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Watering the yard and garden in extreme drought

Brown house entry with brown rain barrel, green shrubs, a wood planter and green and yellow perennial plants located under a window.
Use raked leaves as mulch around trees, shrubs and perennials. Save time later this fall by cleaning empty rain barrels now.

A few weeks ago, we published an article about watering wisely in drought. Basic practices like watering in the morning and using mulches to keep the soil moist remain very important. Prioritizing what to water and re-using water safely will also help keep our landscapes healthy during extreme drought conditions . 

An inch per week? Choosing what to water

Due to watering restrictions, fears of wells running dry, and simply wanting to conserve water, many of you are probably prioritizing which plants need water the most.

The common saying that gardens need an inch of water per week is a good rule of thumb. But, in extreme drought conditions, many of us are wondering how to prioritize watering. Which plants actually need an inch per week and which plants can get by with less?

Here’s a quick guide to help you prioritize. 

Water trees young and old - and shrubs too!

Mature trees need water yet are some of the last plants we think about due to their size and the fact most leaves are well above our eye level.

Saturate the top 6-9 inches of soil with water to ensure those important feeder roots are well-watered. Most tree roots are located in the top 18-20 inches of soil and spread far beyond the dripline (canopy edge) of the tree. Small, but effective, feeder roots are responsible for much of the water and nutrients the tree receives from the soil.

Read more about How to water established trees and shrubs.

Late summer and early fall can be a good time to plant new trees and shrubs. Again, be sure to water them. Visit How to water newly planted trees and shrubs for a formula for how much and how frequently to water. Note that daily watering 1-1.5 gallons per inch of trunk diameter is required for the first two weeks after planting.

Evergreens need moist soil as we move into winter in order to reduce needles drying out. Think of each needle as a leaf. Deciduous trees and shrubs drop their leaves, but evergreens have to hang onto them through the winter and spring. Adequate water helps.

Focus on perennial flowers

Are you getting tired of watering your containers every day? We sure are! Annual flowers are wrapping up their lifecycles for this year, so concentrate your water resources and effort on your perennials and bulbs that will be there next year.

And speaking of bulbs, September is a good month to plant spring bulbs like crocus, chionodoxa, daffodils, tulips — and garlic! Be sure to plant in well-drained soil and water bulbs like you water your perennials.

Wondering if your perennials are dry? Get your hands in the soil and water if the top 6 inches of soil are dry. 

As you start raking leaves, put them around your perennials, trees and shrubs as a mulch. Mulch holds in soil moisture while protecting roots, moderating soil temperatures, and overall reducing stress on our landscape plants.

Don't over water vegetable gardens

We’re actually receiving quite a few photos this year of vegetables that have received too much water. Likely due to concern over the drought, many gardeners seem to be overwatering their vegetables.

Some vegetables are hardier than others, and each vegetable has a critical period when consistent water is especially important for high quality fruit, root, tuber, or bulb set. Usually this period falls between flowering and fruit maturation. 

  • Pay extra attention to vegetables that are flowering and fruiting. These vegetables need consistent moisture. Watering a little bit every day or two is better than watering all at once. 
  • Storage crops reaching their time of harvest like potatoes and onions can be cut off from water at this point in the season if you plan to harvest in the next few weeks. 
  • Deep rooted vegetables like tomatoes, squash and melons can pull moisture from deep in the soil, and so they tend to be hardier than some other common vegetables. 
  • Sweet corn has very shallow roots and needs water more frequently. 
  • Cool season crops like lettuce, broccoli and turnips need frequent water throughout the summer. 
  • Vegetables grown in pots need to be watered every day. 

Re-use water

While most of our rain barrels have been pretty empty this summer, gardeners are finding other ways to conserve and reuse water, such as using dishwater, water from coolers, and even capturing water from the shower in buckets to water their plants.

  • Avoid reusing dishwater that contains a lot of soap as it can burn foliage especially when applied in hot sun.
  • Don’t reuse water that has had meat or bones cooked in it as the fat residue can attract animals.
  • You can reuse water used to cook vegetables, just let it cool down first before applying. 

Take advantage of your empty rain barrels to clean and disinfect them for next year. You can read how here: How to clean and care for a rain barrel.

Authors: Natalie Hoidal, local foods educator; Annalisa Hultberg, food safety educator; Julie Weisenhorn, horticulture educator

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