Greenhouse effect
WINTER IS ON ITS WAY, SO NOW IS THE TIME TO PROTECT YOUR PLANTS AND SOW THE SEEDS OF A RICH HARVEST UNDERCOVER
A QUIET half hour spent pottering in the greenhouse is one of life’s treats, especially in winter. There’s lots you can grow, even without heating, so why leave the space empty?
All sorts of salads and vegetables will grow in the soil border to give you some early crops. Just pull out your old tomato plants, clear away the debris, then fork some organic matter into the border and you are ready to go.
It takes a bit of organising, but there’s nothing like some worthwhile winter gardening to double the use you make of your greenhouse.
WINTER VEG
Sow a row or two of ‘ Winter Lisbon’ now and you’ll be pulling spring onions from March onwards. You can also grow calabrese undercover.
Sow it now where you want it to crop, thin out the seedlings (don’t transplant them) and you’ll have perfect heads ready to cut in April or May.
Another crop that does very well is mangetout peas. Sow ‘Oregon Sugar Pod’ now, letting the plants scramble up netting as they grow four feet tall, and you’ll be picking from late February until May.
If you have young plants of an overwintering cauliflower, such as ‘All The Year Round’ or some ‘Hispi’ cabbage seedlings, transplant them now and you’ll be eating the crop around April or May after most of your outdoor winter vegetables have ended.
SUPER SALADS
As for salads, a few varieties of lettuce, such as ‘All Year Round’ and ‘Arctic King’, can be grown under glass in winter.
Sow them now in rows, thin them out and they’ll be ready in spring – if you’re lucky. It has to be said that winter lettuce is one of the hardest crops to grow as it’s a martyr to mildew, so I’d grow lambs lettuce (corn salad) instead.
Sow a row or two now a couple of inches apart and you’ll be picking the small rosette-shaped plants to use around Christmas. Meanwhile, the seedlings you remove as you thin the rows make a good extra to go with baby salad leaves.
As corn salad is so small and ground-hugging it pays to sprinkle the soil thickly with horticultural vermiculite or silver sand after sowing so the plants grow on a clean, well-drained base. It makes for a higher quality harvest and less washing and trimming of leaves.
FLORAL FANCIES
If you don’t fancy growing veg or salads, sow some hardy annual flowers. The ones I’ve found most reliable are marigold, larkspur and taller varieties of candytuft.
Sow them in generously spaced rows, then thin the seedlings out and you’ll be cutting next spring.
If your greenhouse has staging, it’s invaluable for potted plants in winter.
Dwarf spring bulbs are stunning under cover and there is still time to plant tulips, crocus, ipheion and fritillaria.
Use a gritty compost made by mixing John Innes No2 potting
compost with about 10% potting grit.
They will flower in early spring and you can enjoy them in comfort and in perfect condition since the fragile petals will not have been bashed by bad weather.
Alpines are another star for winter greenhouses. Although they don’t need protecting from cold, they appreciate being sheltered from rain which rots them.
Pots of evergreen sempervivums and silver-encrusted types of saxifrages are a good choice as they have contrasting shapes and colours for year-round interest, and all sorts of little “cushion plants”, including mossy saxifrages, flower early in spring under glass.
But for showy winter flowers, try your hand at hardy cyclamens. They flower at various times from autumn until spring and some have beautifully marbled or variegated leaves.
A small selection of winter and early spring alpines is a good investment and it’s very practical as the plants go outside from April to the end of October, which leaves you room to grow all your regular greenhouse favourites in summer.