How to grow Tomatoes

How to grow Tomatoes - Introduction

An outdoor crop ripening in the summer sun
  • While technically a fruit, most people consider tomatoes to be an essential part of the vegetable garden. 
  • Greenhouses and polytunnels offer the best conditions in the UK for producing a summer-long feast of tomatoes. 
  • However, outdoor ripened fruit can be worth waiting for as they have a different taste to the indoor grown plants.
  • Tomatoes take about 12 weeks to grow from seeds to the blossom stage, and another 8 weeks to produce ripe fruit.  
    • This is the reason we don’t see ripe tomatoes outdoors until the end of July or early August.
    • By starting plants in the winter months in heated greenhouses or poly-tunnels, it is possible to bring the fruiting season forward by 4 - 6 weeks.
  • There are varieties suited to growing indoors and outdoors and some bred especially for containers and hanging baskets. 
  • Whichever variety you choose, all need fertile soil, and plenty of regular sun, heat, food and water to produce sweet, juicy fruits.
  • You have two options for acquiring tomato plants. 
    • Your first option is to grow your plants from seed. If you select this option then you will need to start your plants in a greenhouse or in your home, and then transplant the tomato plants to you garden in April or May.  see the section below for detailed facts.
    • If you don’t want to invest this much time in your tomatoes you can always buy tomato plants from a nursery or garden center.
  • When you shop for a tomato plant you will want to look for a healthy plant. 
    • Examine the leaves.
    • Healthy plants won’t have spotty leaves or yellow leaves. 
    • You will also want to look for a plant that is naturally resistant to certain disease strains. The tag on the plant will have letters that tell you what they are resistant to. A key to these letters should be provided on the container or in a sign posted near the tomato plants.
  • It is safe to plant tomatoes in the garden when the temperature is a consistent 10°C (50°F), but plants won't begin to set fruit until the overnight low is regularly above 13°C (55°F). 

How to grow Tomatoes - Site & Soil

  • Tomato plants, like any plant that produces fruit, need at least seven hours of direct sun. 
    • If you have less, you will have fantastic foliage but very few fruit. 
    • There is nothing at all that can overcome this light requirement. 
    • Fruit production takes a tremendous amount of energy, and tomato plants, like all plants, get that energy from the sun.
  • Use the best soil available to grow the tomato crop. 
    • Clay and sandy soils can be improved by working in 2 to 3 inches of compost, peatmoss, or other forms of organic matter in the top 6 to 9 inches of soil. 
  • Lime and fertilizer should be added according to soil test recommendations. 
    • If no soil test has been taken, apply 3/4 cup of lime and 1/2 cup of 8-8-8 fertilizer for each plant. 
    • Lime will help reduce nutrient imbalances, particularly with calcium and help control the blossom end rot problem that occurs so frequently on tomatoes.
  • The exacting conditions detailed above are the reason why so many people prefer to simply grow their tomatoes in growbags. 
    • A growbag is a large plastic bag filled with peat or a similar growth medium. 
    • The bag contains enough nutrient for one year's growing and requires only planting and watering. Treat the nutrient claim with some scepticism, as tomatoes are greedy feeders.

How to grow Tomatoes - Sowing Seed

  • Fill a 7.5cm (3in) pot with compost, lightly firm and water.
  • Scatter seeds thinly (most germinate so only sow a few more than you need) and cover with a thin layer of vermiculite.
  • Label and put on a windowsill to germinate. 
  • Seedlings should appear within two weeks and be large enough to move into separate pots in about eight weeks.
  • To pot-on, hold seedlings carefully by their leaves and gently lever up with a dibber. 
  • Make a hole in a 7.5cm (3in) pot filled with compost and carefully lower in the seedling.
  • Gently firm, making sure roots are covered and water. 
  • When roots come through the drainage holes put into a 12.5cm (5in) pot.
  • When the first truss or 'branch' of flowers has appeared, tomatoes are ready to be planted out, whether it be outdoors in soil, or growbags, or in greenhouses and poly-tunnels in soil, pots or growbags.

