There’s something so rewarding about growing tomatoes from seed. You get to choose the exact variety you want, nurture them from the very beginning, and enjoy the satisfaction of harvesting tomatoes you raised yourself—right from the soil (or seed tray) up.
I still remember the first time I tried to grow tomatoes from seed. I didn’t have much space – just a sunny windowsill and a whole lot of enthusiasm. I wasn’t sure if they’d germinate, but they did, and I’ve never looked back. Now, it’s one of the garden tasks I look forward to each season. So if you’ve ever wondered where to start, here’s your friendly nudge – start somewhere, and why not start with tomatoes?
Growing Tomatoes from Seed Indoors
If you don’t have outdoor space, don’t worry! You can grow tomatoes indoors year-round with the right setup. I sometimes use my indoor Click & Grow Smart Garden system, and it’s been a game changer for small-space gardening. Check out my full Click & Grow review here.
With a smart garden, you can skip the guesswork- no worrying about light levels, watering, or feeding. Just pop in the seed pod and go. I’ve grown cherry tomatoes in my kitchen all through winter!
When to Start Your Seeds
Tomatoes need warmth and light to thrive. Start your seeds indoors about 6–8 weeks before your last expected frost date. For most regions, this means sowing in late winter or early spring. If you’re short on light, consider using grow lights for growing your tomatoes.
Why Start from Seed?
Buying seedlings is fine, but starting from seed opens the door to so many more varieties- heirlooms, cherries, beefsteaks, paste tomatoes, and colourful options you’ll never see in a punnet. It’s also more economical, especially if you’re planning a bigger garden.
If you’re growing indoors, check out my guide to growing tomatoes indoors with lights—it walks you through how I set up my system in the lounge one rainy winter and still ended up with ripe tomatoes by early spring.
Step-by-Step: How to Grow Tomatoes from Seed
1. Choose Your Tomato Seeds
Look for open-pollinated or heirloom tomato varieties if you want to save your own seed later. Cherry tomatoes are a great option for beginners because they’re generally quick and productive. Check the back of the packet for your region’s ideal sowing time.
2. Use a Quality Potting Mix
This part is so important. Your seeds need a good start – I recommend a potting mix with a peat base (aka spagnum peat moss) that holds moisture but drains well.
I did a little experiment last season with two batches of seedlings: when I transplanted them, I planted a few in a cheap garden mix from my local garden center, and the other in high quality peat-based mix from a trusted landscape supplier. The difference was unbelievable! As you can see in the image below, same seeds, same conditions – but the ones in peat based mix absolutely thrived! It just proves my point of how crucial it is to invest in good potting mix or compost if you want good results.
3. Sow Your Tomato Seeds
Plant seeds about 5 mm deep into moist potting mix. You can use seedling trays, or make recycled seedling pots out of things from around your home like yoghurt pots – anything with drainage. Cover lightly and keep somewhere warm (around 68-77°F/ 20-25°C). A seedling heat mat or a sunny windowsill works wonders.
4. Keep Them Moist and Warm
Your seeds should germinate within 5–10 days. Keep the soil evenly moist (not soggy) and warm during this time. Once they sprout, move them to a bright spot or under grow lights.
5. Transplant to Bigger Pots
Once your seedlings have two sets of leaves (this second set are called their “true leaves”), transplant them into larger pots. Bury them up to the first leaves to encourage strong root growth. If your seedlings are leggy, this trick helps them catch up nicely.
When and How to Sow Your Seeds
The best time to start growing tomatoes from seed depends on your climate. As a general rule of thumb, sow your tomato seeds in late winter to early spring, about 6–8 weeks before the last expected frost. Use a quality seed-raising mix and clean containers with good drainage.
- Fill trays or small pots with seed mix.
- Plant seeds about 0.5cm deep and water gently.
- Keep warm – around 68-77°F (20-25°C) is ideal. A heat mat or sunny windowsill works wonders.
- Once they sprout, move them into bright light to avoid leggy stems.
- Water gently and keep the soil moist but not soggy.
- Once they develop true leaves, transplant them into larger pots and keep them growing strong.
Hardening Off Before Transplanting
Before planting outdoors, “harden” seedlings off gradually. About a week before transplanting, introduce them to the outdoors for a few hours a day, increasing time and sun exposure slowly. This helps them adjust to a different environment and avoids transplant shock.
