Sweet Pea Seeds in Ireland

There are two windows and both work. October is the better one: sow into deep pots or root trainers, germinate them in an unheated greenhouse or on a cool windowsill, then overwinter the young plants in a cold frame or unheated greenhouse. They sit through the winter building a substantial root system and go out in March as sturdy plants that flower two to three weeks earlier and for longer. The second window is February into March under cover, which is easier because there is no winter to nurse them through, and still gives an excellent display. Direct sowing outdoors in April works in a mild sheltered garden but produces later, smaller plants.

Usually neither. Modern seed is generally sown straight into moist compost and germinates in ten to twenty one days. Soaking overnight is traditional but it is also the fastest way to rot a batch, because a swollen seed in cold compost in an Irish February is sitting in ideal rotting conditions. If you have dark or heavily mottled seed, which tends to have the hardest coat, chip it: take a sharp knife or a piece of sandpaper and just break the surface on the opposite side from the eye, then sow immediately.

Sweet peas are legumes and they send down a long tap root very early, well before there is much on top. In a shallow module that root hits the bottom, spirals, and the plant is checked before it starts. Root trainers, deep cell trays, 9cm pots filled to the top or homemade tubes of newspaper all give the depth needed. It is the single cheapest improvement most people can make to their sweet peas, and it matters far more for an October sowing that will sit in its pot for four or five months.

Yes, and it feels wrong the first time. When the seedling has three or four pairs of leaves, pinch out the growing tip just above a leaf joint. The plant responds by producing several strong side shoots from the base instead of one thin climbing stem, which means far more flowers. Autumn sown plants can be pinched in late winter before they go out. Skip this step and you get a tall, spindly plant that flowers thinly at head height.

Not all of them, which surprises people. Breeding for larger, more ruffled flowers and longer stems through the twentieth century cost a lot of scent, so many modern Spencer varieties have flowers three times the size of the original and very little smell. The old fashioned or grandiflora types, with smaller flowers and often bicoloured, are where the strong scent lives. Cupani and Matucana are the reference points. If scent is the reason you are growing them, read the packet carefully and buy an old fashioned type or a Spencer specifically described as scented.

You stopped picking, or you missed some seed pods. An annual plant flowers to set seed, and as soon as pods start to form the plant shuts down flower production. Picking every two or three days, and removing any pod you find, keeps a sweet pea flowering into September in Ireland. The other cause is dry roots in a hot spell, which brings on mildew and finishes the plant early. Sweet peas need far more water than people give them.

The seeds and pods are not edible peas, despite looking exactly like them, and no part of a sweet pea should be eaten. Be clear about the actual risk though, because it is often described loosely. The documented harm is not sudden poisoning from one pod; it is lathyrism, a condition affecting bone and nerve tissue that follows eating quantities of the seed steadily over weeks or months, and it is documented in people as well as livestock. So a child who bites one pod is not a poisoning emergency, while a child who has decided the wigwam is a snack bar is a problem worth interrupting. Grow them at child height by all means, but say plainly that these particular peas are not for eating. The flowers are also not a food garnish, unlike edible pea flowers.