Watering Tomatoes Correctly

How to Water Tomato Plants Correctly

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Tomato plants require consistent watering for healthy growth and maximum yield. Paying attention to soil moisture and stages of growth ensures your tomato plants receive the right amount of water – at the right time.

Determining Soil Moisture

So how do you know when to water your toms? There are a couple of easy methods you can use.

  1. Finger Test: Insert your finger into the soil up to the second knuckle. If the soil feels dry at that depth, it’s an indication that watering is necessary. If it feels moist, you can delay watering.
  2. Moisture meter: You can get simple meters that you place in the soil and they monitor the moisture level. I have used this one, and it works well.

Tomatoes can be fussy plants when it comes to water, they don’t like too much when they are young, but if you are inconsistent with your watering with older plants, then you can end up with problems like blossom end rot.

That brings me nicely to my next point.

Stages of Growth

The water requirements of tomato plants change as they grow.

  • Seedlings: For young tomato plants, avoid soaking the soil but also ensure the soil doesn’t dry out completely. Seedlings require carefully controlled moisture to aid in root development.
  • Vegetative growth: As the plants grow larger, increase the amount of water to support their growth. Consistency in watering is crucial during this stage to avoid issues like blossom end rot and cracked fruit.
  • Fruiting: Tomato plants will need even more water during the fruiting stage, as the plants dedicate more energy to producing fruit.

You can also completely stop watering your tomato plants in their last few weeks of life. This helps intensify the flavour of the last few fruits on the plant.

Best Techniques for Watering Tomatoes

Watering tomato plants can be tricky, but using the proper techniques can ensure a healthy and bountiful harvest. This section will focus on three effective methods: drip irrigation, hand watering, and mulching.

Water The Base

No matter what method of watering you choose, it is important to water the base of the plant rather than the leaves.

Watering the leaves can cause disease problems and leaf burn if not done in the early morning or evening.

Drip Irrigation

Drip irrigation is a highly efficient method for watering tomato plants. It uses a system of tubes and emitters to deliver water directly to the plant’s root zone, minimising evaporation and runoff.

This method can save water, encourage deep root growth, and reduce the risk of diseases caused by wet foliage – but it is time-consuming and expensive to set up. When using drip irrigation:

  • Install a timer to automate watering schedules.
  • Space emitters 30-45cm apart for adequate coverage
  • Adjust the watering frequency based on your soil type and weather conditions.
  • Monitor soil moisture regularly to prevent over-watering or under-watering
Drip Irrigation System
Drip Irrigation System

You can also make your own drip irrigation system by puncturing some holes in a hose. Run this around the base of your tomato plants, then connect it up and turn on the water whenever it is time to give those toms some H2O!


Mulching can conserve soil moisture and regulate the temperature around the tomato plants. Applying a layer of organic material, like straw, compost, or grass clippings, around the base of the plants can:

  • Reduce water evaporation from the soil surface.
  • Maintain consistent soil moisture levels, preventing blossom-end rot and irregular fruit development.
  • Suppress weed growth, reducing competition for water and nutrients.
  • Insulate the soil, keeping roots cool and moist during hot weather

For best results, apply a 5-10cm layer of mulch around the tomato plants, avoiding direct contact with the plant stems. Replace or replenish the mulch as needed throughout the growing season.

Grass is a great mulch to use as it also provides nitrogen to your soil. If slugs are a problem though, grass can be a nightmare as it gives the slugs a great place to live.

When to Water Tomato Plants

Time of Day

It is best to water tomato plants in the early morning. Watering in the morning allows the plants to absorb the moisture before the day’s heat sets in, reducing the risk of water evaporation and ensuring that the plant receives an adequate water supply.

Watering during the morning or evening minimises the chances of sunscald on the leaves or blooms of the plant, as the sun’s rays are not as intense.

Signs of Overwatering

One common issue that can lead to poor tomato plant health is overwatering. To prevent damage, be aware of the following warning signs:

  • Yellowing leaves: Excessive water can cause lower leaves to turn yellow and fall off the plant.
  • Wilting despite wet soil: Overwatered tomato plants might exhibit wilting, even when the soil feels damp to the touch.
  • Root rot: As a result of prolonged overwatering, the roots can become infected with fungi and begin to rot. This might cause the entire plant to exhibit wilting, leading to eventual plant death.
  • Cracked fruits: Tomato fruits that receive too much water are prone to cracking, a sign that their skin can’t accommodate the excess moisture.

Signs of Underwatering

On the other hand, insufficient water can also hinder tomato plant health. Keep an eye out for these indications that your tomato plants need more water:

  • Drooping leaves: Tomato plant leaves can become limp or droop if they don’t receive adequate water, especially during hot weather.
  • Dry soil: If the soil around your tomato plants feels dry to the touch, your plants might need more frequent watering.
  • Stunted growth: Underwatered tomato plants may not grow as quickly or produce as many fruits as they should.
  • Blossom end rot: When tomato plants lack proper hydration, they can develop blossom end rot, characterised by dark, sunken spots at the fruit’s base.

