Q. Mike: Our three lilacs aresix years old and had a total of three flowering "bunches" this year,which is typical of just about every year. They are almost six feettall and healthy (very green and lots of new growth), and get at leastsix hours of sun per day (more in the middle of summer). Can you pleasehelp—before I rip them out of the ground and feed them to the compostpile?! Thank You!!
---Jamie inRosman, N.C.
A. Lack of sun is the mostcommon reason for badly bloominglilacs. "Six hours" may seem like a lot, but it's pretty close tothe minimum necessary to get those huge sprays of flowers you're hopingfor. And how can your plants get MORE sun in the summer?! Generally,that's when leafed-out trees turn full sun into deep shade, not theother way around. Anyway, with lilacs, the more sun the more blooms;maybe you can prune back a few other plants to let even more raysthrough.
Lilacs are notorious for sulking for years after planting—so don'texpect blooms right away, new lilac owners! But six years is plentylong to get over it, and you say you do get pitiful little displaysevery year, so it could be overfeeding—which produces big plants withlots of growth but few flowers. If you're using chemical fertilizers,stop and sin no more; an inch of composta year will provide the naturally rich soil they crave.
Prune off those few flowers right after they fade; then don't prune theplants again till next year. Pruning from June on risks cutting offbuds, which of course, reduces flowering. Keep the plants well-wateredduring droughts; lack of summer water can cause the flower buds thatare forming to dry out. And finally, lilacs bloom best in coldclimates; your mild NC winters may simply be limiting your display (butmaking the rest of your life a LOT easier!).
Q. My rhododendron has largebuds that never open. The plant gets full southern sun and the soil israther clayish, but we try to augment with fertilizer. My spouse alsolikes to add topsoil to the base of the plant for some reason. Theplant has been in this location for seven years. Why doesn't it bloom?
---Heidi fromGreen Brook, NJ
Q. I have a compactRhododendron on the south facing side of my house. In the spring, itsblossoms start out a rich, light pink, but after several days they turnwhite. Why? And only a small percentage of the buds produce flowers. Ihave examined the non-blooming buds and they look brown inside with nosign of insects. The soil is fortified with peat moss and liquidfertilizer throughout the season. The surrounding mature trees provideshade all summer long, with about two hours of sun maximum once theirleaves are out. Do you have any suggestions that will enhance theappearance of this plant?
---Dr. Fred inElkton MD
A. "Full Southern sun?" Yow!You New Joisey-ites are lucky your darn plant is still ALIVE, much lessblooming. Rhodies are "under story" plants in the wild; as Dr. Fredseems to know, they thrive in the summertime shade of deciduous trees.I'm surprised the Red Cross hasn't come by to charge you with PlantCrimes for baking the poor thing—it needs shade! It also needs yourhusband to stop with the fertilizer and "topsoil" and to mulch withpeat moss and compost to provide the NATURALLY-rich (not chemicallyenhanced) soil rhododendrons crave. It also needs some shade so thosebuds don't bake dead in the summertime; did I mention that?
Dr. Fred: Your flowers start out pink and open to white because that'swhat color they are. Rhododendronflowers come in virtually every color of the rainbow; and severalvarieties behave exactly the way you describe, including "King George"and "White Pearl". If it's really compact, I'll bet it's "Loder'sWhite".
You also need to replace those chemical feedings with compost. And I'ma little concerned that your South-facing buds may also be cooking abit after those protective leaves drop, but it's more likely that youjust need to have a heavier hand with the water during dry times.Rhododendrons are THIRSTY plants that should be first in line for thehose when we go a week without rain; otherwise the flower buds dryout.
Q. I am baffled by twoquestions, and am hoping you know the answers. (1) When do I fertilizemy dogwood trees? And (2) Why did some bloom and others not, eventhough I planted them at the same time? (They all bloomed last year.)Thanks a million,
---Geri inStafford, Va.
If you're talking about chemical fertilizers, how about 'never'? Is'never' good for you? Chemical fertilizers are one of the biggestreasons for lack of bloom on dogwoods. So wake up and smell thecompost, Ger! And then give some to your trees—some peat moss too;because like many Spring blooming beauties, dogwoods thrive in anaturally rich, acidic soil. (It also takes dogwoods a REALLY long timeto flower—so again, be patient new owners; it will be at least fiveyears before you can expect a new tree to bloom.)
After that it gets tricky. Dogwoodsbloom best in full sun, but the tree itself prefers afternoon shade inwarmer climes, for which your Virginia certainly qualifies. Dogwoodsthat grow in full sun in your zone MUST be watered during dry times toprevent stress to the tree.
My best guess for your "Bizarro Boom" is that some of your trees gotmore sun and/or water than others last summer. Or, if they're not allthe same variety, some might be the type of dogwood that only bloomsevery OTHER year. Or….
You Bet Your Garden Question of the Week ©2006Mike McGrath
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