Even an unheated greenhouse can significantly extend the growing season of edible crops. Here are some of the ways you can successfully grow crops all year round in your greenhouse.
Perhaps the main point of owning a greenhouse, is to help site, sustain and prolong the growing of your plants and flowers. But of course, a greenhouse can also serve to extend the growing season of your home grown edible crops – fruit and vegetables that would otherwise struggle to survive past the late autumn months or grow and flourish during the chilly early spring.
Protecting From Frost
If you want to grow crops all year around in your greenhouse you’ll need to take measures to protect your plants from frost. In a heated greenhouse, this is a much easier task. However, even half hardy plants left to overwinter in an unheated greenhouse may still be susceptible to frost damage.
There are a few options you can choose from to protect from frost in your greenhouse; firstly, you can insulate the greenhouse with clear bubble wrap. This not only insulates the greenhouse glass and helps to trap heat, but also allows light to filter in, which is especially important as the autumn and winter nights draw in. Of course, you can maximize ‘daylight’ hours via artificial lighting, but for some this could prove tricky to install and perhaps a little costly.
Another option to prevent frost in your unheated greenhouse is to install a portable heater. For maximum cost and fuel efficiency, this could be left on minimum during the night time when the risk from frost is greatest. Of course, insulating your greenhouse in addition to heating is an even better solution!
Heated propagators are also pretty essential to growing crops all year round in your greenhouse, as the propagator will help to speed germination before the ambient temperature inside the greenhouse reaches the necessary level.
What Can I Grow All Year in My Greenhouse?
It’s not about finding one wonder-vegetable or fruit that will crop all year round, it’s about finding an assortment of edible crops that can be overlapped, changed and rotated as the seasons melt into one another. Your best bet is to start with planning what you would like to grow, and when each crop’s general growing seasons are. Remember you’ll need to opt for half-hardy varieties of fruit and vegetables. Think about what you’ll benefit from picking fresh, as space in your greenhouse is at a premium.
Winter
Many people think of winter as a ‘quiet time’ in the growing calendar. And although it’s true that crop production does slow significantly during this season, it doesn’t have to stop altogether.
In early winter, you can already start thinking ahead to next season by planting early carrots. Rather than growing in pots or straight into the ground, try growing them in grow bags that have been used during the previous growing season. If you’re after continuous cropping of carrots, you can sow another row of carrots around mid-winter.
Early to mid winter is also a great time to get your module seed trays out and start sowing a variety of salads and leaves – little gem lettuces, Winter Density or Bubbles lettuce are all potentials. During this time you can also start to think about chitting early potatoes, although it’s best to take extra measures to protect them from frosts – place them in egg boxes and insulate fleece or alternatively keep them under an unheated propagator may help in this regard.
If you have a heated propagator, you could also try sowing early cabbages, leeks, Brussels sprouts and summer cauliflowers in module seed trays or biodegradable paper pots.
Spring
Get into the swing of spring by sowing more summer lettuces and cabbages in module seed trays. You can also start to harvest your first crops of lettuce that you sowed during the winter, whilst you sow modules of your first tomato plants. During spring your greenhouse can also become host to onion and shallot sets – simply take a shallow tray, fill with soil and keep moist and warm.
Mid-spring is when you can start to think about getting the heat-loving crops started, such as sweetcorn, peppers, melons and cucumbers. During mid to late spring your tomato seedlings should also be large enough to prick out and re-pot accordingly.
Summer
Spring and summer are traditionally the seasons when the greenhouse is in full swing. In addition to the usual crops of tomatoes, peppers, melons and other heat-loving plants that remain inside your greenhouse during the hot, long days, you’ll find that this season is when you can start off your herbs for overwintering.
Autumn
Outside of the greenhouse, autumn is a season of plenty. However, while outside the greenhouse, other plants are in full fruit or coming to the end of their summer cropping peak, things inside the greenhouse will probably be coming to their season’s end. Whilst you’ll still be harvesting from your fruit and vegetable plants, this is the time to think about clearing out and cleaning up, ready for overwintering and the sowing of next season’s early produce.