Make full use of your greenhouse over the Winter and early Spring to grow Broad Beans, and potatoes in pots, for the earliest crops. You can grow your first crop of Salad vegetables in pots or fish boxes.
The germination of seeds and the growing of seedlings in the greenhouse can be enhanced if you create a mini-greenhouse at one end, using cheap bubble wrap, stapled to the timber supports, or using double sided tape to attach to metal supports. This allows higher temperatures to be maintained, especially at night, when low overnight temperatures can be expected till Spring or even early Summer.
Growing tomatoes, peppers, aubergines, cucumbers, melons, grapes, etc., is more easily carried out in a greenhouse, especially in the more Northerly parts of the country.
Tomato growing is usually carried out using Grow bags in 30 or 60 litres sizes. The larger size helps to maintain a more even supply of moisture, and thus prevent the splitting of tomatoes, caused by uneven watering. When making the holes to plant the tomatoes in the grow bag, restrict them to 10 cm dia. to cut down evaporation from the grow bag. If your young tomato plants have become “leggy” through growing at too high a temperature and not enough light, just plant them deeper in the grow bag, and they will form extra roots from the buried stem. It is usual to grow tomatoes as cordons up a cane, or cord suspended from a rafter, pinching out all side shoots except the flower trusses. The tomato plants are usually “stopped” by pinching out the growing tip, once there are 6 or 7 flower trusses on the plant. They can be also grown directly in the Greenhouse soil, but you would need to change the soil every year or disinfect it with a Jey’s Fluid solution. Many people fill large pots with sieved garden soil, to grow their tomatoes in, but this risks bringing pests and diseases into the greenhouse unless the soil has been sterilised.
During the growing season, the lower leaves will start to yellow, and these should be snapped off at the stem. If you start to get moulds or blight on the tomato leaves, increase the ventilation and remove badly affected leaves. As a last resort, consider spraying with a suitable fungicide. To ensure fertilization of the flowers, gently shake the flowers with your finger to distribute the pollen. For other cultivation details, go to Tomatoes.
Peppers can be grown from 4 to 6 to a large growbag, while try 3 Aubergine plants to a large growbag. The growbag should be placed on the staging, if you have it, at the back of the greenhouse. To ensure fertilisation of Pepper and Aubergine flowers, gently shake the flowers with your finger to distribute the pollen. For cultivation of Peppers, go to Peppers, and for Aubergines go to Aubergines.
Cucumbers and melons can be grown in grow bags or large pots placed on the floor, and the plants allowed to clamber up netting, cords or canes, attached to the rafters. For cultivation details, go to Cucumber or Melon .
Grapes vines should be planted in the soil, with their roots outside the greenhouse, so that they do not need to be watered. The vines themselves should be trained inside, up to and along a wire hung about 30 cm from the rafters. The wire should be positioned so that the hanging bunches of grapes are out of the way of your head. They should be pruned in the Winter, while they are dormant, as they can “bleed” very badly if they are pruned while the sap is rising. You can “pinch” out the new soft growth in the Summer quite safely, but the harder older growth must only be pruned while the vine is dormant. For cultivation details, see Grape .
Feeding of Greenhouse Plants. This is best achieved by using a proprietary liquid tomato fertilizer, diluted in water.