If you don't have room for a greenhouse, but want to grow under glass, a mini greenhouse is the ideal way to extend the growing season. There's a variety of sizes, prices and styles, so you're sure to find one that suits your space and wallet.

So what is a mini greenhouse?

There's several categories, each with their pros and cons:

A tomato house (mini growhouse or growhouse) is cheap, made from push-together steel framework covered by a uPVC zipped cover. However, they're light and can blow away. Shelves can also bow under weight, so these are best for growing a small number of tomatoes in sheltered areas.

An aluminium or wooden-framed mini greenhouse is more expensive, usually catering for one growbag. Despite their small size, they are strong, can be fixed to walls and are adaptable, with shelving and a top glazed lid.

A cold frame is excellent for hardening off crops. Lighter versions are great for warming soil in spring. Heavier wooden types can be expensive.

With planning, an unheated mini greenhouse can be productive all year.

Seasonal growing

In spring, germinate vegetable seeds such as kale, chard, spring onions and salad crops, especially if you have a cold clay soil. 'Baby' carrot varieties can be sown in sandy soil in pots to evade carrot root fly.

Onion sets can be started off in modules to plant out in April. Growing on plugs from garden centres is a cost-effective way of producing plants.

By the end of May, Mediterranean crops such as tomatoes, peppers, cucumbers or aubergines can be grown in a growbag – make sure your mini greenhouse has removeable shelves, as they'll need the height. They'll occupy the space until the beginning of October.

There's still warmth in the autumn sun, so you can strike Fuchsia and Pelargonium cuttings. Winter salad crops such as leaf mixes, cut-and-come-again lettuce and rocket can be sown. Vegetables such as spring cabbage, brassicas and broad bean Aquadulce Claudia can be grown from seed and overwintered, as can sweet peas.

During winter, tender plants can be stored, as long as it remains frost-free. Bulbs, such as Narcissus Paperwhite can be forced for Christmas flowering.

You must remember ventilation. As the house is so small, it heats up and cools down rapidly. Big temperature change are death to young plants – two vital pieces of equipment are a maximum/minimum thermometer and an automatic vent, which can be attached to some frames. If not, two alarm calls a day will remind you!

Lack of ventilation will also lead to rots and mildews, which spread rapidly in a confined space.

Cleanliness is a must – remove all dead plant material promptly and check for pests at least twice a week.

Spend the extra on toughened safety glass, not horticultural glass. It is extremely strong and breaks into harmless pieces – horticultural glass is thinner and smashes into shards.

You do get out of an activity what you put in, literally true of a mini greenhouse. For a little regular effort, you could be enjoying the fruits (or veg) of your labours.