Supermarket tomato trick: grow a whole tray of seedlings from one tomato

When you see the price of tomatoes in the shops each spring, it is easy to wonder whether growing your own is worthwhile again. A British gardening expert has now demonstrated a method that turns just one tomato into a whole tray of young plants – with no costly seed packets and using materials you probably already have at home.

Why this tomato trick is especially appealing right now

Tomatoes are a perennial favourite in kitchens across the UK. Whether they are used in salads, pasta sauces or sandwiches, they regularly find their way into the shopping basket. At the same time, food prices have risen noticeably. Anyone with a balcony, patio or simply a sunny windowsill can grow at least some of their own summer tomatoes with a little patience.

That is exactly where this straightforward supermarket tomato trick comes in. Rather than buying seeds, you use the seeds already inside the fruit. The key point is that there is no need to painstakingly remove them: they remain in the slices. One tomato can therefore produce a dense “carpet” of seedlings, which can later be separated and grown on.

With very little effort, an everyday item from the chilled aisle can become a small tomato plantation for summer.

The tomato-slice trick: step-by-step method

What you will need

• 1 ripe supermarket tomato, ideally a flavoursome variety
• 1 empty plastic fruit or vegetable punnet with drainage holes in the base
• Seed compost or fine multipurpose compost
• A watering can or spray bottle
• A bright spot by a window or in a greenhouse

How to do it

Gardening expert Simon Akeroyd shows just how easy this technique is in a viral video. Instead of starting with loose seeds, he begins with a shop-bought tomato.

1. Prepare the container: Fill the plastic punnet – for example, one that previously held grapes or berries – with seed compost. Firm it gently and moisten it; the compost should be damp but not soaking wet.
2. Slice the tomato: Cut the tomato into four or five fairly even slices. Each slice contains dozens of seeds.
3. Arrange the slices: Lay the tomato slices flat on the compost surface, leaving a little space between them.
4. Cover lightly: Scatter a thin layer of compost over the slices, just enough to cover the flesh.
5. Moisten carefully: Water gently with a spray bottle or a very fine rose, so that the slices are not washed out of place.

Put the punnet somewhere warm and bright – a sunny windowsill is perfectly adequate. After around one to two weeks, a thick covering of tiny green tomato seedlings will usually begin pushing through the compost.

The clever part is that both the packaging and the fruit are put to use: waste becomes a propagation station.

What to do after germination

Once the seedlings develop their first “true” leaves – rather than only the two very narrow seed leaves – the most important stage begins: pricking them out. Leaving every seedling where it is risks producing weak, disease-prone tomato plants that will later yield only a small number of fruits.

Choosing the strongest tomato seedlings

• Pick the most robust seedlings that are growing upright.
• Always hold a seedling by a leaf, never by its stem, as stems snap easily.
• Use a pencil or spoon to lift the compost slightly, then carefully loosen the root ball.
• Plant each seedling in its own small pot of fresh compost and water it thoroughly.

Any remaining seedlings can go onto the compost heap. It may feel ruthless, but it saves space and effort while preventing too many plants from restricting one another’s growth.

Timing and care in Germany, Austria and Switzerland

The expert starts this tomato trick in spring in Great Britain. The approach can also be applied in Germany, Austria and Switzerland. The crucial factor is that there must no longer be a risk of frost when the plants are moved outside.

Region	Recommended indoor starting time
Southern Germany, lower-lying areas of Austria and Switzerland	Late February to mid-March
Upland areas, northern Germany	Early to late March
Cooler locations, the Alps and high valleys	March to early April

The young plants should remain indoors, in a conservatory or in a greenhouse until the final night frosts have passed. Before planting them out, it is worth hardening them off for a week: place the pots outdoors in partial shade during the day, then bring them back inside in the evening. This helps the plants adjust to wind, fluctuating temperatures and sunlight.

Helping the plants produce plenty of fruit

• Position: Choose a sheltered site with at least six hours of sunshine daily.
• Watering: Keep the compost evenly moist but avoid waterlogging. Water less often, but deeply.
• Feeding: Once flowers start to form, feed regularly with tomato or vegetable fertiliser.
• Support: Use a cane or plant support so stems do not bend under the weight of the fruit.
• Removing side shoots: For cordon tomatoes, remove shoots growing in the leaf axils so the plant directs its energy into fruit production.

Plants that receive a good balance of light, warmth, water and nutrients will usually reward you with a considerable harvest.

What to bear in mind with a supermarket tomato

Technically, this trick works in almost every case because a tomato contains plenty of viable seeds. However, several points can have a noticeable effect on the outcome:

• The variety: Supermarket tomatoes are often high-yielding cultivated varieties. The resulting plants may vary and will not always be identical to the original fruit. For amateur gardeners, that is usually not a problem and may even be interesting in terms of flavour.
• Treatment of the fruit: In some countries, wax-based coatings or treatments are used. Seeds in Europe will generally still germinate, although poor germination may be linked to this.
• Disease: Tomatoes from commercial production are healthy in many cases. There remains a small risk of seed-borne disease, although it is usually manageable for home growers.

For extra reassurance, combine this trick with an organic tomato or a particularly flavoursome variety from the premium produce section. That improves the chances of producing tasty offspring.

Why the effort is worthwhile for balconies and gardens

The most obvious benefit is that home-grown tomatoes can save a noticeable amount of money. A pack of high-quality tomatoes can easily cost several pounds. If the experiment succeeds, a handful of plants can provide fruit for salads, sandwiches and sauces for weeks.

There is also the flavour. Tomatoes picked ripe from your own pot or bed have not spent days sitting in a chilled display. Many home gardeners rave about their more intense taste and better texture. Sustainability is another advantage: reusing plastic punnets creates less waste and conserves resources.

For families with children, this method makes a small but engaging experiment. Children can watch a slice gradually become a plant that later produces edible fruit. It also makes getting started with gardening feel less daunting, even without a garden and with only a windowsill available.

Extra tips for even greater tomato success in spring

Anyone already raising tomato plants can easily take the process a stage further. Many gardeners combine the slice method with conventional sowing in small pots, adding particular varieties such as colourful cherry tomatoes or beefsteak tomatoes. This creates a varied mix of experimental supermarket offspring and deliberately selected varieties.

It is also sensible to consider the growing position. South-facing balconies can become extremely hot at the height of summer. In that situation, light shade during the midday heat can stop leaves and fruits from scorching. Anyone with only a north-facing window can provide extra light with a simple grow light. Tomatoes react strongly to insufficient light: they become tall and spindly, then produce fewer flowers later on.

Air circulation is another often overlooked issue. Humid air can quickly build up where plants are packed closely together in containers or a greenhouse. That encourages fungal diseases such as tomato blight. Leaving sufficient gaps, removing side shoots regularly and ventilating occasionally can significantly reduce this risk – including for plants grown from a supermarket tomato.

Those who try the experiment usually find that making the first cut into the tomato is the hardest part. Once the punnet has been filled with compost and slices, nature does much of the work itself – and, in the best case, you may be leaning over your plate beneath your own tomato jungle in summer.