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Growing Greenhouse Vegetables

By: Elizabeth Hinds - Updated: 26 Sep 2012 | comments*Discuss
Greenhouse Vegetables Herbs Vegetable

There’s something very special about taking the first bite from a warm tomato you’ve picked from your greenhouse. Supermarket toms just can’t compare. So if you’re new to greenhouse gardening, sit back and prepare for your first time!

We’re going to look at growing vegetables in cool greenhouses, that is, greenhouses that are frost-free but not heated. A cool greenhouse is ideal for sowing hardy seedlings that will later be planted out in your garden, as well as, during the summer, for growing a number of vegetables and herbs.

Tomatoes, peppers, aubergines, cucumbers, melons and herbs can all be successfully grown in a greenhouse. When choosing the seeds, look for those that specify their suitability for greenhouse growing. To ensure successful greenhouse vegetable gardening you want varieties that are bred to have the right qualities.

In the Greenhouse

To grow vegetables successfully in a greenhouse you need a routine..

  • Get into the habit of visiting your greenhouse at set times of the day (if you can).
  • Check the temperature mid-morning.
  • Water the plants in the evening.
  • Shut up the greenhouse last thing at night or when it begins to turn chilly.

Getting Hot

If the temperature in your greenhouse gets too high and stays too high, your plants will suffer. Growth and vigour will be affected.

  • Through the summer, check the temperature in the greenhouse during the morning. If it’s getting too high, open the door and any vents you have. When you’re first getting used to your greenhouse you’ll want to check the temperature on a regular basis during the day using a thermometer kept inside in the shade. Once you’re used to your greenhouse, you’ll be able to adjust its temperature more effectively and less frequently in order to keep it as constant as possible.
  • Don’t water during the heat of the day although if everything is looking very hot and bothered you can damp down your plants.
  • Cover the glass with liquid shading to provide shade and prevent burn on the leaves.
  • Plants don’t like stale air so make sure there is always adequate ventilation.
  • It’s better to let the greenhouse get a little cool than to risk killing all your plants with excess heat.

General Seed Planting Advice

  • Begin with a small pot and seed compost.
  • Soak the compost and leave to drain.
  • Place seeds carefully and well-spaced on top.
  • Sprinkle over more compost.
  • Cover the pot with clingfilm to keep the compost damp and to aid germination.

Growing Tomatoes

Tomatoes are probably the most popular greenhouse vegetables, and the good news is that they’re easy to grow. There’s a huge variety of seeds available providing you with a choice of plum, large or cherry tomatoes. As we said at the start, choose a variety that is bred for greenhouse-growing, that is, one that is a climber rather than a bushy plant.

Sow the seeds into 3” pots in mid-March. By May you should be able to transplant them into 12” pots or gro-bags. As the seedlings begin to shoot up provide a bamboo cane for them to climb around and cling to.

In between the main stem and the sideshoots, tiny little shoots will appear. Pick these out to allow all the growth and goodness to go into the main flowering and fruiting shoots.

Feed regularly. Special tomato food is available at garden stores.

Be a busy bee

Help pollination along by tapping on the bamboo canes when the petals of the flowers are open and curved outwards.

Growing Peppers

Sow pepper seeds indoors in April in 3” pots. When seedlings are large enough to handle transfer individual plants to 8” pots. Water regularly.

Chillies should be allowed to turn red before being harvested but then they can be frozen and stored in a small container in the freezer. Just a couple of plants should keep the average cook supplied for most of the year.

Growing cucumbers

When buying seeds, look out for the FI hybrid varieties, which produce female cucumber plants. If a flower is pollinated by a male plant, the fruit will be bitter-tasting so you don’t want any of those males around!

Sow cucumber seeds in 3” pots in mid-March and transplant into 12” pots when seedlings are big enough. Provide a cane for the plant to grow up. After about 6 leaves have appeared, remove the growing shoot. Water well and feed regularly.

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[Add a Comment]
Hi I work at aSpecial School and have just been given an allotment to use with my students.I am going to teach the Horticulture and am going to enter them for an accreditation.One of the modules is asking to follow a given maintenance plan for growing and caring for vegetables from seed I am quite flummaxed as I don't know much about a maintenance plan and would really appreciate your expert help? Kind regards Pam
PAM - 13-Jul-12 @ 6:05 PM
Im new to greenhouse growing,and have from seed four types of tomato and two cucumbers.all of the tomatoes look unwell with dry whitish patches on the leaves.when the sun shines it gets very hot in the greenhouse,i was wondering should i shade the greenhouse,and is there a product that can be applied.do i take it off in the winter.
mac - 17-May-12 @ 6:24 PM
What is the best wood for making (4) 3ft x 7ft Growing Boxes for the 8 x 16 Rion Greenhouse.... Redwood, Cedar or what? How deep should they be? Thank You! Terry Krueger krueger1010@bellsouth.net
Dinglebutt - 4-May-12 @ 9:24 PM
I have cucumber in pots the leaves are getting quite big but no sign of any flowers on them,is it to late to transplant into the ground?
anna - 29-Apr-12 @ 6:20 PM
Hi I have a question to ask. I am growing cucumbers in my greenhouse, a flower is growing at ground level. How can I save the fruit from contamination when it comes? Regards Trigger
trigger - 7-Jun-11 @ 11:22 AM
I really enjoyed reading your helpful advice and tips, having inherited a rather neglious but spacious greenhouse. I feel quite overwhelmed by the choice of vegetables I could grow but none of the other websites mentioned the time of the year to plant except yours. Thanks very much.
kalamari - 5-Jun-11 @ 3:35 PM
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