Your gardening questions answered

By Kathy Hatfield
Gardening Columnist

Back to Gardening Articles List

It's always fun to learn about other gardeners' experiences by fielding questions that come up during the growing season. Hopefully you'll find that these questions and answers will add useful information to your gardening knowledge.

Q: I have two heirloom rose bushes that bloom prolifically in June and look kind of ragged in July. Should these be deadheaded to encourage another bloom period?

A: It's not necessary to deadhead (cut off old flowers) roses that bloom only once, but the plants can be pruned. Because they bloom on the previous year's growth, they should be pruned right after they are finished blooming. Don't wait until fall or winter to prune them or you may drastically decrease the number of blossoms the following year.

Repeat-blooming roses benefit from deadheading to encourage them to continue blooming. After flowering, the production of rose hips (the fruit, or part of the plant that contains seeds) signals to the plant that its work for the season is done and it can stop producing flowers. Deadheading not only improves the appearance of the plant, but also prevents the formation of rose hips and encourages the growth of new flowers.

Around the beginning of September, it's a good idea to stop deadheading and let the last flowers produce hips, so that the plant becomes more frost hardy. Chemical changes within the plant focus the plant's efforts on preparing for winter dormancy by slowing growth and hardening the canes.

Q: Is there a culinary distinction between rosemary that grows upright and creeping rosemary? Can either of them overwinter outdoors?

A: Most rosemary plants have culinary uses, but the flavor and fragrance can vary considerably from one plant to another. The leaves are used as a seasoning and the flowers are edible for salads or as a garnish. Rosemary is a good choice for northern Colorado gardens, tolerating our poor alkaline soils, but not all are hardy here. Typically, the upright varieties are hardier than the prostrate ones, which may only tolerate temperatures down to 20 degrees F. Two cold-hardy varieties are 'Arp,' one of the hardiest, and 'Albus,' an almost shrubby type with white flowers. But even the hardier varieties may not be tolerant of temperatures less than -10 degrees F. Rosemary does not like wet feet in winter and needs to be protected from winter winds. More tender varieties can be grown as annuals or wintered indoors.

Q: I love the smell and taste of thyme, but it is so difficult to deal with those little leaves. Do you have any tips to make cooking with thyme easier?

A : Harvest thyme just before the flowers open. Cut off the top of the plant, leaving about 2 inches above the ground. It will continue to grow, but avoid harvesting a second time, as this will weaken its winter hardiness. I usually remove the leaves from the stem by running my thumb and forefinger down the stem from top to bottom. This is even easier if you dry the thyme before using it. Lay the fresh thyme on a screen or newspaper and let it dry in the shade. Dried thyme stores well in an airtight glass container.

Q: When I've purchased plants that are supposed to be drought-tolerant, the label usually says to water well until established. How long does it take to establish the plant before I can cut back on watering?

A: Factors determining how long it takes for a plant to become established are the type and size of plant, when and where it is planted, and the weather. The use of root-stimulating or transplanting hormones can hasten root formation. I have found that it usually takes one season of regular, deep watering of a drought-tolerant perennial to become sufficiently deep-rooted so that it requires little, if any, watering its second season.

Q: There is an unidentified plant in my garden with pink flowers (see photo). When I cut the blossoms off, the stem excretes a very white, very sticky juice. Should I pull it out?

A: The plant in question is common milkweed (Asclepias syriaca). Some people like to keep the plant in the garden because it provides nectar for many insects and is a host plant to several butterfly species. It also has interesting seedpods for dried bouquets. The seeds within are wind-dispersed and will provide numerous new plants without any help. If you don't want additional plants, don't let it go to seed!

Send your gardening questions to ocwildflowers@frii.com.