height of your yucca. Simply saw the canes or use loppers to bring them to the height you desire. Best not to cut more than half, however. New leaves will grow from the cut. You also can cut the canes you believe are dead at soil level. If they're not really dead, they'll regrow.

If you want to propagate more plants, don't discard the removed portion of the canes. Just replant them, cut-side-down in potting mix and cut off the leaf portion at the top. Water. New roots will grow, and leaves will follow.

DEAR JESSICA: I have two huge peony plants. My problem is they are covered in tiny ants so I can't cut them and bring them into my home. Is there a way to get rid of the ants? How can I prevent this next year? --Doreen M. Jones, Kings Park

DEAR DOREEN: Immature peony buds secrete a sweet, sticky sap that attracts ants. There's really no way around that. The good news is that once the buds open, the sap is gone and so are the ants. If you want to cut them for indoor display, do so when they are still in bud. Take care to time this correctly: Cut too early, and the buds might not open. Wait too long and ants may be trapped between opening petals and brought inside. The buds should have a bit of color and have the softness of a marshmallow. Shake or wipe the ants off outdoors, then bring inside for a pest-free display.

DEAR JESSICA: I have three lilac bushes that were started from offshoots of a mature lilac bush three years ago. I planted them in three different locations: one facing southwest, one facing south with the roof drain near it and a third facing north. None have bloomed or even had buds yet. All appear healthy and are growing well. -- Mary S., via email

DEAR MARY: As you know, new lilac plants can be started easily by digging up shoots that grow at the base of the mother plant and replanting them elsewhere. Making new plants this way, however, takes patience: It can take several years for them to become mature enough to bud and bloom. Hang in there.

DEAR JESSICA: We had various colors of irises. I moved them last year. When they bloomed this year they were all white! Is there something that would cause this to happen? --Kathleen Jokubiel, Deer Park

DEAR KATHLEEN: That certainly is odd, but not unheard of. I can't be sure what is going on, but perhaps, armed with some clues, you can do your own sleuthing. I'll start with the most likely and move on from there.

White irises typically are stronger than colored ones, and when planted in a bed with other-colored irises, they may choke them out. It's possible your colored irises simply were out-competed, leaving you with a bed of white and the impression that the colored ones have changed.

Irises produce seeds, which drop into the soil and grow into new plants if left undisturbed. The irises that grow from these seeds are not always the same as their parents, so it's also possible you moved some newer seedlings. Or maybe they had already choked out the colored irises when you moved the bunch, but you didn't notice because they weren't in bloom at the time.

You say the original bed contained "various colors of irises." Is it possible you only dug up and relocated the white ones?

Tomato Challenge

After Joyce and John Chanda lost their Massapequa home during superstorm Sandy, the couple relocated to an apartment in Holbrook. John and their son, Justin, have always had "an obsession with gardening, especially, tomatoes," Joyce said, but after leaving their garden behind, "we thought this enjoyment was over."

But the family wouldn't give up its love of gardening: The Chandas forged a small 4-foot-square tomato garden behind their new apartment, and Justin, who now lives in a fourth-floor apartment in Brooklyn, grows tomatoes on the roof. The take-away? "You can fulfill your passion and attain joy with a little hard work and imagination," Joyce said. We're looking forward to meeting the Chandas at this year's Great Long Island Tomato Challenge.

Are you in? This year's contest will be held at 7 p.m. Aug. 23 at Newsday headquarters (235 Pinelawn Rd., Melville). Bring your biggest, heaviest, ripe homegrown tomato, and Garden Detective Jessica Damiano will weigh it and crown the 2013 Tomato King or Queen.

In the meantime, send a photo of yourself with your tomato plants, along with details about your growing strategy, to jessica.damiano@newsday.com.