August Gardening Tips for the Pacific Northwest

Late summer marks the season for garden-fresh produce and flowers by the basketful. Get set to enjoy!

Irrigation Tips

Help plants beat the heat in the garden by keeping soil consistently moist. A one-two punch of mulch and regular irrigation is key.

If rainfall is scarce, water rhododendrons, azaleas, and camellias weekly. These shrubs are currently setting buds for next year's flower show, and drought will diminish bud formation.

You'll enjoy a healthy berry crop on hollies and firethorn when you irrigate shrubs during times of drought. Lack of water causes immature berries to drop.

After watering lawns and landscape plants, don't water again until the top 1-2 inches of soil has dried out.

Vegetable Harvest Guide

Visit the vegetable garden daily to ensure you're picking produce at the ideal stage. Overripe fruit on tomato, squash, beans, and eggplant prevents smaller fruits from maturing and can attract pests and diseases.

Not sure when to harvest? Follow these tips:

Cantaloupe. Netted skin indicates ripeness. Lift and twist fruits. If they're ready, they'll slip easily from the vine.

Carrot. For the best flavor, harvest carrots when they're on the small side: quarter size or smaller.

Green bean. Pick beans when they're as thick as a pencil.

Pepper. The fruits of many varieties change color as they mature. The longer peppers are on a plant, the hotter or sweeter they become.

Potato. Dig tubers when tops turn brown and fall over.

Summer squash. Look beneath leaves carefully to find all ripening fruit. Squash tastes best when it's small.

Tomato. If possible, let fruits ripen on the vine to sample sweetest flavor.

Test Garden Tip: In the strawberry patch, choose the strongest, largest plants to bear next year's crop. Remove remaining plants, including runners. Fertilize and water regularly to yield an outstanding berry crop next year.

August Planting Tips

Along the Coast Replace early summer veggies with fall crops of broccoli, cabbage, and cauliflower. You can also plant salad fixings, like lettuce, beets, spinach, and radishes. Replace spent annuals with new ones. Give the garden a fresh look by trying something new. Choose larger plants to create a strong show from now until frost.

The best cold-tolerant veggies.

Throughout the Region Buy fall bulbs as soon as you spot autumn crocus (Colchicum) at garden centers. Plant this crocus as soon as you get it. Spring-flowering bulbs should go in the ground after Labor Day. Late this month, lift and separate spring-flowering perennials and bulbs. Now through mid-September is the best time to establish a new lawn. Check with a local nursery to get the grass that's adapted and ideal for your specific area.

Battle Pests

Check tomato plants for large green worms called tomato hornworms. If you spot worms covered with things that look like rice grains, leave them alone. Each "rice grain" is a cocoon of a predatory wasp, which feeds on pests (don't worry -- they don't sting humans or other animals).

Yellow jackets and wasps are more active this time of year. Unless these insects are endangering an outdoor living area or your home's structure, leave them alone. They consume problem insects.

Holes on leafy vegetables are likely the handiwork of caterpillars. Spray Bacillus thuringiensis to combat them naturally.

Corn earworms may infest early corn. Check forming ears regularly and treat new silks as needed.

Don't spray pesticides during the heat of the day -- you risk injuring plants. Wait until evening, when temperatures are cooler. If rainfall has been scarce, water plants a few hours before spraying.

Stop garden pests.


Prune caneberries (such as boysenberries and raspberries) after harvest. For June-bearing plants, cut canes that fruited this year to the ground. For everbearing plants, prune canes that bore fruit this season by half. The remaining half of canes will bear fruit again next year.


Start a compost pile for garden and kitchen refuse. Don't add diseased plants or weeds with ripening seeds unless your pile gets hot. Remember to water compost piles throughout summer to facilitate decomposition.

Learn how to make compost.

Herb Gardening

Harvest herbs early in the day, after dew has dried. Air-dry herbs on a screen or by hanging bundles upside down in a cool, dry spot. You can also dry herbs in a dehydrator. Store dried herbs in airtight containers.


Continue deadheading flowering annuals and perennials. This simple task is key to encouraging the formation of more flower buds.


Stop applying fertilizer to perennials, shrubs, and trees -- they're starting to harden off now for winter and extra nutrients this time of year can make them less hardy.


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