How to grow Tomatoes - Planting Out

  • Avoid transplanting during the heat of the day. 
    • You want as little stress as possible on the plants, and their roots will have been disturbed, so choose early morning or evening to give the plants time to adjust. 
  • Handle carefully. Remember that the fine hairs all along the plant stem can become roots if they are not damaged. 
  • Plant deep, leaving only 2-3” of stem above ground, and the fine hairs will become roots which will ensure strong growth.
  • If the transplant is tall and leggy at time of planting, the trench planting method should be used. 
    • To trench plant a tomato plant, dig a horizontal trench rather than a hole for each plant. 
    • Next, remove all of the leaves from the plant except the top leaf cluster (4 to 5 leaves). 
    • Then lay the plant on its side in the trench and cover the root system and bare stem up to the top leaf cluster with 2 to 3 inches of soil. 
    • Firm the soil over the plant. 
    • Be sure not to press the soil too firmly around the stem where it comes out of the soil, as the stem may break.
  • Don't plant them too close.
    • Tomato plants need at least 50cm (1 1/2 feet) between plants, preferably 65cm (2 feet), and that's for plants that are grown upright on stakes or cages. 
    • If no support is given and they are allowed to sprawl on the ground, tomato plants need twice as much room. 
    • Plants spaced too closely will produce few fruit and have more disease problems as the foliage stays wet. 
    • Plant according to how big they will get, not on the size of the transplants.
  • Planting in growing bags requires a slightly different approach to planting out in garden soil.
    • Prepare the bag by shaking and kneading it to break up clods of compacted compost and form into a hummock shape.
    • Puncture the base to make some drainage holes and cut out the pre-marked planting squares. Scoop out compost for the tomatoes to be planted.
    • The top of the root ball should be beneath the top of the bag and have a light covering of compost. Firm in and water.
    • Put a growing bag frame over the bag and insert a cane next to each plant.
    • Secure this to the frame and as it grows, tie the tomato to the cane every 10cm (4in).
  • Water well after planting and ensure that the soil never becomes dry.

How to grow Tomatoes - Care & Cultivation

  • You need to consider supporting all tomato plants, except for tumbler varieties.
    • As tomato plants mature, they begin to sprawl along the ground because they become heavy with fruit. 
    • If left to grow without training, the fruit is exposed to sunscald and inclined to rot. 
    • An effective way to prevent these problems is to train the plants to grow vertically by staking the plants.  Tie the stem to the stake at 15cm (6 inch) intervals.
    • Another simple training method is to build tomato cages. As the vine grows, guide the stems into the cage.  

Tomato Support

Tomato Stakes

  • Generally, staking produces larger tomatoes but less quantity than caging. 
  • A common 2 metre (6 foot) tomato stake may be purchased from many garden centres. 
  • The stake should be driven in the soil about one ft deep, 7 to 12 cm (3 to 5 inches) from the plant. 
  • Be sure to avoid driving the stake on the root side of plants that have been trench planted. 
  • Trench planted tomatoes should be staked immediately after planting while the location of the buried stem is fresh in mind. 
  • Use a strip of cloth, nylon stocking, or heavy string to tie the plant to the stake.

Tomato Cages

  • Tomato cages produce most fruit.
  • Tomato cages may be made by using a 1.75 metres (5½ foot) length of concrete reinforcing wire or pasture wire. 
  • The wire will form a circle 50 cm (18 to 20 inches) in diameter. 
  • Fencing wire is not suitable, as the holes are too small to enter a hand and remove grown fruit.
  • The bottom horizontal ring of the wire cage should be cut off so that the ends can be pushed into the ground. 
  • After setting the cage in place over the tomato plant, drive 2 or 3 stakes around the outside edge of the cage to give it extra support.

Tomato Pruning

  • Unless you're growing a bush tomato, the aim is to create a single-stemmed plant.
    • To do this, snap out shoots that grow in leaf joints and when your plant has produced four good sets of flowering trusses, pinch out the growing tip.
    • This will ensure all its energy goes into producing fruit. 
  • Remove all leaves that are touching the ground because of the accessibility to bugs and disease, as well as moisture-related problems .

Tomato Watering

  • Water plants daily and once flowers have started to appear, feed with tomato fertiliser every week to ensure the best fruit.
  • When the soil around tomato plants is allowed to dry out, a serious problem results. 
  • Calcium, one of the handful of minerals needed by all plants to grow, is absorbed by the plant's roots along with water. 
  • If water is limited, so is calcium. 
    • The result is blossom-end rot, a brown, dry, leathery spot found on the bottom of fruit. 
    • Don't be fooled by magic remedies that promise to fix this. 
    • Special fertilizers, egg shells or a Tums tablet placed next to the plant won't make a difference. 
    • Only water will make the difference. 
  • So make sure your soils don't dry out and use mulch to help conserve moisture.

