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Monitor Soil Moisture

August is the warmest and driest month of our Pacific Northwest year. Your garden needs 1 inch of water per week to remain productive. Two to four inches of mulch will help retain soil moisture, so you don’t have to water as often.


There are sensors that will tell you how much moisture is in the ground, but a very simple and readily available method is to use your finger. Pull the mulch aside and push your finger into the ground to your second joint. If the tip of your finger feels cool, you can wait a day or two.


Container plants will need watering every day, and if it is particularly hot, twice a day.

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Photo used with permission

Whether your sensor is low-tech or high-tech, keep monitoring that soil moisture.

Clean Up After the Harvest

As your summer vegetables finish producing, clean up the rows, compost any remaining material, and pull and compost the weeds (if they have not gone to seed). Composted material will protect and enrich the soil.


Decide if you want to till the soil for weed control and to get it ready for fall or spring planting. Plant a cover crop on any areas you don’t plan for a fall garden. Cover crops eventually need to be turned over to die and decompose to replace nutrients and organic matter in the soil.

Start Your Fall Garden

Many vegetables enjoy the cooler months of fall and now is the time to plan and plant for that period. Also consider those plants that you can harvest during the winter. Parsnips taste best after a frost; carrots and other root crops can be dug as long as the ground doesn’t freeze, so you might want to leave some for later harvest. Kale will withstand light frosts and can be harvested most of the winter. Garlic is traditionally planted in the fall, grown over the winter, and harvested in the spring and summer.

Harvest and Dry Your Herbs

Many of the most flavorful herbs enjoy a Mediterranean climate — hot and dry — which concentrates their essential oils. August is ideal for capturing that flavor. Humidity is low, facilitating drying. Basil loves the warm weather but will go to seed as the days shorten. You can prolong your basil harvest by keeping the flowers pinched out.

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Photo used with permission

Herbs at the Master Gardener Educational Gardens at Greenbank Farm are ready for harvesting and drying.

Prune Cherry Trees

Cherries are particularly susceptible to bacterial diseases. Free moisture (rain) facilitates the movement of bacteria. Cherries also bleed readily when soil moisture is high (gummosis). Pruning during August minimizes disease transference in cherries and gives the tree time to heal the edges of cuts before winter can damage the new tissue.

Plant Flower Bulbs

Bulbs ordered earlier in the year are being shipped now. Get them in the ground so they can develop roots and be ready for spring blooms.

Authored by Scott Hagues, Island County Master Gardener
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