How Much Water Do Vegetables Need?

Watering plants regularly is very important for successful gardening.

Giving your plants ample water is one of the most important tasks of a gardener. If rainfall doesn’t provide enough, you have to make up the difference.

A good general guideline is an inch of water per week, either by rain or watering; in arid climates, it is double that. In hot weather, vegetables need even more water, up to about ½ inch per week extra for every 10 degrees that the average temperature is above 60 degrees.

By definition, the average temperature is the daytime high plus nighttime low, divided by 2. So, if the high is 95 and the low is 73, the average is 92 + 73, divided by 2. The answer is 82.5. In this case, the garden needs at least another inch of water. This explains why most vegetable gardeners in hot climates just laugh at the “1 inch of water per week” recommendation. That simply doesn’t work in really hot weather for squash, eggplant, tomatoes, and other crops that need lots of water and have big leaves that wilt easily.

You can measure an inch of water by putting a rain gauge or even a plastic container or other container under your sprinkler, soaker, drip, or other watering system. You’ve applied an inch of water when the vessel collects water an inch deep.

27 Comments

Sheila Rotter

I live in CA and am trying to grow tomatoes, lettuce, peppers, cucumbers. I really don’t understand your 1/2″ or 1 inch watering. They are in a small plot of land and I have an automatic sprinkler on everyday for 10 minutes Is that too much or too little?
How do I measure the soil by sticking a pencil or another wooden piece in the grown? I would also like to knows about my roses and other flowering plants. Thanks.

Danielle Carroll

Hi Sheila,
An inch of water is about 60 gallons per 100 square feet. To measure how much water your garden is receiving, place a pan or water gauge in your garden to catch the water from your sprinkler and measure. Ideally, you want to water deeply a couple of times a week once your plants are established. Water so that the garden soil is moist about 6 inches down. This encourages deep root systems. The amount of time to water will depend on the soil type and the temperatures outside. Sandy soils drain faster (and will need more water) than other soil types. I hope this helps. – Danielle, Bonnie Plants

Peter

You can purchase a water meter that attaches to your water hose and gives the exact amount of water you are distributing in either litres or gallons, you chose which unit of measure you want. measure the size of your garden that you are watering in square feet and then multiply that by 0.63. This will give you the number of gallons of water needed each week as a base amount. If your general weather is hot, say average temperature is approaching 80 degrees F then your water needs may be between 1 and 1/2 to 2 times as much water. Remember that we are talking gallons per week. So if you water every other day then divide the total gallons required per week by the number of times you water each week. Best to use a soaker hose as this places the water directly into the soil and dose not wet the leaves which generally just gets drawn off by the sun.
Lee Valley sells one of these water meters for about $12.00. You will find it very handy as each soaker hose or drip irrigation system and nozzle feeds water at different rates.

Craig

What do you mean an inch per week? An inch in a length not a volume of water.

Danielle Carroll

Hello Craig,
An inch per week is roughly 60 gallons per 100 square feet. Inches is determined by rainfall. The best way to measure is with a rain gauge to see exactly how many inches have fallen. – Danielle, Bonnie Plants

Leslie

I have been watering my tomatoe plants a little everyday but I’m noticing they are starting to turn yellow.
Does this mean I’m watering too much?
I have two tomatoe plants in pots
I haven’t fertilized them yet

Danielle Carroll

Hi Leslie,
Tomato plants will start to turn yellow for a number of reasons – lack of fertilizer, insects, fungal diseases, and even too much water. If they have not been fertilized yet, the plants are probably hungry for nutrients especially if you didn’t mix a slow release fertilizer in with the potting mix. Containers typically need fertilizing more often since they require more water than veggies planted in the ground. Containers should be watered when the top inch or so of soil has dried. -Danielle, Bonnie Plants

Andre Michaels

Why does Miracle Grow draw Spider Mites to my tomato plants?They have
Desimated my plants to the point I have to take them out of the ground and replace them. And there is nothing on y
The market to get rid of them

Danielle Carroll

Hi Andre,
I am not sure why fertilizer would attract spider mites unless the plants were well overfertilized. And the spider mites were drawn to the rich, green growth. – Danielle, Bonnie Plants

Naomi Caslin

As for your spider mite problem, try gardensalive.com. They are a company located in Indiana that sell all natural and organic based products. I only use there products and my plants always look great. And yes, there stuff works great against spider mites.

