Fact Sheet-10-16       Irrigating (Watering) Your Vegetable Garden                      Heidi Kratsch, Western Area Hortic...
careful you don’t provide water too rapidly or the water will begin                                  to pool on the soil s...
Plants should recover as the temperature cools          crown of the plant. Grass clippings should notlater in the day.   ...
A stake is used to position an emitter for a large plant or grouping of plants (left). Drip irrigation tubing can be snake...
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Irrigating Your Vegetable Garden - University of Nevada, Reno


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Irrigating Your Vegetable Garden - University of Nevada, Reno

  1. 1. Fact Sheet-10-16 Irrigating (Watering) Your Vegetable Garden Heidi Kratsch, Western Area Horticulture Specialist Water is a critical factor in the success of a vegetable garden. Plants need consistent amounts of water during the growing Water Delivery season in order to grow and develop normally. Any lapse in availability of water could significantly weaken your crops andHand watering with a hose affect the quantity and quality of your harvest. Applying too muchis common, but it is difficult water at one time leaches nutrients from the soil; applying waterto apply water evenly and too frequently limits root access to oxygen. It is important toconsistently to mature provide the right amount of water at the right time for healthy,plantings. Hand watering is productive vegetable plants.efficient for starting seedsand for watering containers. How much? How much water your plants need is a question ofUsing a fan nozzle will break how deeply and how often to water. How deeply you waterthe force of the water so you depends on the depth of the plant roots. Most vegetable plantcan avoid displacing seeds or roots go down 6 to 12 inches into the soil. However, long-seasondamaging young plants such as tomato, corn, squash and melon, and perennialtransplants. plants such as asparagus, raspberry and rhubarb can go down asFurrow irrigation works deep as 24 inches or more. Provide enough water to wet the soilwell for row plantings. to the depth at which most of the roots are found. You can checkFurrows work best when the depth of your irrigation by inserting a metal rod or screwthey are wide and shallow (3 driver into the ground after watering. When the rod meets withto 4 inches deep) and resistance in the soil (indicating you have struck dry soil), placesituated on level ground. If your thumb and forefinger around the rod at the soil surface andyour soil is sandy, water will pull up. The distance from your fingertip to the end of the rod tellsdrain too quickly and the you how deeply the water has penetrated the soil.water will not travel thelength of the row. In this How often? How often you water your plants depends on twocase, limit furrows to larger factors – your soil texture and the weather. Soil texture refers tocrops such as tomatoes and the size of the mineral particles in your soil. Sandy soils have largepeppers, creating a basin to particles with large air spaces in between; they drain quickly andhold water around the plant need to be watered frequently. Silty or clayey soils have smallerroots. particles; they will need less frequent irrigation because they hold more water. In fact, clayey soils drain so slowly that you have to be 1|Page
  2. 2. careful you don’t provide water too rapidly or the water will begin to pool on the soil surface and run off before it can reach theSoaker hoses are easy for deeper plant roots. If this happens, you should stop watering andthe beginning gardener. allow the water to soak into the soil before resuming irrigation. AnWater seeps out along the alternative is to use a slower method of water delivery such as aentire length of the hose for soaker hose or drip irrigation – water delivery methods aredelivery of water directly to discussed in more detail in the sidebar.the roots. Set the hose alongthe length of planting rows, The weather also influences how frequently you water. Plants takeor snake it around to cover up more water, and water evaporates from the soil surface morethe area in wider beds. quickly in hot, windy and dry weather. So, vegetables grown in theBecause water is delivered spring (cool-season vegetables) usually require less frequentslowly, it will take longer for irrigation than do vegetables grown in the heat of summer (warm-the water to reach deeper season vegetables). On a hot summer day, you may need to waterroots. Plan to leave a soaker your vegetables every day, but check your soil before you water tohose running longer than see if it needs it. You can do this by digging into the soil aboutyou would a sprinkler, and three to four inches and try to work it into a ball. Soil that fallscheck for depth of watering apart easily and barely holds together needs water. If the soil holdswith a stake or trowel. together easily without breaking apart, you don’t need to water.Drip irrigation is the most Most importantly, your vegetable plants will need more frequentefficient method of water watering when plants are young, until they establish an adequatedelivery. Ready-to-assemble root system.drip kits can be purchasedand provide everything you Container gardening. Many vegetable growers in urban areas haveneed to get started. The limited space for growing, and container vegetable gardening isbasic components include a becoming a popular way for people with limited space to havetimer, backflow preventer, access to fresh produce throughout the growing season. Vegetablevalve, filter, pressure plants that do well in containers include cherry