Time to Start Growing your Vegetables

A greenhouse is suitable for growing vegetables in a number of ways:

• Starting off hardy vegetable plants earlier than outdoors
• Growing tender crops such as aubergines, cucumbers, peppers and chillies and tomatoes through the summer months
• Making use of the autumn sun to raise late salad crops, French beans and even calabrese

What to plant this Spring

A productive greenhouse can be in use for most of the year. Heated greenhouses allow for maximum, year-round use but are rarely cost effective.

Mid-spring

• Sow fast-growing tender plants such as courgettes, squashes and pumpkins, cucumbers, French beans, melons and sweetcorn so they are ready for planting in their final positions under glass in late spring or outside in early summer. A heated propagator will help ensure germination
• Buy ready-grown pepper and tomato plants for introducing to unheated greenhouses
• Sow basil for growing on indoors or moving outside in summer

Late spring to early summer

• Plant summer greenhouse plants into their final positions indoors
• Harden off and plant out young plants of outdoor crops once the frost has passed

Using your Greenhouse

1. Planning

• Measure out your greenhouse beds and floor space for growbags. Check you have room to space out all the summer greenhouse crops you plan to grow
• Benches should provide plenty of space for seedlings, many of which will be moved outside when the space is needed for summer greenhouse crops
• A catch crop of salad leaves can be sown in greenhouse borders before the space is needed for summer greenhouse crops

2. Sowing seeds indoors

• Use clean pots and trays and fresh, peat-free seed or multipurpose compost
• Follow instructions on the seed packet
• Seeds will germinate on a sunny windowsill indoors or a heated propagator unit in the greenhouse (be aware that in cold weather, in unheated greenhouses, the propagator may struggle to maintain warm temperatures)

3. Growing on

• Once germinated, seedlings will need somewhere light and frost-free to grow on; an unheated greenhouse may not be sufficiently warm until April
• Consider fleecing and heating a partitioned section of your greenhouse to make a suitable environment for growing on tender plants
• Watch weather forecasts and be prepared to protect young plants with fleece on frosty nights or provide supplementary heating when needed

4. Planting

• Plant protected crops into their final positions as soon as they are sturdy and well-rooted
• Plant into greenhouse borders,containers or growing bags
• Growbags can be used for autumn salads – remove a long panel from the top to create a shallow bed
• Ensure climbing plants such as cucumbers and melons have sufficient support and tie cordon tomatoes into strings or canes

5. Summer maintenance

• Check watering daily or install irrigation; uneven watering can result in problems such as blossom end rot in tomatoes
• Ventilate greenhouses on warm days by opening doors and vents; automatic ventilation is ideal
• For warmth-loving okra and cucumbers, vents can be kept closed but humidity must be raised by damping down. Alternatively, partition off a section of the greenhouse with fleece or clear plastic
• Some shading will be necessary; it is best to add this gradually, as it will initially reduce growth
• Hang yellow sticky traps to provide early warning of pests.Biological controls can then be ordered promptly
• Tie new growth into supports regularly; pinch out side-shoots of cordon tomatoes