Sweet Pea Growing Instructions

A copy of these Growing Instructions is included with every order.

All the sweet pea seeds that we sell have been tested for germination at our premises near Maldon, Essex. Everything has a germination of at least 85%. For growing in countries other than the UK, please adapt these instructions for your local climate. In the UK Sweet Peas can be planted indoors from September and outside during March and April. For best results we recommend planting in the autumn (Sep-Nov) or winter (Jan-Feb) using the following method:


You will require a plastic box with a lid – a sandwich box, Tupperware or takeaway food tub will be suitable. Fold a double piece of kitchen towel to fit inside the plastic box. Add enough water to make the kitchen towel fully damp but without any standing water. Place the seeds on top of the damp paper, put the lid on and place the box in a warm place – a boiler or airing cupboard is ideal. Check the seeds after 2 days and you should see that they have swollen up. Within 4-7 days the seeds will produce the small shoots of the root and growing tip – at this point the seeds are ready to be planted into compost. If there are seeds that have not swollen, use a sharp knife or file to make a small hole in the seed coat and return the seed to the damp paper.

Preparing containers for sowing

We sow into sweet pea tubes or root-trainers for ease of handling and to avoid damage to the long roots when transplanting. Rolled-up newspaper or the cardboard tubes from toilet rolls or kitchen rolls will substitute. Alternatively you can sow into deep flowerpots or sow several seeds round the edge of a wider flowerpot. Fill with container with compost, gently firming to within 1cm of the top. Water the compost to fill this 1cm space, and then leave to drain. Using a cane or pencil make a hole about 1.5-2cm deep and put in the seed. If you are using the pre-germination method, it is best to use tweezers to prevent damage to the seed while transplanting. Cover the seeds with fine compost to fill the hole. The compost should be damp but not wet – our test is that if a few crumbs of soil stick to your fingers when pressed gently on the soil, it’s damp enough.

Early Growth

The first shoots should appear within 7-10 days depending on pre-germination and temperature. When the plants have 4 pairs of leaves, pinch out the growing point with the top set of leaves to encourage side shoots. These generally make a stronger stem that the original main shoot. Once seedlings have appeared, grow on “hard” with no heat. They need protection from mice and extra insulation if the weather is extremely cold.

Final Flowering Position

Plant out to final flowering positions as soon as weather and soil conditions are suitable - from early March in the south of Britain, to late March in the north. If you’ve used tubes, plant the whole tube to full depth. If you’ve grown in single pots, knock out the whole root ball, which should be held together by the root growth, and plant to a little more than full depth with a trowel. If you’ve multi-sown in larger sized pots, don’t leave them too long as the roots get inextricably tangled, knock out the pots, separate the roots gently to give single plants, and using a spade, dig a hole to the depth of the longest root, lay the root against the side of the hole, and using the back of the spade, firm soil up against the sweet pea root. Plant out at 30-45 cm spacing, and erect a frame behind the plants with wires or netting to allow the plants to twine naturally. Sweet peas grow remarkably quickly, and once into flower they use prodigious amounts of water, and, particularly in containers, will benefit from daily watering. Sweet peas use their tendrils to scramble up their surroundings but will eventually become sufficiently heavy that they fall over – at this stage they will begin to climb again. They can be tied up or tucked into the wires or netting. Maintaining the watering and picking the flowers regularly will promote longer flowering.

Lathyrus species

Other Lathyrus species are considerably slower to germinate so we recommend “nicking” or filing each seed a little to speed things up.

Additional Information: For further information about sweet peas, please visit the website of The National Sweet Pea Society www.sweetpeas.org.uk