“What Are Some Basics I Need to Know About Watering Tomato Plants?”

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Updated 6.10.24

Watering tomato plants: the basics you need to know with Tomato Dirt #HomeGarden #BegetableGardening #BeginnerGardening

When you understand what tomatoes use water for, then it setting up a tomato watering schedule makes sense.

Why tomatoes need water
(in plain English)

Tomatoes are fast-growing, heavy-producing plants. They make a lot of food (sugars) in order to grow blossoms, develop fruit, and put out more branches. It takes a considerable amount of water to convert sunlight into energy for a tomato’s many branches and blossoms.

Here’s a quick review from high school biology class about what happens with water in a tomato plant. You can see why water is incredibly important to growing healthy tomatoes.

plants absorb water through their roots
water finds it way up the plant to the leaves
some water is used in the leaves to make food (sugars) for the plant. This process is called photosynthesis, and it’s responsible for converting sunlight into energy for your tomato.
some water is released through the leaves to cool them. This process is called transpiration. It’s based on the same principle as perspiration in people.

As a gardener, watering is one factor that you can control!

Top 3 keys to watering tomato plants

It’s simple when you know when, where and how to water them.

WHEN

Water regularly. Consistent watering produces stronger plants and larger fruit. In the height of summer, water 2-3 times a week. (Rainfall counts.) Later when temperatures cool, scale back to once a week.

WHERE

Water at the soil line. You’ll help build your tomato’s root system. Avoid overhead watering, which spreads diseases. That goes for watering tomatoes in pots, too.

HOW

Water slowly. Let water sink into the ground to help plants develop strong root systems. When the soil surrounding your tomato plant is moistened 6-8” deep, you’ll know you’ve done your job well. Try different tomato watering techniques to see what works for your garden.

Drip irrigation is one of the most effective ways to water tomatoes. You an use soaker hoses (also called drip hoses) which you can modify easily to fit your garden. Or do one better and install a drip irrigation system. They're not expensive -- and you will have watering set up for a whole season. You can use a water timer to make watering even more consistent and convenient.

Tomato problems that arise with improper watering

Tomato Problem	Causes
blossom-end rot	calcium imbalance caused by irregular watering: over watering followed by under-watering means calcium can’t be absorbed consistently into tomato
cracks, splits in fruit	irregular watering, over watering after drought: leads tomato skins to expand, contract, and split
small fruit, stunted growth, reduced production	irregular watering, under-watering: to stay cool, plants limit the exchange of oxygen and carbon dioxide through leaves, which slows growth
susceptibility to tomato fungus	overhead watering or watering at night, which allows fungi to rest on the leaves
tomato root rot, root loss	overwatering: soggy soil prevents roots from getting oxygen light watering, sprinkling: roots reach to the surface in search of water