John Merchant

I have three raised beds all with soaker hoses .My question is how long to run the hoses to get 1 inch of water . Is it best to give the whole inch at one shot or spread it out?
Thanks

Danielle Carroll

Hi John,
Once vegetables become established, it is best to water deeply – a couple of times per week. Shallow watering every day can result in shallow roots and a soil that dries weekly. To get a handle on an inch of rain – that would be about 60 gallons of water per 100 square feet. I would water the raised bed until the soil is wet 6 inches down. Wait a day or two and see if the soil is still moist or if it needs watering again. Sometimes it is hard to tell how much water comes out of a soaker hose. You can try by placing a pan below it to catch the water while it is running.
-Danielle, Bonnie Plants

Katy

What is the best time of day to water the garden? And should this apply to a flower garden (roses) as well as veggies?

Thank you!!

Danielle Carroll

Hey Katy,
Early in the morning is a great time to water. Less water is lost to evaporation (wind and heat). If you have to overhead water, leaves will dry off quicker in the sun than if they were wet at night. To save and conserve more water, try these water saving tips.
-Danielle, Bonnie Plants

Francis

The squirrels dig up the dirt in my pots and flower baskets! Please, can anyone help me with a sound solution. I live in a metropolitan city neighborhood, with a big back yard.

Danielle Carroll

Hello Francis,
Living harmoniously with squirrels is sometimes hard to do. I have seen containers lines with chicken wire at the top to hinder the squirrels from digging. A little potting soil was placed over the wire so it did not show. Others have had success with deterrents with black or hot pepper.
Happy Gardening,
Danielle

Marshall

a little cayenne sprinkled in the pot will keep the pests at bay

Esther

I am planting a cauliflower plant and a broccoli plant (southern California). How often should I water them if there is no rain? Also, when should I start fertilizing them?

Mary Beth

Hi Esther,
As this article states, the average is an inch per week. We give you details above how to gauge what that might be using irrigation or sprinklers. ALso, you might find this article on when it’s most crucial for vegetables to receive watering, as they are developing fruit or in certain stages. Check out this article on How To Grow Cauliflower for a step-by-step on fertilizing and harvesting. Happy gardening. ~Mary Beth, Bonnie Plants

slobodan

I would like to know how much water do i give a tomato plant that is in a 3 gallon clay pot,and i also bought the bonnie herb and vegetable plant food do i also water the leaves with this product to keep the bugs away? thanks

Mary Beth

Clay pots seem to release moisture faster than others, so you may have to water your tomato daily in higher temps. Check the soil moisture by feeling the soil up to your first knuckle. If it’s dry, time to water. Use the diluted Bonnie Herb & Vegetable Food when you first plant the transplants and again several weeks later in the middle of the season. You don’t want to overfertilize tomatoes or you will have tall, leafy green plants with little fruit. It’s best to water and fertilize at the soil level, not on the leaves, to avoid unnecessary moisture on the foliage that might invite disease. You’ll also want to ensure you have the right plant in the right size pot. Some tomatoes are better than others in smaller pots, while you will need at least a 24″ diameter for most varieties. Happy growing ~Mary Beth, Bonnie Plants

ann

i am growing peppers for the first time , the air conditioner was replace and the tech rerouted the hose from the unit to my peppers. This morning i notice a lot of water in the pepper bed, is this a good idea or should i relocate the hose? Should my garden be on the dry side? I have lots of peppers and lot of new flowering. SS, Md

Kelly Smith Trimble

Hi Ann, Sounds like a great idea (free water!) to me. You might direct the hose into a bucket instead of directly into the bed if it seems like the plants are getting waterlogged, but if they’re just getting the same amount that you would give them if you were watering, I’d say leave it be. Sounds like the plants like it! Happy growing! Kelly, Bonnie Plants

jeanie

Hi, You guys are great! Can I leave a large dish of water under my tomatoe plant and let the roots take water as it needs it. This I would use instead of a soaker hose. Also, I have an orange bell pepper, I would like to do the same with. What about planting tomatoes in those hanging upside down containers.

Kelly Smith

Hi Jeanie,

Many of the plant roots are near the surface of the container, so it’s important to keep the soil moist at the top. If you’re using a large container and only watering from below, I’d be concerned that the plant wouldn’t be getting the water where it needs it most. So I suggest a soaker hose if you can swing it! Read our article on watering pots for more info.

The upside down containers are really popular. Make sure you place them where they get enough sunlight, and I’d also suggest that you choose a determinate tomato.

Happy growing!
Kelly, Bonnie Plants

JAYMZ HUTMIRE

SHOULD I WATER MY TOMATOES DAILY? I PLANTED THEM ON THE 12TH AND HAVE WATERED THEM DAILY THUS FAR. I LIVE IN THE CHICAGOLAND AREA.

Kelly Smith

Hi Jaymz,

I suggest you read our article “How Much Water Do Vegetables Need?” You might want to get a rain/water gauge to measure how much water your plants are getting. You can also read the other articles in our Watering section to learn more best practices.

Happy growing (and watering)!
Kelly, Bonnie Plants

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