Growing tomatoes: outdoors vs in a greenhouse
Tomatoes are the crop everyone wants to get right, and the first big question is where to grow them. A greenhouse gives you a longer, surer season and a real edge against blight; outdoors, in a warm and sheltered spot, you get tomatoes that many swear taste even sweeter for the open air. The truth is you can grow a cracking crop either way — you just grow them a little differently.
Here's how the two compare, and how to get the best from whichever you choose. For sowing dates and our opinionated variety picks, see the tomato crop page; and if you're raising your own from seed, our seed-starting kit guide covers the trays, compost and warmth that get them off to a flying start.
Outdoor vs greenhouse at a glance
| Greenhouse | Outdoors | |
|---|---|---|
| Season | Longer — earlier to plant out, ripens later into autumn | Shorter — wait until after the last frost, finishes earlier |
| Blight risk | Low — dry leaves rarely catch it | Higher — wet summers bring it on; choose resistant varieties |
| Varieties | Anything, including the tender, fancy and beefsteak types | Best with quicker, hardier and blight-resistant kinds |
| Watering | Daily in heat — pots and growbags dry fast | Rain helps, but still water steadily in dry spells |
| Pollination | Give plants a tap or open the door for airflow and insects | Wind and insects do it for free |
| Flavour | Excellent — and the most reliable ripening | Often superb — many say the sweetest tomatoes of all |
Cordon or bush? Know which you've got
The other thing that changes how you grow a tomato is its habit, and it's worth checking the packet before you sow — the two are managed completely differently.
- Cordon (indeterminate)— grows as one tall stem. Tie it to a cane or string, pinch out the side shoots that appear where each leaf meets the stem, and “stop” it (nip the growing tip) once it has set four or five trusses outdoors, more under glass. The classic greenhouse and supported-row tomato. Cordon tomato seeds →
- Bush (determinate)— branches low and sprawls to a set size, then crops more or less all at once. No side-shooting, no stopping — just let it go. Perfect for pots, hanging baskets and easy outdoor growing. Bush tomato seeds →
Feeding, watering & the steady hand
Whichever way you grow them, two things make or break the crop: even watering and the right feed. Tomatoes loathe a drought-then-deluge rhythm — it splits the fruit and brings on blossom end rot (that sunken black patch on the base). Water consistently, aiming at the soil rather than the leaves, daily for pots in hot weather.
Once the first truss of flowers has set, switch to a high-potash tomato feed once a week — it steers the plant's energy into fruit rather than leaf. Keep removing the lower leaves as the trusses ripen, for airflow and to put the sun on the fruit, and pop a few pollinator flowers nearby — see companion plants for tomatoes.
Common questions
Are greenhouse tomatoes better than outdoor ones?
A greenhouse gives a longer, more reliable season, more variety choice and far better blight protection. But outdoor tomatoes grow well in the UK with the right varieties and a sunny, sheltered spot — and many think they taste even better. Use a greenhouse if you have one; grow outside with confidence if you don't.
What is the difference between cordon and bush tomatoes?
Cordon (indeterminate) types grow as one tall stem you tie up, side-shoot and stop — ideal for greenhouses and supported rows. Bush (determinate) types branch low, sprawl, need no pinching out and crop all at once — perfect for pots and low-fuss growing.
How often should I feed and water tomatoes?
Water consistently — little and often beats drought-then-flood, which splits fruit and causes blossom end rot. Once the first truss sets, feed weekly with a high-potash tomato feed. Pots and growbags need daily watering in hot weather.
How do I stop tomato blight?
Greenhouse plants mostly escape it (dry leaves). Outdoors, grow blight-resistant varieties, give plenty of airflow, water the soil not the leaves, keep tomatoes away from potatoes, and watch our live blight risk so you can act early.