Proper watering is vital

Watering … how much, when, and where, are questions gardeners are dealing with during this severe drought. The standard knowledge is one inch of water per week for keeping lawns in good shape. For clay soils this may be adequate, but sandy soils drain faster and may need water more often.

Green And Growing

By Linda G. Tenneson

Moisture needs to reach plant roots instead of evaporating into the air. Clay soil may take longer to absorb water than sandy soil; so, watering clay soil should be done with a lower water pressure to allow water to be absorbed before it can run off the surface. Mulch helps with retaining soil moisture.

Plants draw water from the soil and carry nutrients from the roots to all parts of the plants. A lack of water reduces the amount of nutrients that can travel to all parts of the plant. Water delivery methods are also important. Spraying water with a hose and sending it through the air results in some of the moisture being lost through evaporation instead of landing on the soil and sinking into the ground. A sprayer which sends water out in a horizontal path instead of a vertical arc can reduce the amount of moisture lost through evaporation.

Both sprayer versions result with water landing on plant leaves and stems as well as on the soil. Wet leaves which are not allowed to dry off before late evening are more likely to become infected with fungal diseases. Water that lands on leaves and stems midday can evaporate before landing on the soil and benefiting the plant roots. However, if plants are wilting, watering is necessary — even if it is done in the middle of the day.

The human finger is a good tool for determining when shallow rooted plants need water. Stick your finger into the soil. If it comes out dry, the soil needs water. Soil that is dry more than two inches below the soil surface needs to be watered.

A better method to deliver water to plants is to use a soaker hose. Soaker hoses have tiny holes in their sides and allow water to sink into the soil removing the possibility of water loss through evaporation. A device allowing more than one hose to be attached at the same time can send water out to several locations.

Monitoring the amount of water that plants receive is also important because too much water can stop oxygen in the soil from being accessed by the plant roots. Plants differ on how much water they need. Therefore, watering may be needed more in one part of the garden than in others. Rain gauges are useful in checking to see if enough rain has been received to equal an inch or more per week.

When choosing plants, look for ones that are drought tolerant. The web sites extension.umn.edu/how/watering-vegetable-garden and extension. umn.edu/planting-and-growing-guides/ watering-established-trees-and-shrubs contain additional information on watering. The University of Minnesota also has a downloadable publication, “The Best Plants for 30 Tough Sites” that is helpful in choosing drought tolerant plants.

Linda G. Tenneson is a University of Minnesota master gardener and tree care advisor. v