Updated January 2026

A flavour-first guide from Fat Tomato

Anthony holding a Tomato Pineapple Ananas

There’s nothing quite like the taste of a homegrown tomato. At Fat Tomato, we grow over 100 heritage and heirloom tomato varieties, chosen for flavour, curiosity, and resilience rather than uniformity or shelf life.

Most of our tomatoes are grown in our polytunnel, with a small number grown outdoors in raised beds when conditions allow. We grow exclusively from organic, chemical-free, open-pollinated seeds - they’re easier to grow, better for the soil, and, most importantly, produce tomatoes with real depth of flavour.

Each year, we hand-select a few exceptional plants to save seed from, which we then offer through our online shop so you can grow the same varieties at home.

1. Choose the Right Tomato Variety

Start by thinking about:
- the space you have - polytunnel, greenhouse, raised bed, or pots
- your local microclimate
- how you like to eat tomatoes
- Tomatoes come in many forms - cherry, plum, salad, globe, beefsteak, and oxheart - each suited to different uses and growing conditions.
Growing outdoors in Ireland: Choose varieties that tolerate cooler Irish temperatures, occasional damp, and will ripen without the extra warmth of a polytunnel or greenhouse.
Growing in pots: If space is limited, go for compact, fast-ripening cherry tomatoes. We particularly love Latah, Maskotka, Clementine, Mini Marzano, and Yellow Submarine for their speed, reliability, and flavour.
Seed choice matters: Always choose organic, chemical-free, heritage open-pollinated seeds from trusted suppliers. At Fat Tomato, we do not grow GM or F1 varieties - you can’t save seed from F1s, and they’re mostly bred for uniformity rather than flavour.
Irish seed savers and suppliers worth supporting include Brown Envelope Seeds, Irish Seed Savers, and Fat Tomato!
Browse our heritage, open-pollinated tomato seeds on our Online Shop here.

Ingredients for Cooks and Gardeners

Tomato Brad's Atomic Grape Seeds

€4.00

2. Prepare for Sowing Tomatoes indoors

Timing:
- Start seeds 6 to 8 weeks before your last expected frost.
- In most of Ireland, this means sowing from February to March. Some people start sowing in January, but you need to make sure you can maintain heat and light, as seedlings might not survive.
- At Fat Tomato, we sow in small batches from February to April on a heated bench in our polytunnel, giving us a steady supply of tomatoes right through to November - and often December in good years.
- You can sow tomatoes up until May if you choose quicker or later-season varieties.
Supplies needed:
- Organic, chemical-free tomato seeds
- Seed or modular trays or small pots
- Seed labels
- Organic peat-free seed compost
- Organic peat-free potting compost
- Vermiculite
- Spray bottle or fine watering can
- Heat mat or heated bench (optional but ideal)
- Grow lights (if natural light is limited)
- Clear plastic cover or cling film (optional, for humidity)

3. Prepare the Seed compost

Soil mix: Mix a handful of vermiculite into your organic peat-free seed compost. You should be able to see small flecks of it in the mix. Vermiculite is used to keep the soil moist, improve soil aeration, and support germination.
Seed trays: Fill your seed trays.
Moisten the mix: Lightly dampen the compost before sowing. It should be moist, not soggy.

4. sow the Seeds

Sowing depth: Sow tomato seeds approximately 0.5cm deep.
Spacing: In trays, space seeds 2cm apart. In small pots: sow 2 to 3 seeds per pot.
Cover: Lightly cover the seeds with a thin layer of the soil mix above. You can also just do a light sprinkling of vermiculite.
Labels: Always label each variety and include the sowing date on the back.

5. Create Ideal Growing Conditions

Temperature: Seeds germinate best at 20°C to 27°C. If available, use a heat mat or heated bench. A sunny windowsill will also work - check regularly to prevent the compost from drying out.
Humidity: To retain moisture, cover the trays with a plastic dome or cling film. Remove the cover once the seeds have germinated.
Light: Seedlings need 12-16 hours of light daily after germination. If indoors without much natural light, use grow lights. Keep the lights a few centimetres above the seedlings to prevent stretching. The term you will hear gardeners saying is legginess, which means the plant is looking for light, growing weak stems and sparse foliage.

Growing organic Tomato seedlings in tray — Tomato seedlings in tray with some potted up on the right

6. Watering and Care

Watering: Keep compost lightly moist. Mist early on, then water at the base once seedlings are established. Avoid wetting leaves as tomato plants dislike it.

