Sweet Pea need some sunshine. If you can't put them where the sun will light them directly for at least a couple of hours on a sunny summer's day, to avoid disappointment grow something else. They don't grow well if their soil is often waterlogged: apart from that, they are not too choosy. You will want a site sheltered against the worst summer winds, so as to avoid damaged blooms.

Soil. Tall-growing Sweet Pea do appreciate being able to root down just a few feet, but they don’t expect you to do the work for them. Merely forking through the top spit a couple of times to develop a good tilth will produce satisfactory results in most gardens. Beware of giving Sweet Pea indigestion with too much organic matter or nitrogen-rich fertiliser, which produce lots of leaves but few flowers. For best results, breaking up a second spit and incorporating a little leaf mould or well-rotted compost would be ideal, enriched with no more than 50 g/sq m of potato fertiliser. The top spit should lie rough through winter frosts, and be cultivated to a fine tilth while incorporating a generous helping of a soil conditioner two or three weeks before planting out. If sowing in autumn, your site must be ready to receive the plants in March, so you will probably need a plastic cover over it after final site preparation late in February.

Support. Sweet Pea must have something to hold on to. They do very well on chicken-wire (50 to 100 mm mesh) or sheep-wire. Plastic netting is almost useless unless tightly tensioned and stiffened with bamboo uprights no more than a metre apart. Our varieties will grow 2 to 3 metres high, but 2 metres is enough for most of the old-fashioned sorts. The ideal support is made of twiggy birch branches cut after leaf-fall, arranged either in a circle or a line. These are favourites because they are wider at the top, where the Sweet Pea plant branches widely too. Hazel is a second favourite, stiffer but lacking the multitude of fine twigs. The trouble with wigwams is that they are narrow at the top. If you want to use a wigwam, try making the sticks cross half way up so that they spread out at the top. You need to get your supports installed and totally wind-firm just before planting out.

Warfare. The other basic preparation is to decide how you are going to succeed in keeping slugs and greenfly away throughout the season, and rodents away from seed and baby plants. Dedicated no-chemicals gardeners, please take this very seriously.

Selection. The short and knee-high kinds of Sweet Pea are not suitable for most parts of Ireland, as they generally require more heat and light than our damp areas can provide. For strong sweet scent there's nothing to beat the old-fashioned ones that are often now labelled Grandiflora or Heirloom varieties. They are fine for scenting the garden or making a posy, but the flowers are small and plain-shaped and the stems are rather short. The Multiflora kinds have more than five flowers per stem: these can make a good show in the garden but have limited use in the house because the bottom flower falls before the top one opens, and the individual flowers lack refinement. The Spencer peas that we work with have much larger, frillier flowers, generally four of them per strong stem in a wider colour range. Not all modern Spencer varieties are strongly scented but virtually all the whites, creams, blues, and lavenders are.

Sowing time. For the best crop, October is best, Early November or Late January second best, February and March good, early to mid-April is not too bad, but May is no good - you miss half the season. Plants sown in autumn or winter must have the protection of a sun-lit cold-frame or an unheated but sunny glasshouse. Given good weather, the best flowers with longest stems begin two or three weeks after flowering starts, and gradually deteriorate after two or three weeks at their peak, so if you want flowers for an August wedding March is better than October.

In Spring you can sow directly where the plants are to flower as soon as a sun-lit site is ready. However, if there's no sunlight there at ground level in March, it's best to sow in deep trays or root-trainers (for spring sowing use the smaller size that has five cells to a unit) and stand these in a sunnier spot until you plant out a few weeks later on, when the sun rises higher. Open ground for direct sowing needs to be brought to a fine tilth at least 10 cm deep, and to be moist but not wet at sowing time.

Germination. Germinate enough seed to allow for a few casualties and plan for at least 15 cm between plants. If your soil is rich they can be further apart. Seed is cheap: I would germinate 25% more than the number of plants I wanted to grow. You can use perfectly safely a seed that has a split seed-coat – and it won’t need chipping.

