Sweet peas or 'Lathyrus odoratus' to use it's latin name are possibly my favourite cut flower; I think homegrown English roses give them a run for their money but other than that I can't think of a plant that is so simple to cultivate annually, that gives such a delightful display of colour and scent and is a perfect cut flower.
If you enjoyed the rainbow bright, pastel and sorbet shades floating down the Chanel catwalk last autumn for the SS14 shows sweet peas may be the flower for you. Think about these beautiful clothes for a moment, now imagine they are scratch n sniff with the most delicious scent imaginable and you will have an idea of what it's like to walk past sweet peas in full-bloom on a warm summer day.
If this is something you would like to experience now is the time to take action. Sweet peas are from the same family of plants as regular peas (don't eat the seeds though, they are toxic when ingested in quantity) and they have similar requirements. They fix nitrogen into the soil, which is a great thing for companion planting as it helps to enrich and fertilise the soil, although I would point out that this occurs from nodules on the roots of the plant after it dies.
Sweet peas have long fibrous roots so they should be sown in deeper pots (9cm are perfect) than most other flower seeds. Garden centers sell root trainer pots or sowing trays for this purpose but you can achieve the same results using the cardboard inside of a loo paper roll. Not only is this method cost effective it also has the advantage that the germinated seedling can be planted out without disturbing the delicate roots.
Image borrowed from Crocus.co.uk
A lot of gardeners swear that keeping the seeds in the fridge for a few weeks then soaking them overnight prior to sowing will help improve germination rates. I've never done this and in my experience as long as the seeds are fresh and well watered after sowing the germination rate remains excellent.
Here are some simple steps to follow:
1) Prepare a deep seed tray with well drained seedling compost (do not use soil from the garden, it's not sterile).
2) With a dibber, or the end of a pencil make a hole about 1cm deep in each pot or module in the seed tray.
3) Sow one seed in each hole.
4) Cover the seeds with compost.
5) Water the seeds in well, allow to drain and place a polythene bag over the tray (this regulates moisture levels).
6) Keep at a temperature of about 15ºC (59ºF) until germination occurs, then remove the polythene bag.
7) When the seedlings have two true leaves move them to a well ventilated coldframe making sure to protect them from heavy frosts.
8) Plant out the seedlings in good well drained garden soil in April after the last frost.
9) Pinch out the growing tip once the plants reach 10cm high, this encourages bushy growth and more flowers.
10) Protect the young plants from slugs and support with pea sticks or similar as they grow.
11) Pick the flowers regularly to encourage new blooms. Deadhead any spent flowers.
Sweet peas give a lot as a plant so they need regular feeding and watering to maximise cropping potential. Spray for any pests, such as aphids and diseases such as powdery mildew. You can purchase good quality sweet pea seeds from any reputable garden center, the only decision you may struggle with is which colour(s) to choose.