Common Watering Mistakes

Inconsistent Watering

One of the most common mistakes gardeners make is inconsistent watering. Tomato plants require a steady supply of water to thrive and produce a healthy harvest.

It is essential to provide them with even and regular moisture, preventing the soil from becoming too dry or too wet. Inconsistent watering can lead to various issues, such as:

  • Cracked fruit: When the plant receives irregular water, the tomatoes can develop cracks or splits.
  • Blossom end rot: This is a calcium deficiency issue that arises when watering is inconsistent, causing the bottom of the tomatoes to rot.
  • Stunted growth: The inability to provide proper watering can prevent the plant from achieving its full potential, reducing the quality and quantity of the harvest.

To avoid these watering-related issues, monitor the soil moisture and provide 1 to 2 inches of water per week.

Overhead Watering

Another common mistake in tomato growing is overhead watering. While it may seem convenient, it can be detrimental to your tomato plants.

Watering tomatoes from overhead can cause several issues, such as:

  • Spreading diseases: Wet foliage can create an environment that encourages the growth of mould and fungus, which can spread diseases like blight, leaf spot, and others.
  • Sun scald: Overhead watering during the hot hours of the day can cause water droplets to act like magnifying glasses, intensifying the sun’s rays and burning the leaves and fruits.

Instead of using overhead watering methods, use drip irrigation or water at the base of the plant to keep the leaves dry.

This approach will help protect your tomato crop from common issues and ensure a healthy, bountiful harvest.

Additional Tips to Maximise Tomato Yield

1. Select high-yielding varieties: Start by choosing tomato varieties that are known for their high yields. Research different types of tomatoes and pick the ones that are well-suited to your climate and growing conditions.

2. Prepare the soil: Tomatoes thrive in well-draining soil that is rich in organic matter. Before planting, amend the soil with compost or other organic materials to improve its structure and fertility.

3. Space plants well: Ensure that each tomato plant has adequate space to grow. Proper spacing allows for good air circulation, which can help prevent diseases and promote healthy growth. Follow the recommended spacing guidelines for the specific variety you are planting.

4. Provide plenty of sunlight: Tomato plants need a minimum of 6 to 8 hours of direct sunlight per day for optimal growth and fruit production. Position your plants in an area where they will receive full exposure to sunlight throughout the day.

5. Water consistently: Tomato plants require 1 to 2 inches of water per week. Consistent watering helps to prevent issues like fruit cracking or blossom end rot. Be sure to water the plants deeply and regularly, especially during hot weather or periods of drought.

6. Prune and stake plants: Prune your tomato plants to remove any unnecessary growth, such as suckers, which can divert energy away from fruit production. Staking your plants helps to support their growth and allows for easier maintenance.

7. Control flower and fruit drop: Keep an eye on your tomato plants for signs of flower or fruit drop, which can reduce the overall yield. Address potential issues such as temperature fluctuations, pests, and nutrient deficiencies to ensure healthy growth.

By following these guidelines, you can help maximise the yield of your tomato plants, resulting in a more bountiful harvest.

Frequently Asked Questions

How much water do tomato plants need daily?

Tomato plants require 1 to 2 inches of water per week. This can be adjusted based on factors such as climate, rainfall, soil conditions, and the plant’s stage of growth. It is crucial to maintain consistent and deep watering to ensure healthy growth and a bountiful harvest.

When should I stop watering tomatoes?

As the final fruits begin to ripen, it is recommended to reduce the amount of water given to the tomato plants. This helps encourage sugar production and results in sweeter, more flavourful tomatoes.

What are the best DIY tomato watering systems?

One effective DIY tomato watering system is the drip irrigation method, which delivers water slowly and consistently to the root zone. This can be achieved by using a perforated hose or soaker hose placed around the base of the plant. Another option is creating a self-watering container, allowing the tomato plant to absorb water as needed from a reservoir below.

Can overwatering harm tomato plants?

Yes, overwatering can be detrimental to tomato plants. Excessive water can cause roots to become waterlogged and lead to problems such as root rot, reduced oxygen levels, and nutrient deficiencies. While tomatoes require ample water, it is important not to overdo it.

How often should potted tomatoes be watered?

Potted tomato plants usually require more frequent watering than those planted in the ground. They typically need to be watered twice as much, approximately 2 to 3 inches of water per week. Factors such as container size, soil type, and environmental conditions can influence the exact watering frequency.

What is the watering frequency for tomatoes during hot weather?

During hot weather, tomato plants may require more frequent watering to compensate for the increased evaporation. Monitor the soil moisture and adjust the watering schedule accordingly. It is essential to maintain consistent soil moisture and water more often, while avoiding overwatering, to ensure the health and productivity of the tomato plants.

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