The Veg Plot

Greenhouse gardening: five top tips on how to grow tomatoes

Healthy tomato plants in greenhouse

If, like me, you’re the lucky owner of a greenhouse (you can read our how-to-put-up-a-greenhouse guide here) then you’ll be grateful that it allows loads of plants to grow at a much faster rate than those left outside in the miserable British weather. The fastest developers in our greenhouse are undoubtedly the tomatoes: they are easy enough to grow in most conditions and a doddle under the warmth of clear glazing.

Even though anyone can grow them, there are a few bits of advice worth following to help them fulfil their tomatoey potential. Here are our five top tomato growing tips…

snip shoots from tomatoes

Support, ripen and snip out those shoots…

Our top five tips for growing tomatoes in your greenhouse

1 Water
Tomatoes are thirsty fruit. Give them a good guzzle of water when you first plant them and continue to water regularly. However, it’s worth treating them a bit mean in the early weeks by skipping a few days. This will stop their roots lazily lapping up the moisture within the immediate vicinity, encouraging them to go roaming to find more. The result will be stronger plants.

2 Feed
Despite what every expert and fruit-feed manufacturer says, you don’t need to feed tomatoes in order to get a harvest. But if you want bigger, better yields it sure does help. You can buy food (usually called something with ‘tom’ in the title such as ‘Tomogrow’*) or you can make your own. Nettles chopped up and left to soak in water works (although it’s a bit stinky) as does watered down manure (equally stinky). Comfrey and seaweed mulches are also recommended.

3 Air
Although your tomatoes will love the tropical steamy conditions created by your greenhouse, they will also benefit from a bit of air to circulate through an open window or door. Not only will this allow pollinating insects easier access than by forcing their thoraxes through gaps in the construction, but it will also create a more stable growing environment and discourage nasty damp-related diseases from taking a grip. Furthermore, when temperatures reach scorching levels during the day, they usually plummet at night, and this exaggerated shift on the thermometer ain’t much fun for a plant.

4 Support
If you think tomato plants are so clever, what with their quick growing and showy, tempting bright red fruits, then why do they have such feeble stalks that collapse as soon the first tomato adds its weight to their structure? Eh? Give them a hand and keep them in a vertical position by gently tying to stakes or creating a framework of string for them to lean against.

5 Snip
Turn your back for two minutes and those eager growers will be sprouting shoots between leaf and stem. Unless you’re growing a bushy variety you should regularly snip them out with a pinch of your fingers. You don’t want excess energy going into side shoots – keep the plants climbing high and fruiting big. Another snip at the top of the plant is advisable when you’ve got a good amount of fruits set to focus energy into the harvest, rather than the rest of the plant. You can then also dispense with leaves at the bottom of the plant – these will just get in the way while you’re picking and prevent air from circulating between plants.

*We don’t think ‘Tomogrow’ actually exists. Looking for a name for your new tomato feed business? Have it and thank us later…

For more information about our Palram Harmony greenhouse check out their website here


  • The tip on skipping a few days of watering at the beginning is very clever, as like a lot of plants tomatoes become “lazy” too. This will make the plants start searching for water if an unexpected drought hits or you fail to water them on time sometimes.
    It was interesting to read!

    • Thanks Abby
      I’m particularly good at the occasional watering failure so they gotta learn to expect an occasional man-made drought!

  • Last year in my polytunnel I prepared the ground with farmyard manure, well dug it in, planted 2 rows of 8 tomato plants, watered them well then left them to it. Snipped any outer growths and kept eye on them. Only watered them in extreme heat. I had the most tomatoes ever and even now in march ive still got loads of tomatoes in my freezer. My granddad used to say leave them alone and they will root down for water etc.

    • Granddad knows best!
      Thanks for posting this and I hope you get through the frozen toms before this year’s bountiful harvest kicks in

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