Guest Contributor: Cassey Anderson, Horticulture Agent, Colorado State University Extension
Drought is a topic on many people’s minds this year after an abnormally warm and dry winter throughout the western US. When water restrictions go into play it can become more of a challenge to ensure your vegetables get the water they need. It is always important to follow local regulations regarding your water use. But today, let’s look at what water does for our plants and how you can ensure the water you use goes to the best possible use – food!
Why Plants Cannot Perform Without Consistent Water
Plants require water to grow, to flower, and to produce good and tasty fruit. Water stress can lead to stronger or unpleasant flavors (if you’ve ever left a radish alone for a season and forgotten to water it you know what this is like!) Unlike some of our ornamental plants and lawns, our vegetable plants are unable to perform with less water. Broccoli, for example, becomes bitter when drought-stressed and the flavor will never recover fully.
There are several critical periods for good watering habits in most of our vegetable plants. When you plant a seed or transplant a seedling you need to ensure the soil remains moist for good germination and establishment. For a plant to produce effective flowers that will grow into tasty fruit they need consistent watering. This may look different for different crops.
Carrots, for example, require consistent moisture throughout their growth or you may see roots split or develop strong or unpleasant flavors. Vine crops such as cucumbers or squash need water most as flowers and fruit are developing. They can tolerate less water prior to these stages. For most crops, however, consistent watering is key to developing the best produce. For many vegetables, if you begin to see wilting it is a sign that you need to water. However it’s always good to check the soil as wilting can also be a symptom of disease, insect pressure, or overwatering.
How to Get Water Where It Needs to Go and When
How do you know you’re getting water where it needs to be? You can check! You can use your fingers and a screwdriver to assess if the soil is moist at least 6-8” deep into the soil profile. Watering slowly and deeply and then letting the soil dry in between watering is going to keep your water bill lower and your plants growing strong and healthy. You have other options as well which we’ll dive into now.
When to water? It is best, typically, to water outside of the peak heat of the day. Try to avoid watering between 10 AM and 6 PM. If you live in a dry climate, watering overnight can be a great option. If you face humidity, try to water in the morning or in the evening.
Drip Irrigation, Soil Health, and Mulch Make Every Drop Count
By installing a drip irrigation system into your vegetable garden you can ensure that only the plants you are trying to grow are getting water. While overhead irrigation is inexpensive to set up it can lead to increased disease pressure and wasted water due to evaporation. Drip irrigation is easy to build and customize to fit the needs of your specific garden. Determine what type of drip irrigation you want to use:
• Soaker hose - inexpensive, puts a lot of water down quickly but can break down after 1-2 seasons.
• ¼” Dripline with in-line emitters – lasts longer than soaker hose, covers a lot of area effectively and can be moved around to customize what is being irrigated.
• ¼” Line drip emitters – can be purchased in varying levels of water from ¼ gallon/hour up. Some can be adjusted, some cannot.
• Drip tape – often ideal for larger garden set-ups this lays flat and in a line and can be very inexpensive to replace. May require a little extra planning for connection to your water source
When considering installing a drip irrigation system there are several components to add to the mix that will ensure success. Be sure to install a backflow preventer which reduces the chances that any microbes in your irrigation line can suck back into your main water supply. You will also want a pressure reducer. This ensures that your household water pressure doesn’t blow out the pressure bladders in your drip emitters. Most systems are designed for pressure between 15 and 30 PSI.
Soil Organic Matter - The next important thing you can do to improve water retention and efficiency is to ensure your vegetable garden soil (if in raised beds or in-ground) has soil-organic-matter (SOM) that is around 4-5%. This number may feel low, and often new gardeners are tempted to add 50% compost to their beds, but when SOM is too high it can lead to issues of nutrient availability for several seasons until SOM reduces. If you have high levels avoid adding more and plant densely. You may need to supplement with additional fertilizer for a season or two until things settle down. The best way to determine where your organic levels are is to do a professional soil lab soil test. SOM levels between 4-5% do many things for your vegetable garden, but regarding moisture they ensure that clay soil clumps and has better drainage, and help sandy soils to retain water better.
Mulch – Last, but not least, in the effort for helping our water do as much as it can in our gardens let’s talk mulch. Mulch is any material we use on the surface of the soil. It can be organic – as in it came from something living such as grass clippings or straw (buy weed-free herbicide-free straw for best results). Other organic mulches such as wood chips, wood shavings, or even collected leaves have challenges when used in a vegetable garden. Using organic mulches can help insulate the ground, keeping it cooler which reduces evaporation water loss.
Inorganic mulch can also be an option – Typically for vegetable gardens these include materials such as plastic sheet mulch, landscape fabric, paper mulch etc. Plastic mulches will often heat the soil, but less water may be lost with some types if they are not permeable. Use your best judgement, or work with your local Extension office to determine what mulch fits best for your situation.
When installing mulch, it is good to wait until plants have germinated or transplants are established, to install drip irrigation under the mulch, and to keep a thick layer to both provide better insulation and to reduce weed germination.
A Few More Ways to Reduce Water Loss
Other things you can do:
• Plant densely, when possible, to shade the soil
• Pull and control any weeds that may take up available water
• Use a windbreak to reduce water loss from the soil
There are, of course, other things you can do but these are some great approaches to be more aware of water and its role in the vegetable garden. Again, although vegetable plants are not tolerant of water reduction, there are many strategies you can use to reduce water use while still getting the water your plants need to them
As always, reach out to your local Extension office for further information if you have any questions.
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