How to Grow Tomatoes from Seed: Your April Guide | Hortiwool
Ask any gardener what they're most looking forward to growing this summer, and the chances are tomatoes will be at the top of the list. There's something almost primal about growing your own; the smell of the leaves, the anticipation of that first ripe fruit, the satisfaction of eating something you've nurtured from a tiny seed.
April is the month it all begins in earnest, and if you get your tomatoes right now, you'll be rewarded come July and August.
Choosing Your Variety
Before you even think about compost and pots, spend a little time on variety selection, it's one of the most enjoyable parts of growing tomatoes and one of the most overlooked. For beginners, cordon varieties like Gardener's Delight or Alicante are reliable, productive, and forgiving. If you're short on space, try Tumbling Tom or Tumbler, both of which do brilliantly in hanging baskets or window boxes. For something a bit more exciting, Sungold produces extraordinary orange cherry tomatoes with an almost tropical sweetness, while Costoluto Fiorentino gives you those knobbly, ridged fruits that look magnificent on a plate.
The key thing to remember is that most outdoor varieties will struggle in a British summer without some shelter or luck, so if you're growing outside, stick to tried-and-tested varieties rather than chasing the exotic.
Sowing in April
If you didn't get round to sowing in March, don't panic, April is actually a perfectly sensible time to start tomatoes from seed. Sow into small pots or module trays filled with good quality seed compost, planting two seeds per cell at a depth of around half a centimetre. Water gently and place somewhere warm: a heated propagator is ideal, but a sunny windowsill works well too. Germination usually takes between five and ten days, depending on temperature.
Once seedlings emerge, thin to the strongest plant per cell and keep them somewhere bright and warm. The biggest mistake at this stage is letting them get leggy through lack of light, if your windowsill isn't bright enough, a grow light will make a real difference.
Getting the Roots Right
This is where many home growers lose out without realising it. Young tomato plants need consistent moisture without sitting in waterlogged compost.
Too wet and the roots suffer; too dry and growth stalls. Placing a Hortiwool Garden Pad beneath your seed trays helps regulate moisture at the root zone, releasing water gradually rather than flooding or drying out. As the wool slowly breaks down, it also releases small amounts of nitrogen, a nutrient tomatoes are particularly hungry for. It's a simple addition that makes a meaningful difference, especially in the early, critical weeks of growth.
Potting On your Tomatoes
Once seedlings have their first set of true leaves, the serrated, distinctly tomato-scented ones that follow the initial seed leaves, it's time to pot them on into individual 9cm pots.
Use a good peat-free compost and bury the stem a little deeper than it was before. Tomatoes are one of the few plants that will actually put out roots along any buried stem, which means a deeper planting encourages a stronger, more extensive root system.
From here, pot on again as roots fill the container, aiming to get plants into their final position, greenhouse border, large pot, or grow bag, by late May or early June once the risk of frost has passed.
Common Problems to Watch For
Damping off is the enemy of young tomato seedlings. It's caused by a fungal pathogen that thrives in cool, damp, stagnant conditions and can wipe out an entire tray overnight. Good air circulation, avoiding overwatering, and clean equipment are your best defences.
Leggy seedlings, as mentioned, are usually a light problem. Move them closer to a window or supplement with artificial light rather than trying to prop them up.
Pale, yellowing leaves at this stage often indicate the seedlings have exhausted the nutrients in their seed compost and need potting on into something more substantial.
The Bigger Picture
There's a reason tomatoes are the nation's most popular home-grown crop. They're generous, they're versatile, and when you get it right they're incomparably better than anything you'll find in a supermarket. April is your starting gun. Get the conditions right, pay attention to moisture and light, and you'll have plants that will carry you through the entire summer. Always remember to use Hortiwool Garden Pads to help protect seedlings, retain moisture and deter pests.
Happy growing. 🌱