Don't listen to anyone who says you shouldn’t wet Sweet Pea seed before germinating it. Such poor advice may have arisen from the experience of people who submerged their seed for too long. You should germinate pre-wetted seed on a moist, sterile antiseptic-free surface (use tissue, cloth or cotton-wool) and keep it damp at room temperature or not much below (65-68 deg F). Cover fairly airtight so that their atmosphere becomes saturated. Darkness isn't essential. The coat of any seed that hasn't swollen after 24 hours must be chipped to let moisture in. Make a nick opposite the scar where the seed was attached to its pod. I use nail-clippers to nick the seed-coat, but a file is OK, even a sharp wee knife can be used. After nicking, put the seed back straight away. After the seed has been four days in the damp, look it over every day and sow all that have the root-tip showing through the seed-coat.

Sowing. Sow germinated seed into the open ground, 9-cm pots, root-trainers (use the largest size for autumn sowing), or a deep seed tray. You can use one seed-tray for all the seed of each sort, and transplant later, or sow individually at this stage. Do not sow several plants in one container if they are to remain together until planting time: the root damage that occurs when untangling for planting checks growth and invites disease. A general-purpose peat-based compost is suitable for late January or spring sowing, but loam-based genuine John Innes No 1 compost is best for plants that have to stay in their pots from Autumn until planting-out. Avoid composts that contain coir or other fibres, because they make it difficult to spread the roots when you come to plant out. Except in the seed-tray, all compost needs to be fortified with 3 g/litre of slow-release Vitax, Osmocote or MiracleGro Shake and Pour. Sowing-compost needs to be just moist enough to hold shape when squeezed, moist but not wet. The sprouting seed should be covered 15 mm deep but not much more: that is deep enough to anchor the root and steady the emerging shoot.

Potting-on. If you use the seed-tray approach for autumn sowing, pot on into the fortified compost when the plants have two pairs of leaves, and nip the tip of the main root at the same time. That will give a nice branchy root structure.

Growing on. The hardier the plants are, the better they'll flower when summer comes. That means they need maximum light and air. Through the winter and early spring, give the plants all you can, so long as they aren't deeply frosted. Let them thaw slowly in the dark if the compost freezes at all. Well-hardened October-sown plants will withstand five Celsius degrees of frost well so long as you thaw them slowly. Winter-sown plants in their early stages are checked by more than a degree or two of frost. Only close down the cold frame or glasshouse if frost is likely, and open up as soon as the risk has passed. It’s good to let light showers do your watering, but leave the cold-frame glass over the plants to prevent heavy rains from leaching the nutrients out of the compost. Prop it up to make a gap at least 5 cm high all the way round, then tie it down to cleats on the cold-frame unless you are gardening in a very sheltered locality. When your plants have four pairs of leaves, nip out the top bud. This nipping has two purposes: it causes basal shoots to break out if they haven't already, and it prevents extension to form tendrils that would tangle plants together.

Planting out. You should get the plants into their final position before the basal shoots are 15 cm long - 10 cm is better. Spread the roots out a bit to give the plants a better "take". The newly set out plants will need something low to hold on to and stop them swivelling in the wind. Bushy twigs (birch again) 20 to 30 cm long poked in beside the plants do well, but poke some short bits in between the shoots as well. When the root-tips have started their work and the shoots begin to grow upwards, a few ties will be necessary to lead them up the supports. Soon new leaf-pairs will be equipped with vigorous tendrils: these quickly grasp the supports in briskly breezy weather, but will need your help in calm conditions.

Flowering. From an October sowing you should have buds showing colour six to eight weeks after planting, when the plants are about 75 to 100 cm above ground, and flowering typically starts in late May. After that you may still have to help the plants to hold on in the right places, but your main tasks will be to keep on cutting the flowers and keep the greenfly away.

Exhibiting. The art and delight of growing Spencer Sweet Pea flowers to perfection is beyond the scope of this advice, whether for competition or floristry. If you aspire to this art, you will do well to study The Complete Guide to Sweet Peas by Bernard R Jones, but there is no substitute for making the acquaintance of an expert in your locality as well. The book is available from Mr Mike Hargreaves, phone 044-(0)1943872069.