How Much Water Do Tomato Plants Need?

If you want mountains of juicy and delicious tomatoes season after season, watering is one of the most important tasks to get right. Unfortunately, many new gardeners struggle to manage their watering schedule, increasing the risks of underwatering and overwatering.

However, it’s not complicated once you understand the needs of tomato plants and how the environment plays a role. These tips will help you water your tomatoes at the perfect time, eliminating the stress and allowing you to focus on enjoying your harvest.

How Often to Water Tomato Plants

Before deciding how much water your tomato plants need, start with how often to water. You may find it easier to work on a schedule (watering every three days, for example). But this ignores changes in growth, weather, and planting environment that can impact how much water your plants need.

Instead, assessing the plant and environmental conditions and checking the soil before you water is best. This avoids any potential issues with under or overwatering that may impact your harvest.

These are the factors to look out for that influence how often to water and how you can use them to get your timing perfect:

Stage of Growth

Soon after planting your tomatoes, keeping the soil consistently moist is vital. The initially shallow root system will need frequent moisture to encourage growth deeper into the soil, creating a more robust plant capable of handling drier conditions later on.

Once the deep root system is established, you can water slightly less often. The roots will access moisture in the lower soil layers, meaning they stay hydrated even if the top layer dries out.

Still, tomatoes need regular watering to fuel leaf and stem growth. As long as you water slowly and deeply, you won’t need to water as often.

Provide the most care when your tomato fruits start to mature. Infrequent watering at this stage can stunt development or cause fruits to crack. Watering slightly less can help prevent cracking (and may improve overall flavor), but you don’t want to go to the extreme of underwatering and risk the fruits dropping off early.

Although this balance sounds complex, it’s not difficult to manage if you check the soil regularly and get your hands dirty. Knowing how much moisture is present in the soil will help you decide whether it’s time to water again or not.

Weather

Temperature has a massive impact on moisture levels in the soil and, by extension, how often you need to water. Higher temperatures and intense sunlight translate to an increase in watering schedule, while dips in temperature keep the soil moist for longer.

Temperature also influences how much water the plant absorbs. The roots absorb more moisture to fuel growth in the warm weather these plants prefer. When temperatures drop below around 50°F, growth slows dramatically, and your tomatoes need less water.

Humidity impacts watering, albeit to a lesser extent. Dry air and warm temperatures will cause moisture in the soil to evaporate quicker than in high-humidity areas.

Finally, if your tomatoes are exposed to the elements, consider rainfall too. This one explains itself – if it’s rained recently, your tomatoes won’t need much additional water.

In-Ground vs. Containers

Due to their size, gardeners typically grow tomatoes directly in the ground or raised beds. However, tons of compact varieties like ‘Patio Choice’ (usually the determinate tomatoes) are ideal for growing in pots.

While containers have the advantage of smaller size and portability, they dry out much quicker than tomatoes in the ground. Not only is there less soil to hold onto the moisture, but the sides of the container are also exposed to the sun, causing the soil to dry out faster.

While tomatoes in the ground may need water every three or four days on average, your potted tomatoes will likely need to be watered almost daily, especially in the middle of summer.

How Much Water Tomato Plants Need

The general advice from horticulture experts is to give your tomato plants about an inch of water per week – the same as most garden plants. Since they are slightly more thirsty than other edible plants, you may want to increase this to two or three inches of water per week in warmer regions.

Unfortunately, it can be hard to translate this somewhat abstract amount into an actual watering schedule, considering all other factors.

Rather than thinking in inches, it’s best to focus on checking the soil regularly and watering when it begins to dry out, depending on conditions. Stick your finger or hand deep in the soil to feel the moisture at varying depths. You can also watch for signs your tomatoes need water, although the soil is usually quite dry when they display symptoms like wilting.

When you do water, make sure you water deeply to reach the layers of soil lower down. Shallow watering won’t cover all the roots and can lead to confusion when you spot things like wilting and blossom drop despite watering frequently.

Signs To Water Your Tomatoes

If you forget to check the soil regularly or haven’t watered in a while, your tomato plants will quickly tell you they are thirsty through a few classic signs.

The first and most obvious one to look out for is wilting. Leaves wilt when the cells lack moisture, unable to hold their upright structure. In intense heat, leaves generally wilt in the middle of the day. But it’s time to water if they wilt continuously during moderate temperatures.

Tomatoes that have been underwatered for longer periods will begin to show more dramatic signs of stress. Yellowing leaves from the base of the plant or weak stems that cannot hold themselves up can be caused by other factors but are often the result of a lack of moisture. You may also have problems with blossom drop or general lack of growth.

Going to the other extreme and watering too often is also possible. These thirsty plants are still at risk of root rot if you water when the soil is saturated if the soil does not drain well enough, or if there is excessive rain in your region.

Since either extreme is dangerous and can potentially ruin your harvest, it’s vital to strike a balance and water when your tomatoes need it.

Tips For Watering Tomato Plants

Along with providing the right amount of water at the right time, there are a few other tips that can help you master tomato plant watering:

Water Slowly and Deeply

To develop a strong root system, it’s essential to water slowly and deeply from the start of growth.

Tomato roots will spread where the moisture is, so watering deeply will encourage them to send their roots deeper into the soil. This creates a stronger plant more capable of handling dry spells.

Shallow watering will result in a shallow root system. Not only does this mean you’ll need to water more often, but growth above the soil line will also be less vigorous and more prone to uprooting with a strong gust of wind.

Use Mulch

Mulch comes with a ton of benefits in the garden. But when it comes to watering, the main benefit is moisture retention. A thick layer of mulch limits evaporation and regulates soil temperatures, keeping the roots satisfied for longer.

Along with moisture retention, organic mulch keeps weeds down and can improve soil quality as it breaks down gradually.

Water at Soil Level

Whenever you water your tomatoes, ensure you focus the stream of water on the soil, avoiding the leaves.

Tomatoes are prone to several diseases, far more likely when watering overhead. Focusing on the soil also ensures all the moisture reaches the roots where needed rather than evaporating away, saving your water bill in the long run.

If you struggle to water the soil directly due to limited access or have consistent problems with fungal diseases like powdery mildew, drip irrigation can help prevent the problem and take the stress out of the watering process.

Water In The Morning

Even if you’re not a morning person, it’s worth getting up a little earlier to water your tomatoes at the perfect time.

Watering in the morning ensures the roots can draw up enough moisture to withstand the day’s heat. It also allows any excess that does fall on the leaves to evaporate off, preventing disease. Morning or evening temperatures will ensure the roots absorb moisture before that moisture evaporates, also saving water.

Check Plants Often

The key to watering at the right time is monitoring your plants carefully. Check the soil daily – especially in the middle of summer – and also use the opportunity to look for signs of stress or disease to keep your plants at their happiest.