Washington State University Extension

Garden Tips

Archive for May 2011


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

I’m finally beginning to contemplate which colorful flowering annuals I want in my large patio pots this year. There will definitely be some of my favorite Wave petunias, but I don’ t like to get into a rut so I’ve been checking out some of the newest annuals on the market.

Last year was the first time I had success with calibrachoa, sometimes called mini-petunias or million bells. I had tried calibrachoas when they first arrived on the gardening scene but was not impressed with their performance. After last year’s success, I want to try more.

One exciting new calibrachoa is Calibrachoa ‘MiniFamous Double Pink evol.’ from Selecta First Class. This is the newest member of their MiniFamous Double series. It produces beautiful double pink 1 to 2-inch flowers in abundance. It’s easy to grow with a sem-trailing habit, reaching a height of 6 to 10 inches and a length of 2 feet. It’s very pretty with bright pink double flowers, but it’s also tough and should be able to tolerate our summer heat . No deadheading (removal of spent flowers) is needed to keep it blooming

Blackberry Punch is the newest member of the Proven Winners calibrachoa “Superbells” line. I wonder if “Superbells” got their name because they stay bushy even under the stress of summer heat or because they’re covered with blooms from early spring through fall? Blackberry Punch reaches a height of about 14 inches and a length of 36 inches. The flowers have a “blackberry” purple center that blends into the dark magenta petal edges. It doesn’t require deadheading. Coralberry Punch is another new member of the Superbells line. It has interesting dark throated intense coral colored flowers. Both are attractive to butterflies and hummingbirds.

Another plant I never had much success with in the past was lobelia. This pretty pot filler always faded out fast as soon as the summer heat came on. Last year I tried Proven Winners

Lucia Lavender Blush

lobelia and was surprised that this new easy-to-grow lobelia stayed covered with light lavender-pink flowers until late summer. It grows about 6 to 8 inches tall and trails to 24 inches long. It’s also attractive to butterflies and hummingbirds. There are two other series of heat tolerant lobelia, ‘Techno Heat’ from Fischer and ‘Waterfall’ from Ball Flora. These lobelia also make it through mid-summer without disappearing.

A new intriguing annual is Zinnia ‘Queen Red Lime.’ What makes this zinnia worthy of mention is its unique flower that had bright lime colored center petals that transition to mauve petals at the bloom’s outer edge. As a Zinnia elegans variety, the blooms are produced on well-branched plants that reach a height of 24 to 30 inches. Combine it in a container with the chartreuse Zinnia ‘Envy,’ purple fountain grass, and black (maroon) sweet potatoes for a showstopping planter.

Last but not least are Wave petunias. (I just couldn’t leave them out.) One of the newest is Shock Wave Coconut with 1.5 to 2 inch creamy white flowers. As one of the Shock Wave series, it has earlier, more weather resistant, and self-cleaning flowers. The plants reach a height of 8 to 10 inches and a spread of 2 to 3 feet. Another newer Shock Wave is Denim. It produces flowers that start out a deep-blue violet that gradually fade to a lighter stonewashed denim silvery lavender.

Spring has finally arrived. It’s time to check out the new flowers at your local garden store and get your planters started. Have fun!

Published: 5/21/2011 3:29 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Not long ago one of my sons noted that I was an optimist who tends to look on the bright side of things. Not always. Lately, I’ve been downright grumpy about our spring weather. Just when I think spring has arrived and it’s safe to plant tender annual flowers and vegetables, freezing nighttime temperatures loom in the forecast. Plus, there’s the wind. Even if frost doesn’t get your plants, the ever present wind can do just as much damage.

I’ve been trying to wait patiently, noting that the last average date of frost is between May 1 and May 15, but it’s an average. As I write this column, no frosty nights are predicted, but nighttime temperatures are still below 50 degrees. That’s pretty chilly for warm-season plants. The curmudgeon in me worries that it may not be truly safe to plant until late in May.

