Greek vs Genovese Basil: Which to Grow in the UK?

Greek basil and Genovese basil sit side by side in most seed racks, and plenty of gardeners treat them as interchangeable. They are not. Grow both and the differences show within a fortnight: one stays compact and bushy in a 15cm pot, the other stretches upwards and demands space, food and warmth. Choosing between them comes down to what you actually want from the plant — a long, steady trickle of small, punchy leaves, or generous soft leaves for pesto in high summer.

The short answer

If your growing space is a kitchen windowsill, a small balcony or a yard that only catches a few hours of sun, Greek basil will earn its keep. If you have a greenhouse, a warm conservatory or a sun-trap patio and you want to make pesto by the jarful, grow Genovese. Most UK gardeners with room for two pots should grow both, because they do genuinely different jobs in the kitchen.

Greek basil is the forgiving one. Genovese is the productive one. Neither is better — they suit different gardens.

• Leaf size: Greek, roughly 1–2cm; Genovese, 5–8cm.
• Flavour: Greek is peppery and concentrated; Genovese is sweet and mellow.
• Habit: Greek forms a tight, rounded bush; Genovese grows upright and open.
• Cropping: Greek is quick from seed and forgiving; Genovese is slower but far more generous once established.
• Bolting: Greek resists flowering for longer; Genovese runs to seed quickly in heat or drought.
• Best spot: Greek, sunny windowsill or sheltered patio; Genovese, greenhouse or a warm south-facing wall.

Leaf size, and why it changes how you cook

Greek basil leaves are tiny — about the size of a fingernail. You harvest a sprig rather than a leaf, and one sprig gives you a whole cluster at once. That makes it excellent for tearing over tomatoes, scattering across flatbreads or dropping whole into a salad where you want the flavour spread evenly without chewing through a mouthful of leaf.

Genovese produces broad, soft, slightly cupped leaves with real substance. A single leaf is a mouthful. That size is exactly why it became the classic pesto basil: one big handful fills a small processor, whereas you would need to strip dozens of Greek basil stems to get the same weight of leaf.

Picking tips for both

• Pinch with your thumbnails or snip with scissors — tearing bruises the stems.
• Never take more than a third of the plant in one go.
• Cut above a pair of leaves so the plant branches from that point rather than growing a bare stem.
• Pick in the morning, before the heat of the day, for the strongest aroma.

Flavour: sweet and mellow versus peppery and loud

Genovese tastes sweet and faintly aniseedy, with a soft, almost lettuce-like quality and very little bitterness. It is the flavour most people picture when they think of basil. Heat dulls it quickly, so add it at the end of cooking, or keep it raw altogether.

Greek basil is more concentrated: peppery, a little clove-like, with a sharper aniseed note in the background. It stands up well to oil, vinegar and salty cheese, which is why it works so well in dressings, marinades and anything with feta or olives. A few leaves go a long way — start with fewer than you would expect, taste, then add more. In a delicate dish it can easily take over.

Growth habit and what happens in a pot

Greek basil naturally forms a rounded mound, usually somewhere between 20cm and 30cm tall, with tight spacing between the leaves and thin, flexible stems. Left alone it covers itself in tiny white flowers, though it takes longer to reach that stage than Genovese. It copes with being slightly pot-bound and won't sulk if you miss a feed.

Genovese is a bigger, more upright plant, often reaching 45–60cm in a decent season, with thick stems and large leaves. It is hungrier and thirstier than its Greek cousin. Let it dry out and the leaves turn leathery while the plant throws up a flower spike almost overnight. Pinch out the growing tips regularly and it will keep producing side shoots for weeks.

Both are tender annuals in the UK. A frost finishes them, and nights below about 10°C will stall growth rather than kill it.

Which one suits the UK climate better?

Honest answer: outside a greenhouse, in most British gardens, it's Greek basil. It tolerates cooler nights, breezier sites and more erratic watering, and it will still crop on a windowsill that only gets four or five hours of sun a day. It also recovers faster if you neglect it.

Genovese wants the warmest spot you can give it. A greenhouse, polytunnel or conservatory is ideal. Second best is a large pot against a south-facing wall that holds heat into the evening. In a cool, grey summer it grows slowly and may never reach its potential — still worth growing, but don't count on a glut.

Starting both from seed

Sow indoors from March. Greek basil can go a fortnight earlier than Genovese. Press the seed into moist compost but don't bury it deeply, as basil needs light to germinate; seedlings usually appear within a week to ten days at around 18–20°C. Prick them out into 9cm pots once they have a pair of true leaves, then harden them off gradually and plant out after the last frost risk — usually late May or early June across most of the UK.

A practical plan for growing both

1. Sow Greek basil in early March in a small pot on the windowsill. It will crop earlier than anything else you grow.
2. Sow Genovese in two batches three weeks apart, so one batch is producing while the second is still young.
3. Keep them in separate pots. Genovese needs more water and more feed, and sharing a container means one of them loses out.
4. Pinch out the top pair of leaves every week or so from early on, starting when plants are roughly 15cm tall.
5. Feed Genovese every fortnight with a balanced liquid feed once it's growing strongly. Greek basil needs about half that.
6. Water in the morning at the base, not over the leaves, and never let either plant sit in a saucer of standing water.
7. Harvest continuously rather than in one big cut. Regular picking is what keeps both plants leafy and stops them flowering.

The verdict

If you're choosing just one, pick Greek basil for windowsills, balconies and small spaces, and Genovese for greenhouses and serious pesto production. If you have room for two pots, grow both: they occupy different corners of the kitchen and neither takes up much space. Sow a pot of each this spring and you will know within a month which one your garden actually wants to grow.

Photo: Gundula Vogel / Pexels