When to Water Your Vegetable Garden

When to Water Your Vegetable Garden
How Often Should a Garden be Watered?
For daily wit & wisdom, sign up for the Almanac newsletter.
When is the best time to water your vegetables? How much should you water? See this helpful chart on how much water each vegetable needs and critical times to water. Plus, we’ll help you avoid some rookie gardening mistakes!
First: If you ensure your soil is amended with organic matter (such as compost), you are well on your way to healthy soil. Regular applications of modest amounts of compost—one-quarter inch per season—will dramatically improve your soil’s water retention and help suppress disease. See our articles and videos on soil types, soil testing, and the basics of amending your soil with NPK fertilizers and organic amendments.
When to Water
If your plants are in the ground (versus a pot), the general rule is that plants need one inch of water per week. However, this does NOT mean watering one time per week. That doesn’t usually do the job. Plants do best when watered deeply about three times a week, factoring in the rain. If the plants are seedlings, water them twice a day until established.
Read Next
But don’t just water without thinking. Feel your soil! When the soil sticks in your hand and you can form it into a ball, it is moist enough. But, if it barely holds together in the palm of your hand, or if the surface looks hard, baked, or cracked, it is probably dry, and it’s time to water. See if the soil is dry an inch below the surface; that suggests it needs water.
It’s best to water early in the day while the dew is still on the leaves so the foliage dries off by evening. However, if you can not water in the morning, watering in the evening is fine, too. Just avoid the middle of the day to avoid water loss to evaporation.
Believe it or not, sometimes the best time to water is during or immediately after a rainfall, especially if the rain shower amounts only to a half-inch or so of water. The reason for this is that you want to add sufficient water at the same time to ensure penetration down to 5 or 6 inches. If you wait another day or two to water, you will be adding only surface water, which evaporates rapidly. Light rain showers do not build up a reserve of water in the soil.
Lose Your Guilt About Wilt
Another sign is that the plants may wilt and look especially droopy. However, temporary wilting during the heat of midday does not mean that it’s time to water. Some plants go through an obvious midday slump, especially on very hot days, which is an indication of the plant’s natural adaptation to its environment. Visit your garden again in the early evening and see if the wilted plants have regained some turgidity. If they have come back—that is, if they look perkier—do not water.
How to Measure One Inch of Water
So what is “one inch of water” per week? First, an inch of water is defined as a one-inch deep layer of water over the entire soil surface that needs watering.
To measure one inch of water, you can either purchase an inexpensive rain gauge or try this DIY trick: Place 4 or 5 small containers (straight-sided) around the garden while the water during the rainfall. A tuna can is a good container to use. Mark 1 inch up from the bottom of the can. When 1 inch of water from rain or irrigation collects in the containers, that indicates that 1 inch of water was applied to the garden.
Again, don’t just rely on the “one-inch” guideline. If the soil is dry an inch beneath the surface, your garden probably needs watering. We also find it helpful to keep the following watering formula in mind: 1 inch of water per 1 square foot = 0.62 gallons.
How to Water Your Garden
What you want in a healthy plant is deep root penetration, and the only way that you’re going to get deep roots is if there is water down deep.
Start at the very beginning: Saturate each plant hole when you transplant seedlings. When you do water, make sure that you get the soil saturated enough that the moisture percolates at least several inches down.
Water at the soil level if you can; watering from above causes leaf disease. The disadvantage of using a sprinkler is that foliage is wetted by water dispersed via overhead application. This could lead to foliar diseases since the foliage remains wet for extended periods of time.
For a small garden, it’s fine to use a watering can, a watering wand, or a hose with a good nozzle that allows you to water right at the soil level near the plant.
If you have more dense plantings or larger plants, lay your hose directly on the ground near the plant so the water goes where it is needed. A board or rock placed under the water flow will prevent the water from eroding the soil. A good way to direct the water to the plants is to dig a little trench around the plants and allow water to flow into them.
If you have a larger garden with plants spaced one foot or more apart, consider investing in “drip irrigation.” This is done mainly with hoses or plastic tubes with small holes in them that deliver a relatively small amount of water directly to the root zone; by supplying optimum moisture, periods of water stress can be avoided. The hoses or tubes are placed down the rows, and water slowly trickles out.
Don’t Forget to Mulch!
Mulching is perhaps the #1 water-conserving technique for areas that receive less than 40 inches of rainfall annually. Organic mulches reduce evaporative moisture losses from the soil surface, and because the soil stays cooler, they also reduce transpiration water losses. Lay a thick layer of mulch down on top of the soil. (Do not mix with soil.) Renew mulches that are in place for the entire growing season.
How Much to Water the Garden by Vegetable
We recognize that folks with small mixed vegetable gardens aren’t going to water each vegetable differently. However, it’s very helpful to understand which vegetables are water lovers and the critical times when vegetables need water to thrive. If you plant vegetables in separate beds as we do (or in separate crop fields), it’s critical to give certain vegetables water at certain times.
Here’s a guide to help you estimate when and how much to water, assuming rich, well-balanced soil and little to no rainfall. Increase frequency during hot, very dry periods. (Note: Watering Formula: 1 inch of water per 1 square foot per week = 0.62 gallons)
In Conclusion…
Don’t baby your crops; plants are incredibly adaptable. They have the ability to draw water from deep in the soil. Periodically, take a trowel and dig down several inches into the zone where the roots are most active. If the soil there is still moist, there would be no benefit from watering.
Free Online Gardening Guides
We’ve gathered all of our best beginner gardening guides into a step-by-step series designed to help you learn how to garden! Visit our complete Gardening for Everyone hub, where you’ll find a series of guides—all free! From selecting the right gardening spot to choosing the best vegetables to grow, our Almanac gardening experts are excited to teach gardening to everyone—whether it’s your 1st or 40th garden.
This list is nice but I know VERY few gardeners that plant vegetables according to how they will be watered. Many (like myself) have small gardens and mix plantings. The "three sisters" Beans Corn and squash, have two that don't need heavy watering and one that does! So am I to no longer grow these three together? My peas have carrots and lettuce between them, so which do I pick for watering advice? I pretty much water when they look thirsty and when the soil is dry an inch or two below the mulch.
When I wrote promotional materials for Peters Professional Potting Soil and Plant Food, I discovered 30% of water is lost when irrigating by spraying water as opposed to using irrigation hoses.
I also find it interesting when experts suggest not to water a garden just before dusk, which supposedly can cause disease on wet plants. If this was true, then it had better not rain after 5 PM ever again in my garden! Plants seem to weather evening rain just fine.
The last two years or so, we have been plagued with mushrooms coming up between the sidewalks and the lawn and in-between planted pots. The varieties are unknown to us (one is the common looking white button-top and the other is an elongated pink, pointy-top one). We have two young dogs who seem very curious and we are afraid they might eat them and become sick. How can we rid ourselves of the "schrooms" once and for all. We have tried soap, salt, weed killer, and shovel to no avail. We live in Albuquerque, NM so no overmoisture here!