Q: My 2-year-old clematis grew beautifully and started to bloom. Then suddenly 95 percent of its leaves turned black. This has happened two years.A: This sounds like clematis wilt, the name for a problem whose exact causes are not fully understood. Suddenly all or just one stem of a clematis will wilt - looking as if it had been deprived of water for too long.The widest-held assumption is that clematis wilt is a fungal problem. It appears to affect spring-blooming hybrid clematis (the stunning, large-flowered types) and not species. The affected portions of the clematis should be pruned out and placed in the trash (not compost).Topsin, a chemical fungicide, is frequently recommended, with two or three applications at seven- to 10-day intervals. Since you have a recurring problem you should consider moving the clematis to another location and applying the fungicide as a prophylactic in the spring, when the new growth resulting from late-winter pruning is, say, two or three feet long.The good news is that, properly planted, a clematis affected by wilt will survive. But proper planting for clematis is different from almost every other garden ornamental. When planting, place the clematis deep enough that two leaf nodes - the points on the stem where leaves appear - are beneath the soil when you are finished. The clematis will develop roots at the nodes and become well anchored. As always, clematis prefer nonacid soil and a cool root zone, but full sun on the top growth. The cool-sun combo can be accomplished by planting just behind (the north side of) a shrub or bushy perennial or by rigging some shade for the root zone.---

Q: We have two American yellowwoods that we planted in the fall of 2001. The next June, we had minor flowering and since then nothing, with the exception of one small chain last month. I've learned that they don't necessarily bloom each year, but I think our experience has been especially unfortunate. I fertilized both trees each spring using Miracle-Gro spikes.A: Patience is called for - but worth it. A yellowwood (Cladrastis kentuckea) in my neighborhood was planted in the early to mid-1990s. It is now truly a tree - 25 feet tall, 25-foot spread, on its way to twice that - but only in the last three years has it bloomed enough for people to really notice it.Miracle-Gro tree spikes are listed as 15-5-10 on the nitrogen-phosphorus-potassium scale. Nitrogen promotes foliar and root growth, which is good for a young tree. Among perennials and shrubs, excess nitrogen inhibits blossoming, but I think your yellowwoods are simply young, not over-nitrogenized.Send your gardening questions to Michael Martin Mills, The Philadelphia Inquirer, Box 8263, Philadelphia, PA 19101, or send e-mail to: Millsmphillynews.com. Please include name and locale.By KRT News Service