tomatoes, peas,regulator, pipes, tubing and salad greens, hot and sweet peppers; and culinary herbs such asemitters. Fittings are used to basil, cilantro, oregano and thyme. Keep in mind that any plantattach to a host bibb growing in a container has a limited root volume of soil, so once(faucet) or they can be the water drains from the pot, it is unavailable to the plant. For thisscrewed on to a hose end. reason, vegetable plants in containers will need to be monitoredThe simplest systems have closely and watered more frequently than plants growing in thepre-installed emitters (inline ground. Some plants with large leaves, such as melon or squash,emitters) at set distances may wilt during the hottest part of the afternoon. This is becausealong the tubing. Drip they are losing water from their leaves faster than their roots canirrigation works well in take it up from the soil. Providing extra water will not help; put upsandy soils and on slopes, a temporary or permanent wind break, or provide afternoon shadewhere it minimizes runoff. to sensitive plants to protect them and conserve water. 2|Page
  3. 3. Plants should recover as the temperature cools crown of the plant. Grass clippings should notlater in the day. come from lawns treated with herbicides andConserve water. Water is important to the should be applied thinly to a depth of about 1healthy development of your vegetable plants, inch. Another mulch option is plastic or fabricbut water that doesn’t reach plant roots does sheeting, which must be laid down prior tonothing for your plants and costs you money. planting. Holes are cut into the sheeting, and aWater is wasted when it evaporates from soil single transplant is inserted into each cut hole.during the heat of the day and when it is applied Plastic sheeting heats up the soil in the springto unplanted areas and on paved surfaces. and may allow earlier planting of cool-seasonWater from high-pressure sprinklers can crops, but it can heat the soil too much inevaporate into the air even before the droplets summer and create heat stress for some warm-hit the ground. The following are tips to help season crops.you conserve water when watering your Use drip irrigation or a soaker hose. Dripvegetable garden: irrigation uses a system of polyethylene pipesWater early in the day. Temperatures are cooler and small tubes to deliver water at low pressureearly in the day, so there is less chance of directly to plants. Because water is delivered atevaporation from the soil or sprinkler heads. low pressure (5 to 30 pounds per square inch), itAlso, it is usually less windy earlier in the day, so is applied more slowly than with sprinklerwater from sprinklers stays on plants instead of irrigation. A soaker hose is similar to a dripblowing to other parts of your yard or onto irrigation system but is simpler in design. Apavement. Therefore, water applied early in the soaker hose is covered with tiny perforationsday has a better chance of soaking into the that force water out so it seeps slowly into theground where roots can take it up. ground, where it can replenish the soil water for plant roots. Evaporation is minimized with theseApply mulch. Mulching around your vegetable systems because the water is not thrown intoplants minimizes water evaporation from soil, the air as it is with a sprinkler, and the water isand has the added benefit of reducing delivered slow enough that plant roots have agermination of weed seeds that may be present chance to take up most of the water that isin your soil. In fact, keeping the weed applied.population down, in and of itself, can helpconserve water because water taken up by Above all, provide water frequently enough thatweeds is not available to your plants – weeds your plants don’t dry out, but not so much thatuse up precious water. Mulches appropriate for your soil stays wet. This means getting yourvegetable gardens include compost, straw (but fingers into the soil regularly to check its waternot hay due to presence of weed seeds), grass status. The better you are at observing yourclippings and shredded or ground wood chips. plant and soil condition, the more vigorous andThese should be applied to a depth of 2 to 4 productive your garden will be!inches and kept a few inches away from the 3|Page
  4. 4. A stake is used to position an emitter for a large plant or grouping of plants (left). Drip irrigation tubing can be snakedthrough a large bed to accommodate different plant arrangements (right).ReferencesKratsch, H.A. (Ed.). In Press. Water-Efficient Landscaping for the Intermountain West: A Professional and Do-It-Yourself Guide. Utah State University Press, Logan, Utah.Pittenger, D.R. (Ed.). 2002. California Master Gardener Handbook. University of California Agriculture and Natural Resources Publication no. 3382, Oakland, California.Whiting, D., C. O’Meara, and C. Wilson. 2008. Irrigating the Vegetable Garden. Colorado State University Extension, Colorado Master Gardener GardenNotes no. 714. Available online at http://www.cmg.colostate.edu/gardennotes/714.pdf.Wilson, C. and M. Bauer. 2005. Drip Irrigation for Home Gardens. Colorado State University Extension Publication no. 4.702. Available online at http://www.ext.colostate.edu/pubs/garden/04702.html.The University of Nevada, Reno is an Equal Opportunity/ Affirmative Action employer and does not discriminate on the basis of race, color,religion, sex, age, creed, national origin, veteran status, physical or mental disability, or sexual orientation in any program or activity itconducts. The University of Nevada employs only United States citizens and aliens lawfully authorized to work in the United States. Copyright © 2010 University of Nevada Cooperative Extension 4|Page