Watering & Feeding Tomatoes

Watering and feeding tomato plants can be a tricky business – especially if grown in containers.

However, the minimum advice is just below and with a little extra knowledge (I’ve described what I think are the two most important factors), you can adjust amounts to suite your situation.

Watering
Compost or soil should be just moist and not too wet.
Feeding – only feed with tomato food when plants are beginning to fruit.

For watering, two main factors are:

• Temperature
• Size and Amount of Leaves

The warmer the day – the more water a plant needs. That’s just common sense, but also, take into account the amount of leaves there are.

A plant with few leaves will need less water than one that has a lot of leaves – like Tumbling Tom for example.

What happens if I over-water?
Roots need air as well as water so too much water will prevent roots (and plants) developing to their full potential.

Also, sitting in cold water is likely to make plants vulnerable to fungal diseases such as tomato blight.

How to water safely
Compost/soil should be just moist and plants in containers should not be sitting in a tray of water.

Of course it’s difficult keeping the soil just moist as on a hot day it will dry-out quickly. It is better to give a little extra to thoroughly soak the compost, then let it dry-out slowly.

Just before it becomes dry to the touch and the pot or container is much lighter in weight, give it another good watering.

The problem with giving a little and often is that water will always find the quickest escape route and that may leave patches or pockets of dry soil in containers beneath the surface.

Roots in dry soil cannot absorb water or nutrients. This can lead to Blossom End Rot which is caused by calcium deficiency. At such times a foliar feed may be necessary.

For feeding two factors are:

• Age of Plant
• State of Compost

It’s very easy to overfeed tomato    plants – especially when they are young. The problem with feeding young plants is that their roots are very sensitive and may be damaged if fed a solution of feed that is the same strength that an adult plant would have.

If you use good compost (already containing  food) there is very little need to feed until the plant is beginning to fruit – assuming that it has been potted-on with new compost every four weeks or so.

What happens if I overfeed?
The roots of young plants may be damaged and older plants may show signs of abnormal growth such as growing more leaves and fewer flowers than expected.

It is possible to block one nutrient by giving too much of another – so my motto is … if in doubt, don’t!

How to feed safely.
If you feed young plants, do so immediately after transplanting with just half the recommended dosage on the packet (that’s half strength).

Tomato plants, until they begin to fruit, should be fed with general purpose plant food (a balanced feed) as tomato food is mainly for the fruiting stage.

It’s very easy to become obsessed with feeding and how much should be given at  each stage of a plant’s growth. Generally, I try to avoid feeding until the fruiting stage … then I give them feed at every watering, but usually at a lower strength than recommended on the box – little and often is the secret.

If your tomato plants are in desperate need, foliar feeding is a good way to get the food in fast!

Be careful to check your box instructions because not all plant food is suitable for foliar feeding.

The above is a guide to how I water and feed my tomatoes. For a more thorough understanding of the subject, hydroponics offers a lot more detailed information of the minerals and nutrients that
tomato plants require.