WSU CAHNRS

Washington State University Extension

Garden Tips

Lavendar RSS feed

LAVENDER IN THE GARDEN

GARDEN TIPS – written by
Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA
published NOVEMBER 7, 2014

Are you a fan of lavender? I am. I like this garden perennial because it has pretty, delightfully fragrant flower spikes, it has attractive aromatic gray foliage, it attracts honeybees, and it has few pests.

Our region of Washington is well adapted to growing English lavender. This is not surprising since English lavender is native to the mountainous areas of the western Mediterranean region, not England.

English lavender grows best in full sun and well-drained soil that is slightly alkaline. It is considered drought tolerant once established and will suffer if the soil is kept too wet. Hardy to Zone 5, it will survive our cold winters and it performs extremely well under our hot summer conditions.

The species form of English lavender is considered an evergreen or semi-evergreen, woody shrub. It grows to a height of six feet and produces lavender (no surprise) flower spikes, sometimes twice a the season.

Plant breeders have worked to create many different English lavender cultivars (cultivated varieties) of varying sizes and flower color including deep purple, pink, and white. Hidcote with deep violet blue flowers is a popular cultivar that tops out at a height of 16 inches and Munstead with lavender blue flowers reaches a height of 18 inches. If diminutive is more to your liking, look for tiny Nana or Lavance that only grow10 inches tall.

Lavandin lavender (Lavandula x intermedia), often referred to as French lavender, is a sterile hybrid or cross between English lavender (Lavandula angustifolia ) and spike or Portugese lavender (Lavandula latifolia). Lavandin is less hardy and blooms only once a season, blooming later than English lavender. Because its seed is sterile, it is propagated by cuttings.

Containing more camphor, Lavandin lavender has a much stronger, pungent fragrance. It is favored in commercial production for use in cosmetics, soaps, and perfumes because it yields larger amounts of essential oil than English lavender. English lavender is usually preferred for culinary uses because of its milder, sweeter flavor.

There are also a number of different lavandin cultivars, most having lavender to violet blue flowers and not reaching a height of more than three feet. Provence and Grosso are cultivars used for lavender oil production in France.

Lavender should be pruned heavily every year starting when the plant is young to discourage growth from becoming woody and scraggly. If pruned properly, lavender shrubs can remain attractive and productive for 10 to 15 years or more.

Starting when the plants are one year old, prune the stems back by one third early in the season when new growth starts to emerge from the base. Flowers are formed on new growth so you will not be removing flowers if you prune early. You may also cut back green growth immediately after flowering.

Some experts advise pruning more severely every two to three years, pruning the plants back to a height of six to eight inches. However, if that means pruning to brown woody leafless stems, do not do it. This wood has few, if any, live buds capable of growing. If you have an older, woody lavender, try pruning the shrub back severely in the spring, but still leaving two to three inches of green productive growth on the ends.

If you do not have English lavender your garden, plant some next spring. Pruned properly, it is a great addition to any landscape or garde
Published: 11/7/2014 12:17 PM

