Watering Vegetables: Critical Watering Times

Lettuce seedlingsWater is essential for vegetable growth. Vegetables are mostly water: an ear of corn is 70 percent water, a potato is 80 percent water, and a tomato is 95 percent water. Vegetables will not grow and yield without consistent, even watering.

When to water. To know when your garden needs water, feel the soil and look at the plants. If the soil is moist and sticky, if it forms a ball in the palm of your hand, you do not need to water. If the soil does not hold together in your hand, it is too dry, and it is time to water. When plants wilt and look droopy in the morning, it is time to water.

Critical times for vegetable watering. The best rule is too keep vegetables and fruits evenly moist: if you stick your finger in the soil and it comes away damp, not dry and not glistening wet, the soil is evenly moist. Otherwise, review the paragraph above, and read the vetegable watering tips at the end of this post.

Critical times to get vegetable watering right:

Asparagus: during spear development and production and during fern development; less water is needed when ferns reach full size.

Bean, dried: during pollination, flowering, and pod development; blossoms may drop and pods may fail to enlarge if watering is inadequate; ¾ gallon per week per foot of row.

Bean, snap: during pollination, flowering, and pod development; blossoms may drop and pods may fail to enlarge if watering is inadequate; 1 gallon per week per foot of row.

Bean, lima: during pollination, flowering, and pod development of pods; blossoms may drop and pods may fail to enlarge if watering is inadequate; 1 gallon per week per foot of row.

Beet: consistent, even water throughout growing season and especially during root development to avoid cracking and knobby roots and hot flavor–symptoms of water stress; 1 gallon per week per foot of row or square yard.

Broccoli: consistent even moisture during entire growing season, especially early to prevent buttoning and during head development; 1 gallon per week per foot of row. Quality will be reduced if plants go dry at any time.

Brussels sprouts: consistent even moisture during entire growing season, especially early to prevent buttoning and during head development; 1 gallon per week per foot of row.

Cabbage: consistent even moisture during entire growing season; 1½ gallons per plant per week or 12 inches per season. Too much water during head development can cause heads to split; keep watering even.

Cantaloupe: during flowering, fruit set, and fruit development; 1½ gallons per plant per week or 18 inches per season.

Carrot: consistent, even water throughout growing season and especially during root development to avoid cracking and knobby roots and hot flavor–symptoms of water stress; ¾ gallon per week per foot of row or 18 inches per season.

Cauliflower: consistent even moisture during entire growing season, especially early to prevent buttoning and during head development; 1 gallon per plant per week. Quality will be reduced if plants go dry at any time.

Celery: consistent even moisture through the season; celery is shallow rooted and needs frequent irrigation; 2 to 3 gallons per square yard a week, 9 inches per season.

Collard: consistent even moisture during entire growing season; 1½ gallons per plant per week or 12 inches per season. Quality is reduced if plants go dry at any time.

Cool season vegetables: keep cool-season crops evenly moist during warm weather or heat.

Cole crops: consistent even moisture during entire growing season and especially during head development, but not bursts of water which can cause head splitting; 1½ gallon per plant per week or 12 inches per season. Quality is reduced if plants go dry.

Corn: corn requires consistent, even watering; water is critical during silking, tasseling, and ear development. Water when tassels on small cobs begin to shrivel and 10 days before cobs are picked. Water stress can cause tassels to shed pollen before silks on ears are ready for pollination; lack of pollination may result in missing row of kernels and reduced yields.

Cucumber: even, consistent watering during bud development, flowering, fruit development; 1½ gallons per plant per week or 25 inches per season.

Eggplant: even, consistent watering from flowering through harvest; 1½ gallons per plant per week or 18 inches per season.

Fruit trees: even water at flowering and again near harvest when fruit growth is most rapid.

Fruiting vegetables: consistent, even watering is required during flowering and as fruits start to swell; this will increase the yield.

Germinating seed: water frequently to keep the soil moist but be careful not to wash away seed.

Greens: consistent even moisture through the season; leaf crops are shallow rooted and needs frequent irrigation; 1 gallon per foot of row or 2 to 3 gallons per square yard a week, 9 inches per season; where regular watering is difficult do a heavy watering of 4 gallons per sq yard every 10 days.

Herbs: keep soil just moist, not wet; herbs do best with less water; wait until they begin to wilt; 1½ gallons per plant per week at most.

Kale: consistent even moisture during entire growing season; 1½ gallons per plant per week or 12 inches per season. Quality is reduced if plants go dry at any time.

Kohlrabi: consistent, even water throughout growing season and especially stem development to avoid cracking and knobby roots and hot flavor–symptoms of water stress; 1 gallon per week per foot of row or square yard.

Leaf crops: consistent even moisture through the season; leaf crops are shallow rooted and needs frequent irrigation; 1 gallon per foot of row or 2 to 3 gallons per square yard a week, 9 inches per season; where regular watering is difficult do a heavy watering of 4 gallons per sq yard every 10 days.

Lettuce: consistent even moisture through the season; lettuce is shallow rooted and needs frequent irrigation; 1 gallon per foot of row or 2 to 3 gallons per square yard a week, 9 inches per season; where regular watering is difficult do a heavy watering of 4 gallons per sq yard every 10 days. Do not let loosehead or iceberg types go dry during head development.

Melon: during flowering, fruit set, and fruit development; 1½ gallons per plant per week or 18 inches per season.

Onion: onions have small root systems; watering is critical during bulb enlargement; 1 gallon, per foot of row a week or 15 inches per season. Stop watering when tops fall over fall.

