By David Whiting, Carol OMeara, and Michael Bauer, Colorado State University Cooperative Extension, Horticulture
In vegetable production, an adequate supply of water during the growing season is directly related to produce quality and yields. Unlike bluegrass and other landscape plants, vegetables cant go dormant when the water supply is inadequate. However, there are several techniques that will significantly reduce the water requirements of the home vegetable garden.
No current watering restrictions:
The following practices will allow you to have a productive vegetable garden and still reduce water consumption.
Amend the garden soil with organic matter
In the vegetable garden, the routine addition of soil amendments such as compost will optimize potential yields and produce quality vegetables.
As a human health (e-coli) issue, the application of manure or compost made from manure should be made at least 4 months prior to harvest of any edible crops.
Manure and compost made from manure may be high in salts that will interfere with crop growth. Do not add more than 1" of manure or compost made with manure without a soil test to evaluate potential salt build-up.
Incorporate organic mulches into the vegetable garden soil after the season is over to add organic matter and improve soil moisture retention.
Replant your fall garden with a green manure crop such as winter rye or Austrian peas to add organic matter and improve soil water retention.
Practice efficient irrigation
Drip or trickle irrigation is ideal in the vegetable garden, reducing water usage by about 50%. The soaker hose is probably the least expensive and easiest to use in a vegetable garden setting. Known as a "leaky pipe", it is a hose that allows water to seep out all along its length at a slow rate. They typically run, at low pressure, for only 10 to 15 minutes per irrigation. There are also tubes with holes for the water to drip out. Another option is a simple 'hose bubbler' which is a hose end attachment to irrigate the base of a plant.
Check soil moisture regularly to avoid over-application. Squeeze soil in your hand; if it sticks together, it is moist and irrigation should be delayed.
Place soaker hoses or drip irrigation under the mulch used in the vegetable garden.
Know the critical watering periods for vegetables and you can target the timing and amount of water to add. 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 follow:
Water during early morning, when wind is low and temperatures are cool.
Mulching minimizes evaporation of water from the soil surface, reducing irrigation need by around 50%. In the vegetable garden, use an organic mulch to a depth of 1-3 inches, depending upon the particle size of the mulching material. The larger the particle, the thicker the depth of mulch that should be applied. Mulch only after the soil has warmed sufficiently. Do not use wood or bark chips in a garden setting that requires annual soil preparation. The chips will interfere with future seedbed preparation.
Grass clippings make excellent mulch for the vegetable garden. Apply fresh clippings in thin layers (up to ¼ inch thick) and allow each layer to dry before adding more. The clippings quickly dry down and additional layers can be added weekly. Do not place fresh clippings in thick piles, as they will mat, decay and smell foul. Do not use clippings from lawns that have been treated with herbicides or other pesticides in the past month. A couple of sheets of newspaper may be used under the clippings to help control weeds. Do not apply newspapers more than a couple of sheets thick, or a soil carbon to nitrogen imbalance may occur. Do not use glossy print materials, their inks may not be soy based like newspapers.
Black or colored plastic mulch conserves moisture and also increases soil temperatures. They are used on tomatoes, peppers, eggplants and the vine crop family (cucumbers, summer and winter squash, melons). Lay down plastic early in the season so plant growth shades the plastic from extreme summer temperatures. Do not apply plastic in mid summer. Do not use plastic on other crops.
Plant in blocks, rather than rows. This creates shade for roots and reduces evaporation.
Control weeds, they are competing with the vegetables for the water supply.
Group plants with similar water needs (i.e. families) together on the same soaker hose. Cucumber and zucchinis and squash, for example, require similar water applications.
Check the soil for moisture before you water. If the soil has dried out to a depth of 2-4 inches, plan to water. This is especially important if using mulch, where water can be held in the soil for longer periods of time.
Provide windbreaks to reduce evaporation of moisture from soil and plants.
With good soil organic content, a standard in vegetable production, the garden should be able to go 2-7 days between irrigations. Restrictions limiting irrigation to every 2 or 3 days should not have a major impact on the vegetable garden.
Care for the vegetable garden when no watering is allowed:
Dont plant a vegetable garden. Vegetables do not go dormant like a Kentucky bluegrass lawn. Consider planting a couple of containers with vegetables.
Photo: Judy Sedbrook
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010