OUT IN THE GARDEN – POWDERY MILDEW AND LAVENDER

written by Marianne C. Ophardt WSU Extension Faculty for the Tri-City Herald, Kennewick, WA I was out in the garden this week to ‘dead head’ or remove the spent blossoms from my roses. Conventional wisdom says you should prune off these dead flowers by carefully pruning back to a five-leaflet leaf. When you have a number of rose bushes, this gets to be a tedious, time consuming chore and many summers went undone in my garden. Last year, I decided to take an easier approach using a little electric rechargeable hedge trimmer. I now use it to quickly trim off the dead flowers from my roses and shrubby perennials. After using the hedge trimmer, the re-bloom on my roses late last summer was better than ever. However, I’m not sure how good it will be this year. While ‘buzzing’ off the dead blooms, I noticed that my roses have more powdery mildew than other years. Other local gardeners have also been noticing this problem on their roses too, as well as on other plants that are susceptible to powdery mildew, such as cherries, grapes and sycamores. Powdery mildew is a group of similar fungi that attack plants. The tell tale sign of powdery mildew infected plants is the grayish white ‘powdery’ coating on green leaves, stems, and fruit. Severe infections are very evident with a thick white coating but moderate to mild infections are less apparent. Infected tissues tend to become stunted and leaves are usually curled or distorted. Infected areas may turn brown to black later in the season. The skin of infected fruit, such as apples and grapes, becomes leathery or ‘russeted.’ Unlike many fungus diseases that attack plants, powdery mildew does not need wet conditions to spread and infect plants. The powdery mildews are favored by humid conditions when the days are warm and the nights are cool. Infections are most severe where plants are crowded and have poor air circulation. Infections are also worse in moist, shady areas of the garden or landscape. Powdery mildew primarily infects immature succulent growth, so susceptible plants that are watered and fertilized heavily are top candidates for infection. Knowing what conditions favor powdery mildew is a good guide to managing the disease. Not crowding plants and pruning to ‘open them up’ to allow for good air circulation can help. This year, I didn’t prune as many canes off my roses as usual and the shrubs are quite dense. Next year, I can lessen the mildew problem by leaving fewer canes when I prune in the spring. It’s also important not to create lush vegetative growth by applying too much water or fertilizer. In the fall, rake up and dispose of the fallen leaves from infected plants. During the winter, prune out and dispose of severely infected canes or branches. Surprisingly, another way to manage a powdery mildew infection is by thoroughly wetting the surfaces of leaves and stems of infected plants two or three times a week. This washes some spores off the plant and it also destroys other spores by causing them to burst. If possible, do this early in the day. The best way to avoid problems with powdery mildew is to plant resistant varieties. Certain varieties of plants are more susceptible to the disease than others. You are much further ahead to plant resistant varieties of roses, grapes, sycamore, and others. There are some fungicides that can be used for mildew control when an infection is severe and the other methods haven’t worked. However, these aren’t needed during the summer when higher temperatures usually hold it in check. If you feel you need a fungicide for control, apply it earlier in the season and follow label directions. Repeated applications usually will be needed to protect new growth as the plant grows. While checking out the garden, I also noticed that the lavender was just about done blooming. I adore lavender. You can’t go wrong with this shrubby perennial. It’s a member of the mint family and is native to the Mediterranean region. It prefers well-drained, slightly alkaline soil. It’s easy to grow. It needs little water once established, it likes the heat, and it has few insect pests. However, it must have full sun and good air circulation. There are at least 20 species of lavender, but the most commonly grown garden species is English lavender, Lavendula angustifolia. It’s a hardy shrubby perennial, growing from one to three feet in height. The leaves are typically narrow. There are many very nice purple cultivars (varieties) of English lavender, but there are also a few white and pink ones too. Some of the cultivars popular with gardeners are Hidcote, Munstead, and Twickel Purple. Irene Doyle is favored for its ability to flower twice during the season. Lady was a 1994 All-America Selection that can be planted from seed and flowers the first year. Some of the Lavandin lavenders (Lavendula x intermedia) are also popular. These are hybrids between English lavender (L. Angustifolia) and Spike lavender (L. latifolia), a tender type grown primarily for its essential oil. The plants and leaves of Lavandin cultivars tend to be larger than those of English lavender and have a more pungent fragrance. Grosso grows to five feet across when in flower. Two other popular Lavandin cultivars are Provence and Hidcote Giant. Of course, there are many more cultivars that intrigue gardeners who love lavender. While lavender is an easy care plant, a little light pruning improves its looks and performance. In early fall you will want to cut back the plants a bit, not so far as to cut into woody stems, leaving one or two inches of green. Then in the spring you prune heavier, cutting back the plant from 1/3 to 1/2 of its size, and still leaving several inches of green above the woody stems. This may seem drastic but it stimulates new growth and results in a denser, more compact ‘shrub.’ Seeing the lavender reminds me that this weekend is the annual Sequim Lavender Festival where lavender enthusiasts can visit beautiful lavender farms, buy lavender products from vendors, and take in the lovely sights and aromas of the ‘Lavender Capital of North America.’ They expect over 30,000 to attend. Whew! If you don’t like such big crowd, think about visiting our local lavender growers and buying their products. ‘Lavender’s R Us’ even holds a lavender festival in June in Dayton and encourages visits to their Waitsburg store. Some of the lavender growers in our region are: Lavender

s R Us, Robin Thomas, Waitsburg, WA 337-9020 Lavenderthyme, Susan Bunnell, Prosser WA, 973-2855 Blue Mountain Lavender Farm, Karen Grimaud, Touchet WA 529-3276

Published: 7/16/2005 11:45 AM

Archives

Categories

Garden Tips, WSU Extension, Benton County, 5600-E West Canal Drive, Kennewick, WA 99336-1387, 509-735-3551, Contact Us

WSU Extension, Franklin County, 1016 North 4th Ave, Pasco, WA 99301-3706, 509-545-3511, Contact Us
© 2017 Washington State University | Accessibility | Policies | Copyright | Log in