Q: My vegetable garden will be located against the south side of our house. It has full, hot sun in the summer. We are having a drip system installed. Since this is my first attempt at growing vegetables, what types of vegetables, herbs, tubers can be grown in this location? — Washington County, Oregon
A: You’re fortunate to have a space with a southern exposure, as most vegetables need at least six hours of direct sunlight per day, with more being better. It’s a good idea to spend some time observing your location to see exactly how much direct sun it gets when deciding what you want to grow. Take into account shade cast by fences, buildings and trees as the day progresses. Note, too, whether your spot is subject to strong winds, as that will need to be addressed if you are growing vegetables.
Washington County, Oregon, has a 150-to-250-day season for gardening (similar to Seattle’s) so you’ll have the best chance of success if you look for varieties of vegetables that can be planted, grown and harvested within that window. If your beds will be right up against a south-facing wall, you may be able to stretch the season a bit, especially if you use row covers or cloches to warm things up earlier. Since it’s your first year gardening, though, you might want to stick mostly to varieties that mature quicker to make sure you get something in return for all your work.
Tomatoes, eggplants and peppers grow well in hot locations, but make sure that the specific variety you choose doesn’t take longer to reach maturity than your seasonal window. There are many cultivars that will do well for you, especially those with smaller fruit. You still have time to start tomatoes from seed indoors, or you can wait until late spring/early summer and buy starts to transplant into your garden.
Cucurbits, like cucumbers, melons and squashes, also grow well in hot locations, but they take up a lot of room. You might be able to fit some in if you have space around your beds to allow the vines to grow, or you can try growing up a sturdy trellis. There are varieties of zucchini developed for growing in containers that don’t sprawl as much as standard varieties. Beans and onions are other good options for sunny, hot spaces.
You can also grow cool weather crops like lettuce, beets, peas and carrots if you can get them in the ground soon. They might need some shade if your spot gets really hot, but lettuce, especially, can be planted, grown and harvested quickly enough that you can beat the hot days of summer. You can even grow it tucked into the shade of some of your other, taller plants. It’s also possible to plant different vegetables in succession to take advantage of both the cool weather in spring and fall and the hot weather of summer.
Most Mediterranean herbs will do well in a sunny location as long as you give them the appropriate amount of water. Lavender, sage, oregano, thyme and rosemary need less water, and basil, chives and parsley need more. Group plants with similar watering needs near each other. Mint does well in the Pacific Northwest, but can be aggressive so you might want to confine it to its own container to keep it from taking over.
Oregon State University Extension’s “Growing Your Own” guide to vegetable gardening (bit.ly/2Rf7S58) includes a chart listing planting times for different vegetables. It also includes information on preparing your soil, dealing with pests, and watering and fertilizing.
— Larina Hoffbeck, OSU Extension master gardener
Q: Last year, all of my tomato and squash plants got a form of powdery mildew on them that stunted the plants’ growth and drastically reduced the crop. After I noticed the mildew on the leaves and stems of the plants, I regularly trimmed any affected leaves/stems and sprayed the plants with water-diluted Neem oil. However, I was never able to eradicate the mildew.
Each time I trimmed the affected leaves/stems, I made sure that they did not remain in the raised beds, and at the end of the season, I pulled up all of the plants from the beds. For this year, is there any special soil preparation that I need to do prior to planting new vegetable starts to help prevent last year’s mildew from affecting this year’s crop? — Multnomah County, Oregon
A: When dealing with fungal issues like powdery mildew, prevention is far more important than trying to cure an already existing problem, so it’s great that you’ve already taken the step of cleaning your space of infected vegetable material. Make sure you’ve also cleared your planting area of any possible weed hosts and other debris, then you can turn your attention to avoiding a repeat problem this year.
The first step is to try to choose mildew-resistant varieties of the vegetables you want to grow. Seed packets and catalogs will list resistance to different diseases for each variety. If you buy vegetable starts at a nursery, carefully inspect them to make sure you’re not bringing in already-infected plants.
Next, make sure to plant in full sun, in a different area than these crops were grown in last year, if possible. Provide good airflow by spacing plants appropriately, staking them as necessary and pruning indeterminate tomatoes.
Avoid over-fertilizing your plants (a slow-release fertilizer will help with this), and water in the early morning. While overhead watering can wash spores from leaves, it is not recommended because it can lead to many other disease problems in vegetables. Use soaker hoses or drip systems, or you use a water wand if hand watering.
When using fungicides, it is important to start before you see symptoms or at the very first signs of disease, so make sure to inspect leaves daily. Some fungicides, such as sulfur, are protective, so use them before symptoms show up. Some, such as the various oils, are useful for eradication or control as soon as symptoms are observed. Neither work well after an infection has advanced. Read the labels on any fungicide you choose and follow the instructions exactly. And if you’re using a combination of fungicides, make sure to space applications appropriately so that you don’t damage your plants.
Further information can be found on the University of California’s page on powdery mildew (bit.ly/39NgVAA). Recommendations for fungicide use is at the bottom of the page.
Ask an Expert is an online question-and-answer tool from Oregon State University’s Extension Service. To ask a question, visit extension.oregonstate.edu/ask-expert.