What to grow in a greenhouse in winter

We have all wondered before about what plants will grow in a greenhouse in a UK winter. Note for this article, I am just talking about unheated greenhouses.

If you plan on heating your greenhouse then obviously you will be able to grow an even wider variety of plants.

One key thing to remember is that plants won't grow as quickly in winter as they do in spring and summer. The winter gardener has to be a patient gardener!

Some plants may not ever make it to full development when grown over winter, but they can still be harvested and provide a delicious winter bounty.

There are lots of different plants you can grow, and some will do better some years than others depending on the severity of the winter. However, the plants I am going to list below are some of my favourite plants to grow over winter.

So if you have ever wondered what to grow in a greenhouse in winter then check out my recommendations below.

Potatoes

Potatoes can be grown overwinter in a greenhouse using pots, buckets or even the ground if you have raised beds or just an earthen floor.

When growing potatoes in pots it is essential to use as larger pot or tub as possible. Half fill them with soil, plant your potatoes then cover. We recommend one or two potatoes per container depending on the size.

You can use the method that Monty Don does on gardeners' world when growing container potatoes. Fill the pot about a third full with compost. Place your potatoes on top of the compost and then just put enough compost in to cover them.

As the potatoes grow you keep adding compost on top of them until you reach the top of the container. This is how you can still "Mound Up" container-grown spuds as you would for ones grown in the ground.

Carrots

Carrots can be grown over winter if planted in autumn; we have a full article here on how to mulch carrots for winter.

Again you could grow your carrots in the greenhouse provided you either have beds in there or use containers. I like to grow carrots in containers anyway as you can ensure there is really loose soil that way so you get nice straight roots.

If you want to use containers but don't want to buy a load of pots then I recommend these canvas bags, they are relatively cheap and do the same job and can be folded up and stored away when not in use.

If you are looking for a carrot to grow into winter then Autumn King is a really good choice.

Swiss Chard

Swiss chard is a tough plant and could survive outdoors over winter; the problem is it wouldn't grow much in those conditions. If you want to harvest and regrow some leaves then it needs to be in a greenhouse.

The milder conditions will allow the plant to grow, meaning you can harvest some of those beautiful, bright stems. The growth will still be slower in winter, but in a greenhouse it will still grow at least!

Spinach

Spinach is a vegetable that thrives in the cold. You can harvest Spinach almost all winter long, particularly when using a greenhouse. Couple that with the fact that Spinach is quick-growing and you can really see why it is a popular wintergreen.

Giant Winter is a good variety to pick for over winter growing. This large-leaved spinach is cold hardy and can be grown outside but would need fleece protection in the middle of winter.

Grown in a greenhouse though this spinach would be fine all winter long and can provide hearty green leaves for you and your family when there is precious little else growing.

Garlic

You can start garlic off in your greenhouse early in the new year. You can then think about moving it outside in early spring. As soon as the soil is soft enough to be dug, you can transplant your garlic out of the winter greenhouse.

Garlic actually needs a period of really cold weather to properly develop. it is a frost that actually starts the formation of individual cloves, garlic grown in warmer months with no frost usually develops as one single massive clove.

Lettuce

Lettuce is a great vegetable to grow in the greenhouse over winter. Lettuce is very cold tolerant, and some varieties are also frost resistant.

There are lots of different lettuce types suitable for growing over winter but I really like to grow loose-leaf types at this time of year.

You can begin harvesting these really early and don't have to wait for a head to form.

Kale

Kale is an ideal plant to overwinter in your greenhouse and actually improves in flavour after being exposed to really cold weather.

A type I like to grow over winter is Siberian Kale, as you can probably guess from the name, this is one tough plant.

Getting your greenhouse ready for winter

Heaters

There are lots of different types of heaters you can use in your greenhouse over winter. If you have power in your greenhouse, I really like these tube heaters. They are efficient to run and can keep your greenhouse from freezing on those icy winter nights.

Recycled Plastic Bottles

This is a great little trick to help keep heat inside your greenhouse in winter. Get an old plastic bottle and paint it black and fill it with water. Due to the black paint, the water will absorb the suns heat throughout the day and then slowly release this heat throughout the night.

Seed Pads

These heated pats sit under your seed trays and keep them toasty. A great way to provide targeted heat to specific plants.

Lights

The only issue with winter gardening is not just the temperature but also the lack of daylight. Fear not though, for if your greenhouse has power, you can get LED grow lights. These lights provide all the light your plants need to grow and can make up for the lack of sunlight we get here in the UK on winter days.