On the positive side, I’ve had more time to look around the yard and tend to other plants. Earlier inspections revealed significant dieback on some shrubs due to winter injury. I pruned them sparingly and have been waiting to see the complete extent of the injury. The latest examination of my roses and a few other shrubs revealed additional dead wood that should be pruned out. The good news is that a few shrubs that I thought had succumbed are sprouting at the base. I can feel some of my optimism returning.

I’m certainly not the only local gardener to lose plants from winter injury. I talked about winter burn damage earlier in the season, but now entire plants are suddenly turning brown. A number of cedars in local landscapes seem particularly hard hit. That’s not surprising, as some cedars aren’t extremely cold hardy.

Deodar or Himalayan cedar (Cedrus deodara) and blue atlas cedar (Cedrus atlantica f. glauca) are prone to injury from cold winter temperatures. The blue atlas cedar is supposedly hardy in Zone 6 which includes most of our local region and should be able to endure temperatures down to -10 degrees. However, it’s fairly common for atlas cedar to be injured by sub zero temperatures only down to -5 degrees. The Deodar cedar is more tender, rated for Zones 7-9 where temperatures don’t go below zero.

Both these cedars will suffer damage from severe cold temperatures, but why hasn’t this damage shown up after other recent winters when we experienced temperatures just as cold as this past year? Timing is the most likely factor. Our first period of severely cold weather happened abruptly after relatively mild late fall weather. The cedars and other landscape plants with significant dieback, were subjected to injury because they weren’t completely physiologically ready or “acclimated” for the extreme cold temperatures more typically experienced in mid-winter, not in late fall.

Other factors involved in cold temperature damage involve the severity of the temperatures, the length of the cold spell, the health of the plant, the occurrence of fluctuations between mild and cold weather, the plant’s location, and the genetically determined winter hardiness of the plant.

Signs of cold temperature injury will most likely continue to keep showing up over the next couple of months, especially when hot weather arrives and puts additional demands on the injured plants. On the bright side, the loss of a tree, shrub, or perennial here gives you a chance to try something new. I guess I am an optimist after all!

Published: 5/7/2011 3:19 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

Spring is here! What a difference some warm weather and sunny days makes. While it’s still prudent to keep an eye on the weather forecast, now is finally the time to get busy out in the garden.


In the vegetable garden, it looks like the danger of frost is past. If you have transplants you’ve been wanting to get planted, you can get started. Don’t forget about “hardening” those transplants if they’ve been sitting in the house or garage a while. Sudden exposure to full sun and wind can damage plants and delay their growth and production.

You can harden your transplants by putting them outside in a sheltered location where they’ll get two to three hours of direct sun and be protected from harsh wind. Over the next week, gradually increase the time exposed to direct sun and decrease their watering, but don’ allow them to wilt.

If you purchase your transplants from a nursery where they’ve already been exposed to sun, cool temperatures, and wind, you don’t need to harden them before planting. However, avoid purchasing older, larger transplants. They’re slower to resume growth after transplanting and end up being less productive than younger, smaller transplants. Look for healthy, medium-size, stocky, dark green plants that aren’t already flowering.

The air temperatures have finally warmed up for us, but the soil is still cool. I would wait another week or more to plant seeds for crops of melon, squash, and cucumbers. They need soil temperatures of 70 to 75 degrees for good germination.


If you haven’t already fertilized your lawn for the first time this year, now is a good time.

With warmer weather, lawn irrigation for the season has started. Check for even coverage using straight sided soup cans. Place the cans uniformly throughout the zone you’re checking, staying within a foot of the perimeter and at least two feet away from spray nozzles. Next run your regular cycle for that zone. After the cycle is complete, compare the depths of water in the cans.

If the depths vary widely, try to determine the reason. It could be poor design, but the cause could simply be an obstacle, such as a tree branch or tall ornamental grass that’s stopping the water stream, or you may need to adjust the flow of some sprinkler heads or replace worn ones. More even distribution can help you save water.


