Start With the Crops You Actually Eat

The quickest way to waste money on a kitchen garden is to grow things your household won't eat, or things that cost pennies in the shops. Before you buy a single seed packet, spend a week noting what actually disappears from your fridge. If you get through bags of salad leaves, bunches of herbs and punnets of cherry tomatoes every week, those are your priorities. If parsnips languish in the drawer until March, leave them out this year.

The maths is simple. A packet of salad leaf seed costing a couple of pounds can give you cut-and-come-again harvests from spring right through to autumn, while a single supermarket bag of the same leaves costs more than the packet. Herbs are even better value, because you buy them once and then divide, take cuttings or let them self-seed. Focus your budget where the savings are biggest, and treat everything else as a bonus.

Choose High-Value Crops for Small Spaces

In a small garden or a few pots on a patio, every square foot has to work hard. These crops earn their keep:

• Cut-and-come-again salad leaves — sow in a trough or old washing-up bowl and snip with scissors rather than pulling whole plants. You'll get three or four cuts from one sowing.
• Cherry tomatoes — one plant in a large pot or grow bag can crop for months. Choose a bush variety if you don't want to fuss with supports and sideshooting.
• Climbing French or runner beans — grown up a wigwam of canes, they take up almost no ground space and crop heavily over a long season.
• Courgettes — two plants will feed a family, but be warned: by August you may be leaving them on neighbours' doorsteps.
• Chard and kale — cut the outer leaves and the plant keeps producing, often right through a mild winter.
• Herbs — basil, parsley, mint, thyme and chives. Buy one pot from a supermarket, split it into several pots, and you have a year's supply for the price of a single shop-bought bunch.

Skip maincrop potatoes, onions and brassicas that need a long season and lots of room. They're cheap to buy and hungry for space you don't have.

Build Free Fertility With Home Compost

Healthy soil is the foundation of everything, and the cheapest way to get it is to make it yourself. A simple compost heap made from four pallets tied together at the corners will handle everything your kitchen and garden produce. Aim for roughly equal volumes of green material — grass clippings, vegetable peelings, tea leaves, spent annuals — and brown material such as torn cardboard, scrunched paper, dry leaves and woody prunings.

Turn the heap every few weeks if you have the energy, or simply leave it for six to twelve months. Either way, you'll end up with dark crumbly compost that improves pots, raised beds and borders alike. Autumn leaves stuffed into an old bin bag with a few holes punched in it will rot down into leafmould within a year — superb for mulching and for mixing into potting compost.

If you keep just one thing in mind, make it this: feed the soil, not the plant. A garden with good homemade compost needs far less bought fertiliser, and plants grown in it shrug off pests and dry spells much better.

Reuse Containers Instead of Buying Them

Almost anything that holds soil and has drainage holes will grow a plant. Old buckets, trugs, mushroom trays, broken crocks, plastic storage boxes, even sturdy shopping bags lined with a bin liner — all of them work. Drill or punch holes in the base if there aren't any, and raise containers on bricks or pot feet so water can escape freely.

• Deep pots for tomatoes, courgettes and beans — aim for at least 30cm of depth.
• Shallow trays for salad leaves, radishes and herbs.
• Old guttering fixed to a wall makes a brilliant trough for peas and salad.
• Yoghurt pots and loo roll tubes for raising seedlings — free, and they break down in the soil.

Wash anything that held food before using it, and avoid containers that once stored chemicals or paint. Soil-wise, a mix of two parts home compost, one part leafmould and a handful of grit or sand per pot will serve most crops well without buying specialist mixes.

Plan for a Longer Harvest

One of the joys of a small productive garden is that you can keep it cropping for most of the year with a little forward planning. Sow salad leaves and radishes in small batches every three weeks from March to September rather than all at once — you'll have a steady supply instead of a glut followed by nothing.

Use walls and fences for climbing crops, and tuck quick growers like rocket and land cress between slower plants. After you lift a crop, don't leave the space bare: scatter a green manure such as field beans or phacelia, or pop in a fast autumn salad. Save seed from your best beans, tomatoes and lettuces at the end of the season, and swap with neighbours and allotment holders — it's the cheapest way to widen your variety without spending a penny. A little planning now means fresh, home-grown produce on your plate for far less than you'd pay at the shops.