Tomato Feeding

  • Feed the plants, but not too much
    • Tomatoes like a balanced fertilizer, with similar amounts of nitrogen, phosphorus and potassium. 
    • Avoid using fertilizers that are intended for lawns. The high nitrogen will push the leaves at the expense of fruit. 
    • Look for fertilizers designed for tomatoes and follow the label directions. 
    • Or better yet, throw a shovel full of compost around the plants every other week.

How to grow Tomatoes - Baskets and Pots

  • Line a 13in basket with a polythene-backed sisal and jute liner. 
  • Mix a water-retaining product (Chempak Supergel and Phostrogen Swellgel are current Which? Best Buys) and a slow-release fertiliser (Westland Feed-all Slow Release Plant Food and Phostrogen Slow Release Plant Food Granules are current Best Buys) into the compost before filling your basket. This will help reduce the need to water and feed the plants.
  • Sit the basket on a bucket or flower pot to keep it stable and fill with compost. Avoid using John Innes compost as this will make the basket very heavy. Don't fill to the brim as you need to allow room for watering.
  • Place a tomato plant in the centre of the basket (sow seed undercover in April or buy young plants in May or June), firm in and water in well.
  • Keep your basket in a frost-free place until all risk has passed, then hang in a sunny, sheltered position.
  • Keep your basket well watered to avoid split fruit. This may mean watering twice a day in hot weather.

How to grow Tomatoes - Harvesting

  • If you find yourself with a glut of green tomatoes at the end of the growing season, try putting a few in a kitchen drawer with a banana to encourage them to ripen.

How to grow Tomatoes - Store & Preserve

  • Fruit that is fully ripened on the vine has a much fuller flavour than fruits that are picked early and then allowed to ripen. 
    • Many cherry tomatoes, however, have a tendency to crack if they stay on the plant, so they should be picked at the peak of redness, or even just before.
    • When daytime autumn temperatures are consistently below 16°C (60°F), fruit will no longer ripen on the vine, so it is time to bring all mature green fruits indoors, either on the vine or off.
  • Storing ripe fruit.
    • Wash and dry your tomatoes before storing. 
    • Unless you're planning to store your tomatoes for over a week, a windowsill, counter-top or bowl works fine. 
    • If you know you won't use them in the next few days, then lower temperatures (a cool entryway, the refrigerator) will help preserve the fruit. 
    • Contrary to common practice, storing in a refrigerator is not otherwise recommended, as the cooler temperatures can reduce flavour and cause mushiness. 
    • Your fresh-picked tomatoes will last longer on the kitchen counter than store-bought ones, which are probably a few days past picking when you get them.
  • If you end up with too many tomatoes to eat at one time, try these storage methods:
    1. Canning, which will preserve your tomatoes for a year or more.
    2. Freezing, which can be used for up to eight months.
    3. Drying, which can keep tomatoes for more than a year.
      • Ripening green fruit is a topic that causes controversy.
        • Most of us grew up placing unripe tomatoes on a sunny windowsill -- with the emphasis on sunny. 
        • However, every expert source recommends placing them in a paper bag. Light, so essential to growth and to setting fruit, is not needed to ripen the fruit. Hence, the dark place. 
        • While light is unnecessary, humidity and temperature control are critical during ripening. Tomatoes kept on a counter-top can become too dry, while those in a plastic bag can mould or ferment. Hence the paper bag. 
        • Temperature is also important, and the paper bag acts as a miniature greenhouse, trapping some of the day's heat. 
        • There's another advantage to the bag. Tomatoes, like most fruit, emit ethylene gas as they ripen. This gas is a by-product of ripening, and is also a stimulant for ripening. 
        • When you store unripe tomatoes in a bag, the ethylene emitted by the riper ones will stimulate the others to ripen. 
        • Since most fruits emit ethylene, you can use another, ripe fruit to hasten the ripening process. Bananas work especially well because they emit more ethylene than most fruits.
        • If the bag doesn't appeal to you, remember that one of the best sources of heat is still the sun and the sunny windowsill. 
        • If you turn them daily, rotting is unlikely, the light may not be helpful, but it doesn't hurt, and the humidity control is not much of an issue with nearly-ripe fruit.
      • If it's the end of the season, and you're dealing with quantities of green tomatoes still on the vine, the time-honoured method of ripening tomatoes indoors is to cut the vines and hang them intact, upside down, in a dark place. 
        • Believe it or not, most of these tomatoes will indeed ripen. 
        • Those picked when their outer color changes to a lighter, more translucent shade of green known as mature green will fare better than those that are still a dark green. 
        • These very unripe fruit are candidates for other uses.
      • You can find recipes for chutney, pickles, and even pie made from green tomatoes.