Growing guide
How to grow tomatoes in Ireland
Tomatoes usually crop more reliably under glass or polythene in Ireland, although a warm sheltered garden can support an outdoor attempt. Before reaching for the secateurs, identify the growth type. Cordon tomatoes are trained as supported stems; bush tomatoes retain their branching shoots. Treating every plant as a cordon removes useful growth from bush varieties.
On this page
At a glance
- Start with
- Seed or healthy young plants; supports suited to bush or cordon habit
- Best position
- A bright greenhouse or tunnel, or a warm sheltered outdoor trial
When and where to start
Indoor sowing. For a typical home greenhouse crop, Teagasc recommends mid-March to early-April sowing, with 15–25 °C for germination. Its outdoor method starts plants under cover in April. Earlier sowing is not automatically better if light and space are limited.
Planting out. Plant when roots fill the pot and first flower buds appear, provided conditions are warm enough. Harden off outdoor plants and wait for local frost risk to pass; Teagasc’s outdoor planting is in June. An unheated greenhouse also needs frost precautions.
Planting and spacing
Sow onto moist seed compost, cover lightly and move seedlings into bright conditions after emergence. Pot them individually when large enough to handle, holding a seed leaf rather than the delicate stem.
Teagasc gives 50 × 50 cm for its outdoor method, with stakes for cordons. Under cover, its booklet allows three plants per standard growbag; check the actual bag and variety rather than applying that number to every container.
Tomatoes can be planted with some stem below the compost surface. Prepare secure supports before growth makes access difficult. Bush plants may still need support for their fruit load, but not single-stem pruning.
Routine care
Tie or twist cordon stems onto their supports. Remove small shoots in the angle between a leaf and the stem when about 2–3 cm long. Leave bush plants’ shoots to develop.
Water the root zone consistently and feed established plants with suitable tomato fertiliser according to its directions. Ventilate in warm weather and avoid unnecessary foliage wetting.
Towards the end of the season, stop cordon growth so existing fruit can finish instead of producing flowers unlikely to ripen. The outdoor guide describes stopping in August; conditions influence the practical timing.
What to watch for
Irregular water supply can contribute to cracking and blossom-end rot. A dark patch at a fruit’s base is a reason to check moisture management, not automatically to add calcium.
Blight is a concern outdoors; humid protected conditions can also favour Botrytis. Check leaves and stems regularly and maintain airflow around plants.
Harvest and storage
Pick at the variety’s ripe colour rather than assuming every tomato turns red. Ripening on the plant allows flavour to develop.
At season’s end, Teagasc suggests bringing remaining green fruit into warmth to ripen, or using it in chutney. Separate damaged fruit and inspect the remainder as it ripens.
Common questions
Should I remove every sideshoot?
No: remove them from cordons, not from bush tomatoes. Check the label before training a plant.
Can tomatoes grow outside in Ireland?
Yes in favourable sheltered sites, but protected cultivation is generally the more dependable option.
Is earlier sowing always better?
No. Poor light can produce weak plants that outgrow their available space before conditions are safe for planting.