Shirley F1
The variety to grow if your greenhouse is unheated and your summer is unreliable.
Shirley was bred for exactly the situation most Irish gardeners are in: an unheated greenhouse, a cool spring, and a summer that may or may not turn up. It sets fruit at lower temperatures than almost any other medium-sized tomato, it crops early and heavily, and it carries useful disease resistance. It is not the most exciting tomato on flavour, but it is the one that delivers when conditions are against you.
Quick facts
- Botanical name
- Solanum lycopersicum
- Type
- F1 hybrid
- Category
- Medium salad, cordon
- Difficulty
- Moderate
- Hardiness
- Tender, no frost tolerance
- In Ireland
- Much better under cover
- Germination
- 7 to 14 days at 18 to 25C
- Sowing depth
- 5mm
- Spacing
- 45cm apart, 75cm between rows
- Height
- 1.8m
- Position
- Full sun
- Containers
- Grows well in pots
- Sowing to harvest
- 16 to 20 weeks
- Harvest
- July to October
- Award
- RHS Award of Garden Merit
Sowing and harvest calendar for Shirley F1
Months shaded below are the reliable windows for Irish conditions.
Where to buy Shirley F1 tomato seeds in Ireland
Irish suppliers that stock this, so postage stays domestic and seed arrives in time to sow. These are plain links, not paid placements.
Garden centres and mixed retailers
- Mr Middleton Irish Mail order arm of a long established Mary Street shop, carries the familiar named varieties the organic specialists skip. Visit Mr Middleton , Co. Dublin
- Johnstown Garden Centre Irish Stock runs out by midsummer, best ordered in spring Third generation family business near Naas with the widest branded range, though popular varieties sell out by midsummer. Visit Johnstown Garden Centre , Co. Kildare
Why it suits Ireland
The single most common reason an Irish greenhouse tomato disappoints is cold nights during flowering. Shirley was selected to set fruit through exactly that, which is why it has been a standard recommendation for unheated glasshouses in Britain and Ireland for decades and holds an RHS Award of Garden Merit.
Its built-in resistance to leaf mould is the other quiet advantage. Leaf mould thrives in the humid, poorly ventilated conditions of a small greenhouse in a damp climate, which describes most Irish back gardens in August.
Growing notes
Grow as a cordon with side shoots removed weekly. It is less vigorous than Sungold, reaching around 1.8m, and the trusses are held close to the stem so it is easy to manage in a small space.
Because it crops early and all at once more than some cordons, allow six trusses under cover and stop it in mid-July. Feed with high potash from the first set fruit.
Ventilate the greenhouse whenever the weather allows, even on dull days. Shirley’s leaf mould resistance helps but it is not a substitute for moving air.
Common questions
What makes Shirley good for an unheated greenhouse?
It sets fruit reliably at lower night temperatures than most varieties. Many tomatoes drop their flowers when nights fall below about 12C, which happens regularly in an Irish greenhouse in May and June, whereas Shirley holds on and sets a crop anyway. That is the difference between an early harvest and waiting until August.
How does Shirley taste compared to Gardener's Delight or Sungold?
Honestly, less good. Shirley is a clean, pleasant, slightly acidic salad tomato rather than a memorable one. It is chosen for yield and reliability. Many Irish growers plant two Shirley for the crop and one Sungold for the flavour, which is a sensible compromise.
Is Shirley resistant to blight?
No. Shirley has resistance to greenhouse problems including tomato mosaic virus, cladosporium leaf mould and fusarium, but not to late blight. Under cover that matters much less, since blight needs wet leaves to take hold, which is another argument for growing it in a greenhouse rather than outdoors.
More tomatoes to consider
Gardener's Delight
Open pollinated / Cherry, cordon
The safest first tomato for an Irish garden, and still one of the best tasting.
Growing notes and stockistsSungold F1
AGMF1 hybrid / Cherry, cordon
The best tasting tomato most people will ever eat, and worth the hybrid price.
Growing notes and stockistsAlicante
Open pollinated / Medium salad, cordon
The most flexible old variety here, happy in a greenhouse or a sheltered outdoor bed.
Growing notes and stockistsMoneymaker
Open pollinated / Medium salad, cordon
Dependable and cheap, but there are better tasting varieties for the same effort.
Growing notes and stockists