By Jessica Carlson

Otter Tail County Master Gardener

Summer in Otter Tail County can bring some of the best gardening weather of the year, but it can also bring stretches of hot, dry weather. By July and August, gardens are growing quickly, vegetables are producing, and flower beds are in full bloom. This is also the time when we gardeners need to pay attention to soil moisture and adjust our maintenance routines. A dry spell does not mean everything in the yard needs to be watered every day. Watering needs depend on the plant, soil type and weather conditions. The best approach is to check the soil and give water to the plants that need it most.

In the vegetable garden ensure consistent moisture throughout the growing season, especially when plants are flowering and producing fruit. Tomatoes, peppers, cucumbers and beans all need adequate moisture during this time. A general guideline is about one inch of water each week from rain or irrigation, although sandy soil may require more watering. If the soil is dry about two inches below the surface, it is time to water. Apply water slowly at the base of the plants so it can soak into the soil instead of running off. Mulch can help conserve soil moisture. During severe drought, watering needs may change. Flowering and fruiting vegetables may benefit from smaller amounts of water every day or two rather than allowing the soil to become extremely dry between deep waterings. Avoid overwatering, since saturated soil contains less oxygen for plant roots. Watering at the soil surface also helps keep foliage dry and can reduce the risk of leaf diseases.

One problem some gardeners have noticed this summer is cucumber plants producing flowers but few cucumbers. Cucumber plants produce separate male and female flowers, and the first flowers are often male. This is normal, and female flowers generally appear as the plant continues to grow. High temperatures, drought stress and poor pollination can also affect fruit production. When conditions are hot, pollinators may be less active, and flowers may fail to develop into fruit. Cucumber flowers are pollinated by insects, so having flowering plants that attract bees and other pollinators can help. Avoid using insecticides when pollinators are actively visiting flowers. If your cucumber plants have plenty of female flowers but the small cucumbers fail to develop, check the soil moisture and make sure the plants are receiving enough water during flowering and fruit development. 

Established perennial plants can often tolerate short periods of dry weather, but newly planted perennials and plants growing in sandy soil may need additional water. During a dry spell, check the soil around the plants. For established perennials, check the top six inches of soil and water when it is dry. Water slowly and thoroughly so moisture reaches the root zone. Mulch can help conserve soil moisture, protect their roots and moderate soil temperatures. When water is limited, prioritize newly planted perennials and plants showing signs of drought stress. There is no need to water every established perennial simply because the weather is warm. Check the soil first and water when plants need it.

Annual flowers have only one growing season, so keeping them watered during hot, dry weather can help them continue flowering. Check annuals regularly, especially those growing in containers or in sandy soil that dries quickly. Water garden beds when the soil is dry and apply enough water to reach the root zone. Watering in the morning is ideal because it allows foliage to dry during the day. If plants are already wilting from heat or drought stress, however, do not wait for the next morning to water them. Avoid shallow watering, but do not keep soil saturated. Excess water can limit root oxygen and damage plants. Mulch helps reduce moisture loss and support plants in dry weather.

Our Minnesota lawns are made up primarily of cool-season grasses, which naturally slow their growth during the heat of summer. During a prolonged drought, Kentucky bluegrass may turn brown and enter dormancy as a way to survive. The grass can green up again when rain returns, and soil moisture is back to normal. If you choose to water during drought, water deeply enough to moisten the root zone rather than relying on frequent, light watering. Keep mowing heights at three to four inches and avoid unnecessary traffic on drought-stressed turf. Postpone mowing when the lawn is under severe heat and drought stress or when growth has slowed significantly. Do not fertilize a drought-stressed or dormant lawn. A brown lawn during a dry Minnesota summer is not necessarily a dead lawn. Allowing Kentucky bluegrass to go temporarily dormant can conserve water and help it survive until growing conditions improve.

Dry weather can be challenging for any gardener, especially in Otter Tail County where soil types and growing conditions vary from one property to the next. The best approach is to check the soil, watch the plants and use water where it is needed most.