Choosing the Right Spot
Tomatoes love warmth and sun – choose the sunniest spot you’ve got. Prepare the soil with compost, well-rotted manure, or your favourite organic mix. Tomatoes are heavy feeders, so they need the nutrient boost.
Stake or cage tomato plants early on to avoid damaging roots later. Water deeply and regularly, but avoid wetting the leaves to help prevent disease.
Common Pests and Diseases
Tomatoes are tough but not invincible. Watch out for:
- Early and late blight
- Blossom end rot
- Tomato mosaic virus
- Aphids and whiteflies
To minimise issues:
- Rotate crops each year
- Mulch the base of plants
- Water at the base (not overhead)
- Remove any diseased leaves quickly
I also make a natural anti-fungal spray using essential oils- check out this recipe here. It’s been a lifesaver when I spot early signs of fungal issues.
Saving Your Own Tomato Seeds
Once you’ve found a tomato variety you love, why not save your own seed for next year? Here’s how I do it:
- Choose a healthy, fully ripe tomato from a disease-free plant.
- Scoop out the seeds into a jar with a little water.
- Let it sit for a few days to ferment—this helps break down the gel coating.
- Rinse the seeds thoroughly and dry them on a paper towel or plate.
- Store in a labelled envelope somewhere cool and dry.
Saving your own seed not only saves money but also helps you build resilience in your garden. Just be aware that you can only reliably save seeds from heirloom or open-pollinated (non-hybridised) plants, as these will grow true to type. Hybrid or genetically modified seeds often won’t produce consistent results in future generations, so they’re not ideal for seed saving.
Harvesting Your Tomatoes
Most varieties are ready 60–85 days from transplanting. You’ll know they’re ripe when they’re fully coloured and slightly soft to the touch. Don’t leave them too long on the vine or they can crack—especially if it’s been rainy.
And when you’ve got more tomatoes than you can eat (it’ll happen!), why not try preserving some? Here’s my Introduction to Canning for Beginners to help you get started.
Tomato Growing FAQs
Can you grow tomatoes from fresh tomato seeds?
Yes, you can grow tomatoes from fresh tomato seeds, but it’s best to let them ferment first. The gel around the seeds contains growth inhibitors, so allow the seeds to sit in water for a few days until a light mould forms. Then rinse and dry before planting.
How long does it take to grow tomatoes from seed?
From seed to ripe fruit usually takes around 100–120 days. That includes 6–8 weeks indoors before transplanting, and about 60–85 days from transplant to harvest, depending on the variety.
Do tomato seeds need light to germinate?
No, tomato seeds don’t need light to germinate, but they do need warmth. Once they sprout, move them into bright light to grow strong and avoid legginess.
Why are my tomato seedlings leggy?
Leggy seedlings are usually caused by not enough light. If your tomato seedlings are stretching, try moving them closer to a bright window or under grow lights.
Do I need to soak tomato seeds before planting?
You don’t need to soak tomato seeds before planting, but some gardeners like to for a head start. A short soak in water (for an hour or so) can speed up germination, but it’s not essential.
Can you grow tomatoes all year round indoors?
Yes, with the right setup—grow lights, warmth, and good airflow—you can grow tomatoes indoors year-round. I’ve done it in winter and still had a great harvest. Check out this article for my indoor tomato setup.
Ready to Grow?
Growing tomatoes from seed is one of those gardening tasks that’s equal parts satisfying and addictive. It might feel a little daunting at first, but once you’ve seen your first batch thrive, you’ll be hooked—trust me. Whether you’re starting with a sunny windowsill, an indoor gardening system, or a full greenhouse setup, the key is just to start.
Choose a variety you love, give your seedlings a healthy start with good quality mix, and enjoy the journey from seed to harvest. You don’t need a big backyard or years of experience- just a little patience and a willingness to learn as you grow.
So go on- give growing tomatoes from seed a go. Your future self (and your summer salads) will thank you.
About the Author
Elle Reed is a passionate gardener and advocate for teaching beginner gardeners how to grow their own food. Elle’s mission is to inspire and empower people to get back to basics, grow their own produce, and embrace a sustainable lifestyle. “Whether it’s a few herb pots in an apartment, a potager or a full garden plot, we can all ‘start somewhere’ to grow our own food, and in doing so, provide healthier food for ourselves and those we love”.