Parsnip: consistent, even water throughout growing season and especially during root development to avoid cracking and knobby roots and hot flavor–symptoms of water stress; 1 gallon per week per foot of row or square yard.

Peas: during flowering, seed enlargement, and pod filling; 1 gallon per foot of row a week or 18 inches per season.

Pepper: even, consistent watering from planting to fruit set and enlargement; 1 pint per plant a week when young, increasing to 1½ gallons per plant a week or 18 in per season.

Potato: even, consistent watering is best and especially during tuber set and enlargement; tubers will become knobby if they go dry during tuber development. Uneven watering at the end of the season can cause tubers to split.

Radish: consistent, even water throughout growing season and especially during root development to avoid cracking and knobby roots and hot flavor–symptoms of water stress; ¾ gallon per week per foot of row or square yard.

Root crops: consistent, even water throughout growing season and especially during root development to avoid cracking and knobby roots and hot flavor–symptoms of water stress; 1 gallon per week per foot of row or square yard.

Rutabaga: consistent, even water throughout growing season and especially during root development to avoid cracking and knobby roots and hot flavor–symptoms of water stress; 1 gallon per week per foot of row or square yard.

Seedlings: keep seedlings evenly moist, but avoid too wet soil which can cause damping off; water to avoid wilting early in the plant’s life.

Spinach: consistent even moisture through the season; spinach is shallow rooted and needs frequent irrigation; 1 gallon per foot of row or 2 to 3 gallons per square yard a week, 9 inches per season; where regular watering is difficult do a heavy watering of 4 gallons per sq yard every 10 days.

Squash: even, consistent watering during bud development, flowering, fruit development; 1½ gallons per plant per week or 18 inches per season.

Sweet corn: corn requires consistent, even watering; water is critical during silking, tasseling, and ear development. Water when tassels on small cobs shrivel and 10 days before cobs are picked. Water stress can cause tassels to shed pollen before silks on ears are ready for pollination; lack of pollination may result in missing row of kernels and reduced yields.

Strawberry: consistent, even watering during flowering and runner development.

Swiss chard: consistent even moisture through the season; spinach is shallow rooted and needs frequent irrigation; 1 gallon per foot of row or 2 to 3 gallons per square yard a week, 9 inches per season; where regular watering is difficult do a heavy watering of 4 gallons per sq yard every 10 days.

Tomato: consistent, even watering is critical during flowering, fruit set, and fruit enlargement; 2½ gallons per plant each week or 24 inches per season. More water may be needed for unmulched plants. Older late-maturing varieties may require less water near harvest.

Transplants: keep transplants evenly moist; water to avoid wilting as roots develop and take hold; the first 5 days are critical.

Turnip: consistent, even water throughout growing season and especially during root development to avoid cracking and knobby roots and hot flavor–symptoms of water stress; ¾ gallon per week per foot of row or square yard.

Vine crops: consistent, even watering is critical during flowering and fruiting.

Vegetable Watering Tips:

• Most vegetables need an inch of water per week. That is about 62 gallons for each 100 square feet; this amount will soak down to about 8 inches in the soil. Use a rain gauge to be sure your crops are getting the water they need. If rain is insufficient, you must make up the difference through irrigation.

• The best way to water is to deliver water to the base of the plant: use drip irrigation or small trenches that will allow the water to flow and seep into the ground. Sprinkler and overhead irrigation can result in foliar disease, especially if plants do not thoroughly dry before evening or cool temperatures.

• Drip and trickle irrigation systems are the most efficient and can place water very near plant roots. These systems have drip heads that can measure the amount of water delivered to the garden. To measure overhead watering, place 4 or 5 small straight-sided containers around the garden while watering; when 1 inch collects in the containers you have delivered an inch of water to the garden.

• The amount of water needed will depend on the type of soil in the garden: clay soil will hold more water than sandy soil and require less watering. Soil rich in organic matter is best; it is moisture retentive and well draining. Vegetables growing in containers require frequent monitoring and may require more frequent watering.

• Plants with healthy root systems will need water every 5 to 7 days on average unless the weather is hot or windy; temperature and wind can affect the soil’s water-holding capacity.

• Shallow-rooted vegetables require more frequent watering.

• Vegetables need more water when days are sunny and humidity is low.

• The best time to water is in the morning as plants begin to use water during the day. Watering in the heat of the day will result in a loss of water to evaporation. Watering in the evening can lead to foliar diseases if foliage does not dry before nightfall.

• Water when the air is still. Watering in windy weather will mean greater evaporation.

• Lightly cultivate around plants before watering–not deeply; this will allow the soil to accept and retain moisture.

• Long drip or trickle irrigation allows water to seep slowly and deeply into the soil and not run off. Watering to a depth of 5 to 6 inches encourages the growth of deep roots. Avoid quick, shallow watering which encourages shallow root growth. Shallow roots are more susceptible to damage by the sun and heat.

• Water before plants become wilted and stressed. When plants wilt the damage may already be irreversible. Plants that are wilted in the morning need water immediately. Check the soil moisture every day or two to make sure the soil is moist, not dry or too wet.

• Do not over water. Too much water can leach nutrients from the soil and drown plants; plant roots require oxygen from the soil to help plants grow.

• Mulch around plants to conserve soil moisture. Add aged compost and organic matter to the soil regularly. This will increase the soil’s moisture-holding capacity.

• Do not let weeds grow in the garden. Weeds compete with vegetables for water and nutrients.

• Grow crops in the right season. Cool-weather crops grown in early spring and fall require less water than if they are grown in warm weather.

• Harvest vegetables when they are young and just ripe. Young vegetables will require less water and will be tenderer and tastier than vegetables that sit in the garden past their peak.