Tomato Dirt answers your questions about watering tomatoes.
Q. How much should I water a newly-planted tomato?
A. A quart of water a day (more if temperatures are hot, if there’s significant wind, or if it’s especially sunny with little cloud cover) for the first 7-10 days. Learn more about watering newly-planted tomatoes.
Q. What about early in the season?
A. For tomatoes that have been in the ground for 10-14 days, water 1-to-3 inches over 10 days or even 2 weeks. The touch of extra stress on the plant pushes it to produce fruit. When tomatoes emerge and are about the size of a quarter, resume your routine of watering tomatoes 1-to-3 inches a week. Once fruit is set it’s very important to keep your watering pattern consistent.
Monitor how much rain your tomatoes get with a rain gauge. Use a water usage meter to track how much water you're giving plants. Check soil moisture with a soil moisture meter.
Q. How much water do my established tomatoes need?
A. Tomatoes, like most veggies in the garden, need an inch of water a week and up to 3 inches if it’s particularly hot. (That includes rainfall). Follow the 1-to-3 inches a week rule during the main growing season, once tomatoes have been in the ground longer than 2 weeks. When it’s particularly hot, make that 1.5 inches. In the height of summer, water 2-3 times a week, but maintain consistent amounts.
Q. Do my tomato plants need 1-3 inches of water a week even towards the end of the season?
A. Yes. When temperatures cool, scale back frequency – watering tomatoes just once a week – but make sure plants get 1-3 inches a week.
Q. What’s a quick way to know that my tomatoes need water?
A. If the soil next to your tomato plant is dry an inch below the surface, get out the hose. (Drip hoses work really well. You can set them up on a water timer to make watering even more consistent and convenient.)
Q. I have sandy soil. Should I water my tomatoes differently?
A. Water seeps through sandy soil faster than loam or clay. Double the Inch-A-Week rule but water consistently – 2-3 times a week during the main growing season. Beware that your soil may leach nutrients quicker than other soil types, which may require you to adjust your fertilizing schedule. Add organic matter to your soil to help it retain moisture better.
Q. My soil has high clay content. What can I expect when I water my tomatoes?
A. Expect water to pool. Clay soil binds tightly, making it difficult for water to penetrate deeply. Runoff is a problem. Water slowly to maximize absorption, and improve your soil by adding organic matter.
Q. I live in a hot (or dry) part of the country. Is one inch of water a week enough?
A. Probably not. Double the Inch-A-Week rule but water consistently – 2-3 times a week during the main growing season. Likewise if your area is in a drought.
Q. Why is it important to water tomatoes slowly and deeply?
A. Deep watering forces roots to burrow lower into the soil to get water. That helps your plant build a strong root system, which in turn allows it to withstand the stresses of hot or dry weather. Light surface watering guides the roots towards the soil, where they’re more easily damaged and susceptible to drought and exposure. Best advice: watering tomatoes slowly and deeply prevents tomato problems. (One of the best ways to water slowly and deeply is to set out drip hoses on a water timer.)
Q. What’s the best time of day to water my tomatoes?
A. The gardening jury is out on this one.
Early morning watering advocates like to give their tomatoes a drink a way of fortifying them for a full day of leaf, flower, and fruit production when the sun is high in the sky. Also, watering tomatoes early in the day cuts down on evaporation, so plants stay hydrated longer.
Some gardeners make a strong case for watering in the middle of the day. Midday heat and sun help leaves dry quickly, which increases humidity around plants and cools the leaves. Cooler leaves = less water loss through leaves = less midday wilting. Still other gardeners claim that drip watering all but eliminates water splashing on leaves and can be successful any time of day.
Q. What’s the worst time of day to water my tomatoes?
A. Gardeners agree hands down: the worst time of day to water is evening. Water has a greater chance of remaining on your tomato’s leaves when the air gets cooler at night. If leaves are wet for longer than 3 hours, they become prime targets for leaf-blighting and leaf-spotting fungi. Try to steer clear of those nasties. Water your tomatoes during the day.
Q. Why is over watering unhealthy for my tomatoes?
A. Soggy soil chokes your tomato’s roots and prevents them from getting oxygen. Bottom line, over watering drowns your tomatoes.
Q. My tomato plants droop in the mid-afternoon. Is under-watering the problem?
A. Maybe. Your tomatoes may be healthy and simply reacting to the hot summer sun. If they perk up overnight, then stick to your watering schedule. If your tomatoes are still drooping in the morning, don’t wait – water them!
Wilting can also be a symptom of certain tomato problems.
Q. What can I do to help maintain healthy watering for my tomato plants?
A. Add organic matter to the soil. Maintain a consistent watering schedule. Also, mulch your tomato plants 3-5 weeks after planting to reduce evaporation. Learn more about mulching.
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