Every tomato you grow needs about three gallons of water. That translates to about 60 gallons of water per week, per 100-square-feet of garden. Tomatoes that don’t get enough or that get too much water can experience disease, rot or just end up malformed. Watering the soil, not the leaves, and adding mulch can help your tomatoes make the most of the water they get.
Give Your Tomatoes Enough Water
According to Fooducate, tomatoes are 94% water. It should be little surprise that they need an adequate amount of hydration to grow and thrive in the garden.
As this image from Business Insider shows, it takes a little over 3 gallons of water to produce one healthy, tasty tomato. What does that translate to when you’re actually watering your tomato plants?
A common recommendation is to give your plants about one inch of water per week during the growing season, usually from May through August. According to the National Gardening Association (NGA), gardeners in areas that are very hot or very dry are most likely going to need to give their tomatoes at least two inches of water per week.
“One inch of water” can be a confusing measurement. Luckily, the NGA provides a handy translation: one inch of water is about the same as 60 gallons of water for every 100-square-feet of garden. If you’re growing tomatoes in a 10-square-foot space, you’d need to give them about 6 gallons of water each week.
What Tomatoes Do With Water
Tomato plants need water to convert sunlight into energy to help it produce fruits and leaves. When you water your tomato plants, the plants take up the water from the soil through their roots.
The water then travels up the stems of the plants to the leaves. In the leaves, water plays a role in the process of photosynthesis, which turns the energy from the sun’s rays into sugar.
In case it’s been a long time since you took high school biology, the video above from Crash Course gives you a rapid refresh explaining how photosynthesis works.
Along with needing water for the process of photosynthesis, your tomatoes plants need it for some of the same reasons you do. Water helps the plants regulate their temperature. The leaves of the plant release water into the air, a process known as transpiration. It’s similar to perspiration, which people do to cool down on a hot day.
Problems from Too Little Water
Not getting the water they need can cause a number of problems for your tomatoes. In many cases, the problems develop in the fruit of the plants, causing them to crack or leading to a smaller than expected yield.
Blossom end rot is one common problem faced by tomato growers. You can tell if your tomatoes have it by looking at the bottom of the fruits. If you notice a leathery, brown spot on the bottom of the tomatoes, you’re dealing with blossom end rot.
The condition develops due to a calcium deficiency in the plant, according to the Alabama Cooperative Extension System. When tomatoes don’t get enough water, calcium can’t travel through the plant, causing the rotted area to form.
One of the best ways to handle blossom end rot is to cut the affected fruits off of the plant. You can eat them if they are ripe, just make sure to cut the brown, leathery area away. Leaving them on the plant can put it at greater risk for infection or make it more attractive o pests.
To keep the problem from recurring, increase the amount of water you give the plants. It’s also a good idea to make sure you are watering consistently.
Protecting Your Tomato Plants
You not only want to make sure you give your plants enough water. You also want to do what you can to keep that water from evaporating from the soil.
Adding a layer of mulch around the plants will prevent the soil from drying out very quickly on a hot summer’s day. The mulch can also help control weeds around your plants and can keep them from getting too hot.
You have a number of options when it comes to adding mulch. Some gardeners add a 3-inch layer of straw, others use a few inches of commercially prepared mulch.
In a video from eHow Garden, gardening expert Teca Thompson demonstrates how to add a layer of mulch around a small tomato plant. She uses a mix of newspaper and yard trimmings to add a protective layer around the plant.
It’s possible to give your tomatoes too much of a good thing. In some cases, excessive water might not be something you can control. If you have a lot of rain in your area, your tomatoes can suffer for it.
As Jeff Bernhard, the Executive Gardener explains in the video below, tomatoes that get too much water can experience root rot. When the soil is too wet, fungus is able to thrive.
The fungus infects the roots of the tomato, then travels up to the rest of plant. The leaves of the tomato plant will usually turn yellow and will eventually fall off.
Often, the best thing to do if your tomato plants have signs of root rot is to destroy the affected plants. Once it gets to the leaves of the plant, the fungus can easily spread to others in your garden.
Methods of Watering Tomatoes
You have several options when it comes to watering your tomato plants. If you only have one or two plants, the easiest way to water them might be to direct the spray of a hose at the soil near the plants for several minutes each day. Water the soil around the plants until it is saturated with water.
If you have more than two tomato plants, using a soaker hose, which has tiny holes up and down its length, can be the most efficient way to water your plants. Place the hose on the soil, turn on the water source and let it run while you work in the garden.
You might feel like Goldilocks when trying to find the right amount of water to give your plants, as you don’t want to give them too much or too little water. Pay attention to how your plants react, as they will usually let you know if it’s too much, too little, or just right.