Helping a rhodie that's reluctant to bud, encouraging delphinium to bloom

Q: I have a 'Bergie Larsen' rhododendron that won't set buds. Any tips?

A: The most likely culprits are too much nitrogen fertilizer or too-late pruning. Nitrogen fertilizer pushes rhodies to produce more foliage than flower. Since rhododendron flower buds form in late summer, the shrub should always be pruned shortly after blooming to avoid injuring next year's buds.

The solution to the first problem is to avoid nitrogen-rich fertilizers. Transplanting or root pruning are two ways to encourage your rhodie to set buds and stop putting so much of its energy into leaves. Phosphorous and potassium-rich fertilizers promote bud formation, especially when applied in autumn; be sure to look for fertilizers for rhododendrons.

If your rhododendron is new, it may delay producing buds for a year, which sometimes happens when plants transition from a cosseted nursery environment to the reality of the garden. Cold, wet winters and heavy clay soil can also discourage rhododendrons from setting buds. Make sure that your rhododendron is growing in conditions that suit it best; 'Bergie Larsen' is a woodland rhododendron that can take only partial sun and prefers shade.

When your rhododendron begins to bloom, you can stimulate plentiful bud production by deadheading flowers shortly after they wilt.

Q: Last summer, the delphinium in my garden didn't bloom as well as they did in the past. Should I pinch them back now that they're coming up or divide the clump?

A: According to Log House Plants, an Oregon wholesale grower of gorgeous delphinium, these perennials need thinning every spring. When delphinium are about 3 inches high, select the strongest shoots, and cut all the others off at ground level. For older plants, keep about five shoots; for second-year plants three shoots; and just keep one shoot when you plant new delphinium. Such thinning helps delphinium grow strong and healthy with sturdy blooms. To learn how to propagate new plants from these cuttings, check out Log House Plants' Web site, www.loghouseplants.com.

Q: What is cut-and-come-again lettuce? I had a delicious salad at a neighbor's house, and she said it was made of cut-and-come-again. I can't find any seeds or starts of it.

A: Growing cut-and-come-again lettuce is more of a technique than a type of lettuce. With this technique, you harvest the tender young lettuce leaves frequently, before heads form. Begin by planting a blend of leaf lettuces in the ground, raised beds or in containers. Spread the seed very close together, not more than ½ inch apart, and cover it with fine soil or potting mix. Water and keep the soil moist until the seeds are established. When the plants have grown 4-5 inches tall, it's time to harvest by using sharp scissors to clip the leaves down to an inch tall. The lettuce will sprout back to be harvested again several times. Baby mesclun seed mixes work well, or some seed companies, such as Nichols Garden Nursery (800-422-3985; www.nicholsgardennursery.com), sell lettuce mixes labeled specifically cut-and-come-again.

Valerie Easton also writes about Plant Life in Sunday's Pacific Northwest Magazine. Write to her at P.O. Box 70, Seattle, WA 98111 or e-mail planttalk@seattletimes.com with your questions. Sorry, no personal replies.