It’s always a good idea to check your drip irrigation system each spring, especially if you didn’t drain or blow out your system in the fall. You may have cracked lines or clogged emitters. Experts recommend flushing your mainline before you start your drip in the spring along with cleaning the filter to remove any dirt. After flushing, cap the system and turn the water on to check the emitters. If they aren’t operating correctly, either unclog or replace them if needed. Many of your plants on drip have probably grown. Consider if you need to add more emitters to provide them with enough water.

Drip irrigation is a great way to conserve water and to reduce weeds in your garden. Do you want to learn more about drip irrigation? A super new on-line publication is available from WSU Publications, “Drip Irrigation for the Yard and Garden” by Dr. Troy Peters, WSU Irrigation Specialist. This free publication discusses how to set up a drip irrigation system for a small yard or garden space. You can find it at:

Published: 5/14/2011 2:31 PM


written by

Marianne C. Ophardt

WSU Extension Faculty

for the Tri-City Herald, Kennewick, WA

I’ve never been a big fan of most spring flowering trees. They may be lovely, but their bloom is so ephemeral. I tend to be drawn to other characteristics that last longer, such as bark texture and branching form. However, don’t get me wrong, I do enjoy spring blossoms that announce the long awaited end of winter. For me, daffodils, tulips, and spring flowering shrubs are a must for any landscape.

A once popular spring flowering shrub is flowering quince (Chaenomeles japonica). This shrub is a bright spot in spring with its reddish-orange flowers. It’s easy to grow and can tolerate some difficult conditions. The species grows to a height of 10 feet with a rounded form, but its cultivars tend to be shorter and pruning can keep larger forms in check.

In late fall, flowering quince frequently develops apple-like fruit that are quite aromatic when they ripen in late fall. This shrub may be pretty when it blooms, but its popularity has waned because it’s not gardener friendly. Armed with woody spines, it has a tendency to fight back when pruned and it catches blowing leaves and trash.

The rather large size and thorns of flowering quince definitely put it on the not-so popular list of today’s gardeners. However, plant breeders have come to the rescue. New on the garden scene are three new flowering quince being marketed by Proven Winners in their line of Color Choice Flowering Shrubs.

These new quince are called Double Take Pink Storm, Double Take Scarlet Storm, and Double Take Orange Storm. The name perhaps refers to their beautiful bright double flowers or it may mean you’ll do a “double take” when you see the camellia-like flowers produced in early spring. These new flowering quince only reach a height and width of about 4 feet, much more restrained than previous cultivars. They’re also thornless, fruitless, hardy, and drought tolerant once established. What’s not to like? The Double Take series will be available on a limited basis this year and more readily available from nurseries next year. I can’t wait to plant a Double Take Pink Storm in my front landscape bed.

Bangle is another Proven Winners Color Choice Flowering Shrub. It’s a woadwaxen, also known as Lydia broom or Dyers greenwood, but we’ll just call it Genista. Genista looks a lot like the Scotch broom (Cytisus scoparius) that has become a noxious weed throughout the Pacific Northwest, especially west of the Cascades. It’s a problem because it crowds out native vegetation, taking over grasslands and open forest land, plus it’s seeds are toxic to livestock and horses.

Bangle is a cultivar of Genista lydia and it’s not invasive like its nasty cousin, Scotch broom. Bangle was named one of the “Best New Trees and Shrubs of 2008

by Better Homes and Gardens. This new shrub is covered with bright yellow flowers in spring to early summer. It only reaches a height of two feet and has a mounded habit. In addition to being very showy when in bloom, it’s a hardy, low maintenance shrub that’s heat and drought tolerant once established.

Check out these and other spring flowering shrubs to announce the end of winter and brighten your spring landscape.

Published: 4/30/2011 2:19 PM



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