Growing Organic Cucumbers

May greetings Portland gardeners!


As the weather warms I am interested in once again eating fresh salads, after a winter of soups. And for me salad means cucumbers! Cucumbers are a favorite warm season edible for the home gardener. A cucumber harvested at the peak of freshness from the summer garden is hands down better than any cucumber you will ever get from the grocery store.

Growing cucumbers in Portland is relatively easy if you plant them at the right time. Though we are eager, now is not yet the time. Cucumbers need ground temperature of 60-65 degrees and night air temperature of at least 55 degrees. Typically in Portland this is mid May to early June. If the weather is not warm and dry, cucumber plants will grow slowly and fall prey to disease.

Cucumis sativus, cucumbers, are member of the cucurbits family along with zucchini, summer squash, winter squash, pumpkins and melons. Cucumbers require a full sun location with at least 6 hours of sun per day. They are rambling vine plants that need to be spaced 3-4 feet apart in all directions. I have successfully grown cucumbers up a trellis in my raised beds. These days there are also patio varieties that don't get as large and are excellent for growing in small spaces including containers and raised beds. ‘Patio Snacker’ produced an excellent yield in my 2015 garden.

Cucumbers require very rich well draining soil. They will rot out in the thick clay of native Portland soil. Prepare your planting bed by adding fresh compost. Better yet grow cucumbers in a raised bed filled with fresh planting mix.

In Portland you can plant cucumbers by seed or by transplant. Cucumbers are “heavy feeders” and benefit from an organic granular vegetable fertilizer in the planting hole. Additional applications of organic granular fertilizer are every 4 weeks during the growing season. Once plants have grown to a decent size and are beginning to set flowers begin applying an organic liquid bloom fertilizer every 2-3 weeks.

More than 90% water, cucumbers are stressed by insufficient watering. Cucumbers want average to moist watering while growing, about 2 inches a week. Water stress can be the cause of bitter tasting fruit and odd shaped fruit that is smaller in one end. How often you water will depend on your soil and location.

The cucurbits family, including cucumbers, has separate male and female flowers on the same plant that require pollination for fruit set. If your plants develop flowers and then the subsequent tiny fruits fall off, lack of pollination is the cause. Be sure to plant plenty of flowers in your biodiverse garden to encourage pollinators and keep them safe by gardening organically and avoiding the use of sprays throughout your yard.

In Portland it is inevitable for cucumbers to fall prey to the dreaded powdery mildew. The leaves will develop a white residue and then shrivel up with crispy brown edges. Powdery mildew is a fungal disease that flourishes in the summer in Portland. During the growing season you can prevent powdery mildew by spacing your plants appropriately to provide good air circulation. Water the soil, not the plant, by use of a watering wand, drip irrigation or soaker house. If you use overhead watering the fungal disease easily spreads by splashing from leaf to leaf and soil to leaf. Practice crop rotation and in the fall clean up all plant debris.

Compost has long been recognized by organic gardeners for promoting overall garden health. Beyond stimulating plant growth, compost and compost tea can actually fight off diseases by inoculating plants with beneficial organisms like bacteria, yeasts and fungi. These tiny organisms are beneficial if they form a physical barrier against pathogens, or if they effectively compete with or attack the plant pathogens.

To prevent powdery mildew on cucumber plants, apply compost tea to your garden soil and as a foliar spray on cucumber leaves at 2-3 week intervals beginning at planting time. The great news for NE Portland urban gardeners is that our neighborhood nursery Garden Fever Nursery at 3433 NE 24th Avenue carries freshly brewed compost tea for sale by the gallon.

Be sure to plant your cucumber plants with dill plants for pickling later in the summer. Garden on Portland!

Warmly,
Jolie