Knowing your soil type will be useful in helping you learn how often to water. On average, you will most likely water twice a week. Sandy soil drains more quickly, so more frequent watering may be needed.
Take a sample of your soil to your local nursery to find out what kind it is, if you don't know. A soil moisture monitoring
probe is a useful tool to help you evaluate and adjust your watering scheme when you grow tomato plants. It is inexpensive and easy to use.
Just like people, plants are most healthy when they get the right amounts of the right kind of food. For tomatoes nutrition is obtained from the soil and mulch, and through fertilizer that you provide.
There are many fertilizers available that are marketed for growing tomatoes.
They need Nitrogen, Phosphorus, and Potassium (abbreviated as N, P, and K). You will see both chemical and organic fertilizers.
The organic type is best for tomatoes. If you have access to compost, that works well. Just toss some on top of the soil every two weeks.
To help the young tomato grow, the ratio should be equal. 6:6:6 and 10:10:10 are commonly found. Older plants, especially once they have started to flower, benefit from more phosphorus, such as
5:10:5.
Nitrogen helps leaves to grow lush and green. Too much can result in the overgrowth of leaves at the expense of fruit bearing.
Phosphorus promotes healthy roots. Potassium, also called potash, supports the development of flowers and fruit. Fruit that is too soft with poor skin condition can be the result of an overbalance of potassium.
Fertilizer granules should be covered with soil so that the nutrients penetrate better. They have the advantage of being longer lasting so you need to put them down less often.
Liquid fertilizers are mixed with water, so
they are more convenient, but you will need to apply more often.
A newer development is foliar fertilizers,
which are sprayed directly on to the leaves.
That needs to be done early in the day, before noon, when the leaves are most porous.
A soil test kit will enable you to keep track of
the amounts of N, P, and K as well as pH. Test
every week or so to make sure that there isn't too much or too little of anything.
Fertilizer may be applied either by sidedressing
or top-dressing. For side dressing, dig gently
around the plant to a depth of about one cm and put down the fertilizer.