Friday, June 18, 2010

Smoke Trees



Smoke trees (Cotinus coggygria) are wonderful additions to small, urban gardens. They may eventually reach 25' in height, but can be pruned to stay much smaller. Typically, they are multi-stemmed, but can be trained to have a single trunk, as this one has.

Smoke trees come in both green and purple-leafed forms, but the purple seems most popular here in Seattle. Some cultivars have purple leaves in spring that gradually turn green over the summer. If you want plants that hold their purple color until fall, choose varieties like: 'Royal Purple' and 'Velvet Cloak.'

They are called "smoke" trees because as their flowers fade, they take on a fuzzy appearance that looks like puffs of smoke.
Here you can see a closeup of the tiny, yellow-green flowers and those gorgeous purple leaves. Later in summer, these flowers will take on that characteristic "smoky" look.

In addition to the dramatic flower display, smoke trees have stunning red-orange fall color. They are also drought tolerant, once established. They thrive in poor, rocky soil. And they come in colors other than purple, which you can read about in this post, More Smoke Trees.


Tuesday, June 15, 2010

Keeping the Bloom on Your Roses


I've been noticing that the roses in West Seattle gardens are particularly beautiful this year. This is worth noting because the climate in the Pacific Northwest is not the best for growing roses. Roses love sun and we don't get a lot of it. Our cool, damp days are better suited to the growth of fungal diseases, like black spot, that love to build colonies on the leaves of our rose plants. 
(Some roses more suited to our climate than others. If you want to know more about them, I recommend Christine Allen's book, "Roses for the Pacific Northwest.")
So why are our roses looking so good this year? I suspect that it has to do with the extra rainfall we've had this year. Our usual rainfall pattern is that we have adequate rain to keep gardens looking lush through the month of May. In June, we often have a lot of cloudy days, but not very much rain. Gardeners are fooled by the cloudiness into thinking the garden is getting enough water, when that isn't necessarily the case. Particularly with roses, which are greedy on all fronts: they want lots of water, sun, and nutrients. 
So far this year, we have had three times the usual amount of rainfall for the month of June. This has had the effect of extending bloom time for lots of spring flowering shrubs and perennials. Roses, most of which are at the beginning of their bloom season, are getting off to a healthy, well-watered start this year. If you want to keep the bloom on your roses throughout the summer, I suggest that you consider following up with a good fertilizing routine. Ideally, that routine would have started months ago, but whatever you do to feed your roses from here on out will be rewarded.
Here is a 4-Step feeding program for roses that was given to me years ago by a rosarian with a passion for both beautiful roses and keeping hazardous chemical use to a minimum. He has long since sold his nursery and moved out of the area. Thanks, Robert, wherever you are! 
If you are fertilizing your plants for the first time in June, skip step one and continue from there.

  1. In February, March or April, apply 1 cup of superphosphate to each rose in your garden. Superphosphate works better than bone meal because it breaks down faster. It builds strong root systems and improves the rose's ability to flower repeatedly over the summer. It also costs less. Use it only once a year.
  2. Apply 1 cup of alfalfa meal of 2 cups of alfalfa pellets to each rose in March or April. Some rosarians repeat this application in June. Alfalfa releases nitrogen slowly and releases an enzyme that dramatically increases the rose's feeder root system. This means that the plant can make better use of available nutrients in the soil, as well as the fertilizers you give it.
  3. Starting in April, as the soil begins to warm, apply 1/2 cup of granular 16-16-16 fertilizer, and re-apply every 4-6 weeks. Your last application should be in August. (As with all granular fertilizers, water well after application unless you have adequate rainfall to dissolve them.) This step is the core of your feeding program.
  4. Apply Epsom salts (magnesium sulphate) to your roses to stimulate new, larger canes and to enhance flower color. Use 3/8 to 1/2 cup per rose in May or June. Magnesium sulphate, combined with a complete feeding program, does a good job of rejuvenating old, tired roses. 
Along with a good feeding program, be sure that your roses get plenty of water during dry spells. They aren't as thirsty as lawns, but still - they aren't drought tolerant. Also, roses need lots of sun. There are a few, rare cultivars that will grow in shade, but most will be leggy, buggy and fail to bloom unless they are in full sun.

Be aware that even under the best circumstances, there are some rose varieties that are hopelessly susceptible to problems. If you have them in your garden, you might be better off replacing them with hardier cultivars. Ask at West Seattle Nursery for suggestions. There are lots to choose from. Enjoy!
Do you need a Horticultural House Call? For more information or to make an appointment, please email me.