I'M the first to admit I've made costly mistakes in my garden over the years.

I've planted specimens in the wrong place, made impulse buys at the garden centre of impractical plants which weren't going to survive in the frost pocket where I live and bought pretty pots that didn't go with my house or my existing collection.

But now I've opened gardener Alex Mitchell's new book, Gardening On A Shoestring, which gives budget-conscious gardeners some ideas on how to save money, all that waste is in the past.

"We've all done it - stumped up on plants, tools and endless bits of plastic kit and then thrown them at the garden in the hope that they will miraculously organise themselves into something beautiful," she says. But you don't need all that clutter to be a successful gardener.

Here's a few of her tips on how to create a garden on a budget:

Make seedy savings: Many plants grow easily from seed, including sweet peas, cosmos, flowering tobacco, cornflowers and Californian poppy. A packet containing around 100 seeds can cost you a fifth of the price of one plant. From mid-spring to early summer, just scatter them directly on to finely-raked garden soil in a sunny spot, rake them in and water well.

Club together: If you're buying online, group your purchases with friends to save on postage costs and look out for bargains if you order a multiple of one specific plant.

Garden centre or car boot?: Don't rule out cut-price pound stores and car boot sales, which often have good plants for much less. When buying plants, don't buy the ones already in full flower. Look for those with unopen flower buds or wait until the end of summer to buy shrubs and perennials, when garden centres discount their stock. Autumn is also a good time for planting.

Pots for a pittance: Use your imagination. Upcycle old containers such as tins, bowls and colanders to give your garden instant character. If you want to go big and brazen, brightly coloured plastic tub trugs can make good flower and fruit containers. Alternatively, ask your local deli for huge empty tins which have held olive oil, or other vintage tins, taking off the labels and letting them rust naturally. Just drill holes in the bottom of them.

Be waterwise: Instead of investing in an expensive automatic irrigation system for your potted plants, save your old one-litre plastic bottles, discard the lid, cut off the base of the bottle and push it lid end down into the compost beside your plant. When the bottle doesn't fall over, it's deep enough. Fill it with water and it will drip out gradually, direct to the plant roots.

Thrifty Topiary: If you want to recreate the effect of topiarised box, use a different plant. Ilex crenata, or Japanese holly, looks almost the same as box and can be pruned in the same way, but tends to be more affordable and won't suffer from box blight, a disease which can wipe out box in a flash.

Hedge your bets: If you want to create a hedge, take advantage of bare-root offers at the end of the planting season (which runs from winter to early spring). Good offers tend to come up towards the end of winter when nurseries are trying to get rid of their bare-root stock.

Pave the way: If your urban garden has an old concrete path you want to renew on a shoestring, be warned that the cost of breaking it up and removing it may be high. If the concrete is sound, you can lay paving stones on top of it, or alternatively use tiles, laying them on a layer of mortar or a resin bonding adhesive.

Gardening On A Shoestring by Alex Mitchell is published by Kyle, priced £16.99. Available now.

BEST OF THE BUNCH – Perennial wallflower (Erysimum)

These pretty perennials do not need replacing every year like their biennial counterparts, and nearly all are evergreen. They thrive in sun and on well-drained soil enriched with organic matter. Trim them after flowering to remove faded flowers and straggly shoots and keep them neat. Good varieties include E. 'Bowles' Mauve', which grows to around 75cm (30in). Its spikes start flowering in March and peak in April, but then it flowers intermittently until late autumn. Place it with silver-leaved Mediterranean-style plants and dwarf bulbs and you won't go far wrong. Other good varieties include the compact, low-growing E. 'Wenlock Beauty', whose copper flowers fade to mauve, while 'Plantworld Gold' produces gold flowers which age to purple. Erysimum don't last forever, though. They will need to be replaced around every three years.

GOOD ENOUGH TO EAT – Creating a new asparagus bed

This luxury vegetable which used to only be available in late April and May but now seems to be in supermarkets all year round may take a little work initially but you should reap rich rewards for years to come. An estimated 10 established plants should yield around 3kg of spears over a six-week period annually for up to 20 years. The easiest way to start a bed is to buy the crowns - dormant bases of one-year-old plants - in April. They need to be planted in well-drained, neutral or slightly alkaline soil with plenty of added well-rotted organic matter, allowing 45cm between plants and 90cm between rows. Dig a trench wide enough to spread the roots out and lay the crown gently on a mound in the centre of the trench with roots spread on either side. The top of the crown should be around 13cm below the soil surface. Cover with loose soil. You need to be patient as the spears aren't harvested for the first two years after planting the crowns. When you do start to pick, do it from late spring until early summer, when the plants should be left to build next year's crop.

WHAT TO DO THIS WEEK

  • Begin to harden off young plants and overwintered cuttings.
  • Remove insulation from the greenhouse.
  • Apply spring fertilisers, weedkillers and mosskillers to established lawns.
  • Prune tender climbers and wall shrubs before leaves open fully.
  • Plant summer hanging baskets and windowboxes but keep under cover until all danger of frost has passed.
  • Plant up herbs in containers.
  • Cut back old hydrangea flowers to a healthy pair of buds.
  • Lift and divide congested perennials such as campanulas and monardas.
  • Sow peas, carrots, parsnips, lettuces, spinach, Brussels sprouts and kohl rabi outside.
  • Sow seeds of tomatoes in a heated propagator or on a warm windowsill, to grow on outdoors when all danger of frost has passed