Liz Douville

How should we garden in a drought? Maybe we need to learn to think like a plant.

The evidence of low-water tables is already in place with early water restrictions issued by several irrigation districts. The city of Bend has made statements they will do a better job of monitoring the city watering codes that have been in place for many years.

Does that mean someone else will take care of the problem? I think not. It is up to us to start thinking like a plant and understanding how plants use water. And perhaps even changing our vegetable selections if not this year, maybe some notes for next year.

It could be kind of fun to figure out how to create and maintain a more water-efficient garden.

Most plants absorb very little moisture through their leaves. Almost all the water they need has to get absorbed through their roots. The more roots they have, the better equipped they are to find and absorb moisture. A well-developed root system with lots of little sponge-like root hairs is a plants best insurance for survival in drought conditions.

For a plant to develop a good root system, the roots need to be able to push out into the soil. We are fortunate in central Oregon to not have clay or heavy soils.

That is not to say, the soil doesn’t need improvement and that is done by adding matter such as organic compost, and shredded leaves. Adding these materials will make your soil more porous, so water that’s applied to the soil surface won’t run off but rather will move into the root zone. Woody materials such as bark or wood chips added as a soil amendment, may result in soil nitrogen depletion and should be avoided.

A note I made in a garden journal regarding adding organic matter was “one-hundred square feet of good, loamy soil can absorb about 90 gallons of water, whereas 100 square feet of sand can only absorb 60 gallons.”

Plants don’t absorb very much water through their leaves, but they do lose water through their leaves. Another note from my journal quoted a reading stating that 98% of the water absorbed by a plant goes out through the microscopic pores (called stomates) on the plant’s leaves.

Apply water slowly to the base of plants. Soaker hose allows water to seep out all along its length at a slow rate. Use water timers added to the hose at the faucet to help reduce overwatering. Consider changing to either soaker hose or drip hose.

There are several ways to minimize the amount of moisture plants lose through their leaves. If natural shade isn’t available, think about constructing a simple lattice ‘roof’ that will provide simple shade and if wind is a problem, make plans to add the fabric row cover for simple protection.

Tall plants can be planted to provide shade for shorter plants. Sunflowers can shield the cucumbers.

Another recommendation is to plant in blocks rather than rows. This creates shade for roots and reduces evaporation. Be vigilant about pulling weeds as they are competing for any water that is there. Group plants with similar water needs on the same section of irrigation. Cucumber, zucchinis and squash require similar water applications. Irrigate when the top 2-4 inches of soil is dry to the touch.

With good soil organic content, the garden should be able to go 2-7 days between irrigations. Avoid heavy water use crops such as beans and sweet corn and crops that have fruit on the ground, such as melons, squash and cucumbers.

As a rule of thumb, water is most critical during the first few weeks of development, immediately after transplanting, and during flowering and fruit production.

The critical watering periods for selected vegetables include:

• Broccoli, cabbage, Brussels sprouts, kohlrabi and cauliflower need consistent moisture during the entire life span, especially during head or root development. Water use is highest and most critical during head development.
• Beans have the highest water use of any common garden vegetable, using 0.25 to over 0.50 inches of water per day. Beans need water most when they are blooming and setting fruit. When moisture levels are adequate the bean plant is bright, dark grass green. As plants experience water stress, leaves take on a slight grayish cast.
• Carrot and other root crops require consistent moisture. Cracking, knobby and hot flavor root crops are symptoms of water stress.
• Corn needs water most during tasseling, silking, and ear development. Yield is directly related to quantities of water, nitrogen and spacing.
• Onion family crops require consistent moisture and frequent irrigation due to their small, inefficient root system.
• Peas need water most during pod filling.
• Potato tubers will be knobby if they become overly dry during tuber development.
• Tomatoes, peppers and eggplant need water most during flowering and fruiting. Watch for overwatering.
• Cucumbers, summer and winter squash and other vine crops need water most during flowering and fruiting. Watch for overwatering.

The drought conditions have been evident for the past few years and will probably continue. Perhaps you can adapt some new techniques that will make a difference and make a claim to thinking like a plant.