APRIL IN THE GREENHOUSE

Now the most exciting time of the season begins

April is a lovely time in the greenhouse. There’s a quiet energy, a sense of steady momentum. The rush of sowing is in full swing, but it’s still early enough to feel peaceful. The days are longer, the sun is gaining strength, and everything starts to feel just that bit more alive. In my own greenhouse, there’s a comforting rhythm—clearing the old, making space for the new, and tending the things that have quietly carried on through winter.

Overwintering peas in a greenhouse – simple and rewarding

One of the joys this month is picking the first of the 'Douce Provence' peas. These were sown back in November, straight after the tomatoes came out. They’ve been tucked away in the unheated greenhouse all winter, slowly growing without fuss. Unlike peas grown outside, there’s been no need for netting to fend off pigeons. It’s one of the small but satisfying rewards of greenhouse gardening. The plants aren’t particularly tall, but they’re full of flower and beginning to crop now. I like to pick them young, when the peas are sweet and crisp. They rarely make it to the kitchen, most get eaten right there and then as I potter about.

Growing peas through winter in the greenhouse has become a bit of a quiet ritual for me. There's something heartening about seeing those first green shoots in the cold, still days of December. While outside beds are resting under frost or even snow, inside the greenhouse, the peas carry on slowly, steadily. Because temperatures stay just a few degrees warmer under glass, the plants can keep ticking over. I don’t mollycoddle them either, no heat, no grow lights. Just a little shelter from the worst of the weather. Once they’re about 10 cm (4 inches) tall, I give them some twiggy hazel sticks or support  to climb and let them get on with it. By March, they’re usually covered in tendrils and buds, and come April, the first proper harvest begins. They’ve filled a space in winter when little else was happening and given a cheerful, edible return for very little input. Elsewhere, it’s time to say goodbye to the overwintered crops. The troughs have been a steady source of food through the colder months, with mustard leaves, lettuces, pak choi and miners lettuce filling the gaps. But now, with longer days and warmer temperatures, they’re starting to flower. That’s the sign it’s time to clear them out. Nothing is wasted—the edible bits have been used and the rest has gone to the compost heap. It feels good to close that chapter and prepare the space for spring and summer plantings.

Clear away winter crops

When I clear the troughs, I take the opportunity to refresh the soil. I remove about a quarter of the compost and soil mix, making room for some topsoil and a good helping of well-rotted manure or homemade compost. This brings a bit of structure back to the mix and adds fresh nutrients for the season ahead. I also like to mix in a handful of slow-release organic fertiliser. It gives things a gentle boost without being too rich. The soil in containers and troughs can get tired, especially after feeding crops over winter, so this little bit of extra effort now really pays off later.

Refreshing the soil for the new season

I’m a big believer in homemade compost. There’s something very grounding about the cycle, kitchen scraps, garden trimmings, even those cleared out flowering mustard greens, all going back to feed the next crop. When it’s well-rotted, dark and crumbly, I know it’ll bring life back into tired soil. I use a garden sieve to take out any big lumps or woody bits before mixing it in. If you’re using shop-bought compost or manure, just make sure it’s fully broken down. Anything too fresh can be a bit too strong and might scorch young roots. After working it all in, I give the surface a good rake and leave it to settle for a week or so before planting.

Ventilation strengthens the plants

As the days warm up, seedlings in modules will start growing more quickly—and they’ll also start drying out faster. It’s worth checking them once or twice a day now. I give them a little water from a fine-rose Haws can, just enough to keep the compost moist but never soggy. Overwatering is just as risky as underwatering, especially when plants are still small and their roots delicate.

There’s also something to be said for using the warmth of the day wisely. If the sun is out and the greenhouse is warming up nicely, I like to open the doors and vents for a good bit of airflow. It helps toughen the seedlings and keeps mould and damping off at bay. But with those open doors comes a new challenge—inquisitive birds. I’ve had the odd blackbird or robin hop in, nosing around for worms and sometimes digging up freshly sown trays in the process. A bit of fleece or netting draped over your seed trays can save a lot of heartache.

And if you’re anything like me, you might find the odd tray has dried out more than expected on a warm day. Rather than drowning it in water, I place the whole tray in a shallow tray of water for half an hour. It allows the compost to take up moisture slowly and evenly, and it’s far gentler on those emerging roots.

If you have heat in the greenhouse, or a propagator, now is the perfect time to sow courgettes and sweetcorn. These are warm-weather crops, so they don’t need to be rushed. I usually sow mine in mid to late April, aiming to plant them outside around mid-May, once the risk of frost has passed. They grow quickly once they get going, so there’s no need to be too early. Starting them indoors gives them a good head start without the risk of the cold stunting them.

Start the new season with a calm approach

Now’s also the time to start getting everything in place for tomatoes, chillies, aubergines and other hot crops. I find it helps to treat this like a spring clean. I sweep the floors, clear out any old compost bags or broken pots, and move what I need into place. I check the canes and strings I’ll use for support, and give my trusty pots a good wash. If you’re reusing growbags or troughs, make sure they’re in decent condition and top them up with fresh compost or soil where needed.

This month is about setting the stage. The greenhouse doesn’t burst into life all at once, but it’s definitely stirring. Every little job done now is a step towards the abundance of summer. Whether you’re tending tiny seedlings or harvesting the last of your winter greens, there’s a quiet satisfaction in being present in the space, listening to what it needs, and responding in kind.

So take your time in April. Let the sunshine warm your back as you sow and pot on. Enjoy the crunch of fresh peas straight from the vine, and don’t rush the transition. The greenhouse is a place of patience as much as growth, and April is when that balance really shows itself.

Happy gardening.