7. Transplanting into Larger Pots

When to transplant: Once seedlings have 2 to 3 sets of true leaves and strong root development, they’re ready to move to larger pots.
Potting up: Transplant each seedling into an individual small-to-medium-sized pot. Handle with care to avoid damaging the roots. If your seedlings are leggy, you can bury part of the stem in the compost - tomatoes grow roots from buried stems, strengthening the plant.
We don’t usually return plants to the heated bench at this stage unless the weather turns unusually cold.

8. Harden Off the Seedlings

Acclimatisation: If sowing tomatoes outdoors, begin hardening off around 7 to 10 days before planting out. Gradually expose seedlings to outdoor conditions by placing them in a sheltered, shaded area for a few hours each day. Increase their time and light exposure gradually to help them adjust without stress.

9. Prepare the Garden BedS or Containers

Site selection: Choose a sunny location - tomatoes need 6 to 8 hours of direct sunlight daily. Good drainage is essential.
Soil preparation: For in-ground planting, enrich the soil with organic compost or well-rotted manure. For containers, ensure they’re deep (at least 50cm) and offer proper drainage. Tomatoes have deep root systems and thrive in larger pots.
Spacing:
- Determinate (bushy) varieties: space 50cm apart
- Indeterminate (vining) varieties: space 60cm apart
In Ireland, planting out usually happens from late May onwards, once frost risk has passed.

10. PlantING

Plant deep: Bury the seedlings deeper than they were in their pots, up to the first set of leaves. This encourages additional root development along the buried stem.
Label: Label each plant clearly with its variety. We use brown tape, attaching it to the string/support structure.
Water well: After planting, water thoroughly to settle the soil around the roots.

11. Support

Staking or stringing: Use stakes, canes, or string supports to keep plants upright and off the ground - this improves airflow, reduces disease, and makes harvesting easier.
At Fat Tomato, we string tomatoes from roof wires in the polytunnel, burying the twine under the plant at planting time.
Tie gently: As plants grow, loosely tie stems to supports using soft garden twine or fabric strips to avoid damage.

12. Ongoing Care, FEEDING and pruning

Watering: Water consistently - deep and less frequent watering encourages strong roots. Avoid wetting the leaves to prevent fungal problems. We water every second day until fruiting begins, then switch to every fourth day to concentrate flavour - watery tomatoes are no good.
Mulching: Apply a layer of organic mulch (straw, grass clippings, sheep wool, or shredded leaves) to help retain moisture and suppress weeds. We love sheep wool as it keeps the soil warm and moist and naturally breaks down, feeding the soil with nutrients.
Feeding: Feed fortnightly if needed, using organic fertilisers. We use a mix of homemade Comfrey tea and organic seaweed feeds.
Pruning: For indeterminate (vining) varieties, remove side shoots (“suckers”) from where branches meet the main stem to encourage airflow and direct energy into fruit production. Once plants reach the desired height, pinch off the growing tip to stop vertical growth and boost fruiting. Add pruned leaves and stems to your compost heap - despite common myths, healthy tomato leaves can be composted without issue.

Fat Tomato heritage tomatoes — Tomatoes growing in our polytunnel with Nasturtiums and French Marigolds

13. Pest and Disease

Inspect regularly: Check your plants frequently for common pests such as aphids, whiteflies, and tomato hornworms. At Fat Tomato, we use companion planting to naturally deter pests - sowing basil, nasturtiums, and marigolds between the tomato plants.
Disease prevention: Maintain good airflow by properly pruning and spacing your plants. Avoid overhead watering to reduce the risk of fungal diseases, such as blight.

14. Harvesting

When to harvest: Tomatoes are ready to pick when they are fully coloured and slightly soft to the touch.
Remember, not all tomatoes ripen red - some turn yellow, orange, purple, or even black.
Harvesting: Use garden scissors, pruners, or your fingertips to gently cut the fruit from the vine, leaving a small part of the stem attached. Not all tomatoes on a truss will ripen at the same time.

15. STORAGE AND PRESERVING

Storage: Store your tomatoes at room temperature, out of direct sunlight. Never refrigerate them - cold temperatures can ruin both flavour and texture.
Preserve: If you end up with a glut, freeze overripe tomatoes for winter use in soups, stews, or sauces. You can freeze whole tomatoes in tubs or compostable bags.
At Fat Tomato, we turn our harvest into everything from chutneys and jams to rich tomato sauces.