The tomato plant requires a growing temperature of 60 F. In some of our cold, wet, summers especially the ones we frequently have in the North, the crops grown outside are often disappointing and can be attacked by potato blight disease.
Tomato plants can be purchased during May or you can raise your own from seed under glass. Those, which you intend to grow outside, must be one of the outside growing varieties to be successful.
Though seeds can be sown out-of-doors it is generally not a very satisfactory process unless they have shelter and warmth. If you purchase plants do make sure that they are well-hardened, sturdy, dark green specimens.
Tomatoes do not mind if the soil is light or heavy but it must contain plenty of organic manure. If you are growing the tomatoes outside they must be in a warm, sheltered position in a sunny aspect. In April add plenty of well-rotted compost or manure to the soil.
Sowing in the Greenhouse
The seed can be sown anytime between February and May they should be 2 in. apart in trays of seed compost covered with a sheet of glass until germination. Give as much light as possible, after about 28 days, pot up into 3 in. pots.
Planting Out in the Greenhouse
In the greenhouse, the plants may be grown in the border soil, or in pots of good compost. A popular method of growing these plants is to place pots that have had their bottoms removed onto a 6-inch deep bed of ashes or coarse sand and shingle.
The ashes or single will hold a large quantity of water so the plants do not suffer from drying out as they often do in ordinary pots. Add good compost into the bottomless pots and plant in the young tomato seedlings.
Liquid feeding is applied to the compost at 10- day intervals from the time the first truss has set. Plain water is applied only to the ash or shingle base.
Sowing in Frames
Sow the seeds in April in 3-in. (76mm) pots filled seed compost. Put three seeds, ¼ in. apart and ¼ in. (6mm) deep in the centre of each pot, these can be thinned down to one per pot later.
Tomato seeds germinate at temperatures between 59 to 68 deg F. (15 to 20 deg C.) Keep the pots in the frame until the end of May.
Planting Out in the Open
In readiness for planting out, level the ground raking in fish manure with 10 percent potash content or a complete fertilizer at the rate of 4 or 5 oz. (120g – 150g) to the sq. yd.
The main planting is done in late May in the south and early June in the north when the chance of frost has passed. Disturb the roots as little as possible when planting, make a hole with a trowel and plant the soil with the root ball carefully. Plant so that the top of the ball is about ½ in. below the level of the soil. Firm in the plants then push a strong 4-ft. (120cm) bamboo canes into the ground at the side of the plant.
Sowing in the Open
The seeds are sown in May, three seeds ½ in. (12mm) deep in their growing position then cover with a glass bell or a clear plastic, 5-litre mineral bottle using just the top 2/3rds of the bottle, after the bottom part has been removed. Each sowing must be 15 in. (381mm) apart in rows 2-½ ft. (75cm) apart. Later the seedlings can be thinned down to one plant per station if necessary.
As soon as the first truss of flowers have appeared, give a liquid feed that has a 10 percent potash content once a week throughout the season. Watering regularly will prevent the skins from splitting.
Keep only a single stem on each plant by removing the side shoots, which appear at the point where the leaves join the main stem. Make sure that you only remove the side shoots, making sure that you do not damage the incipient flower truss. The shoots can be simply pinched out between finger and thumbnail.
As the plants grow, tie the stems to the bamboo sticks with soft, green cotton twine or raffia. Make sure that the twine or raffia is not too tight so that it does not cut into the stem as it grows. The best method is to wrap the twine or raffia twice around the bamboo then put a loop around the stem and tie it to the stick with care.
Remove the top inch of the growing point of each plant during the first week of August as the plants stop growing and cropping when the days draw shorter. When the top growth is removed, the sap will be then directed to swell the already formed fruits rather than to make any further growth.
Continue to remove the side shoots. Do not remove the leaves until they turn yellow: they manufacture the elaborated sap that feeds the fruits helping it to mature.
Remove the fruits as they ripen. At the end of the season if you have green tomatoes still on the plants, they can be removed and ripened indoors on a windowsill.