I have a garden bed that falls in a funny spot. There is a sidewalk that runs north-south between the house and garage with small beds on either side. The area gets shade in early morning and evening but full sun in the middle of the day.
On the garage side I have black-eyed Susans, red hot pokers and coreopsis plus lots of marigolds, so red, orange and yellow are the colors I am looking for. I have not yet found the right plants for the house side. I am leaning toward mostly annual since I like the idea of having an area that can be different each year. But I'll probably put in a few perennials.
Here's the catch. The dryer vent blows right in the middle of this bed. So far, powdery mildew has been an issue, more on the house side than the garage side. I assume this is from the weekly blast of warm moist air into an area that is sort of enclosed.
I see four minor and one major problem to be solved.
First is sunlight. You say your garden gets sun in the middle of the day and so you're growing species that need full sun. Yet to a plant, full sun is a matter of duration. A sun-loving plant needs light that's strong enough to cast a sharp shadow for at least 6 hours a day.
In less light, a sun-lover won't thrive. It may survive but won't be as sturdy, floriferous or healthy as it could be. Any problem its species can experience, such as a tendency to mildew, will probably develop in a plant that is not receiving its minimum daily sun requirement.
I doubt that your beds receive six hours of sun each day. One day in spring, watch and tally the sunlit hours there. Or in summer, compare a flowering stalk from one of your marigolds or black-eyed Susans to one grown in a bed open to the sun all day. If the sunny hours or your plants don't measure up, switch to half-sun plants.
The second problem is heat. It will be worst along the wall that faces west. Plants there must cope with sudden change from cool morning shade to full sun and a day's greatest heat. Such plants are few and far between. Look for half-sun species with good heat tolerance such as bigroot perennial geranium (G. macrorrhizum) and annual periwinkle (Catharanthus roseus). Your color scheme may have to change!
The third problem is air circulation. Walls blocking the prevailing winds. Where air can't move freely, fungi such as powdery mildew get the upper hand. Avoid planting mildew-prone species and varieties, thin the stems of perennials each spring, and allow ample space between annuals.
Finally there's the the dryer vent. I don't know any plants that thrive on air so hot, even if it comes only once a week. Don't plant near the vent. Place a non-plant item there, such as a sculpture or twig screen. It will catch the eye and act as a baffle between plants and the hot blast.
Underlying these four minor problems is a basic gardening issue. We should assess a site, see what it can provide, then plant species that can grow well there, arranged in ways to help their growth. Alternatively, we can imagine a particular garden -- a full sun, annual flower display, for instance -- and then seek a site that will meet those plants' needs.
You've taken the second route, but gone off track in trying to force the garden into a site it can't match. If you begin again by embracing the site characteristics and considering only plants that will thrive there, you may not end up with orange, red and yellow annuals. However, you will find better, if fundamentally different, possibilities.
I enjoy answering questions you mail to me or post on my school's website. However, some problems have no solution. Don't expect much help from me if you pose a "stumper" such as:
Why is it that the species I most want to grow are those that cannot survive in my garden or climate?
to humor in the garden. Plan a high court for the veggie bed, with Green Goddess eggplant, Siam Queen basil and Red Emperor beans. Or expand a catmint and lambs ear planting into a full menagerie with horseradish, horehound and a bit of fleabane for good measure.
to depending on anything to be the same this year as last. Be thrilled over different bloom combinations. Enjoy old stars in unexpected supporting roles and applaud new divas as they take the spotlight.
Originally published 1/8/05