A packet of sweet pea seeds in a nice greeting card makes a great Christmas present. The main reason being is because that these seeds can then be sown by the recipient on Boxing Day! Sweet peas are vibrant and full of scent. A bunch of them is a beautiful thing to behold to the senses, but they are one of the most demanding cut flowers to grow – so if you’re going to try growing them, it’s good to know the easiest ways of how to get the very best from them.
I've just sown next year’s sweet peas for the factory garden in the greenhouse here. Three seeds go into a deep rather than square pot – the sort that you buy rose plants in that holds two litres of soil. This is because sweet peas like a long root run from the start of their germination. Traditionally, sweet peas are sown into cardboard tubes. The cardboard however, once wet, often becomes mouldy and rots away within a few weeks so I find that plastic works better. Each seed goes into the pot at about an inch deep, to the first knuckle on your finger.
You can also use root trainers that copy the idea of a bunch of cardboard tubes. Whatever you choose, it’s good to sow these hardy, climbing annuals now, ideally before March so that they can form strong root structures.
If you don't have a greenhouse, plant the seeds on a cool windowsill. I don’t soak the seeds in water beforehand. Without being soaked overnight (which does speed up germination) they will normally take a good two weeks to germinate. If you have a greenhouse, then it’s vital to make sure that it is free from mice, as they will treat the seeds like their Christmas Ferrero Rochers!
Once the seedlings are an inch tall, move them to somewhere sheltered, frost free but cold and light, such as a porch or a slug-proof glass garden cloche. With all seeds, and especially sweet peas, you want bulky, chubby little plants not long, thin whips.
When the little seedlings have four pairs of leaves each, pinch their tips out. This well-known treatment will encourage the plants to form side shoots, resulting in more flowers.
A mature root system will help the young seedlings to get going with gusto when they are planted out in the garden. This happens normally here in late April. Strong sweet peas are less likely to succumb to mildew. They will happily climb up twiggy silver birch and hazel stems; otherwise, you can use canes wrapped strung through tightly with brown twine.
They are hungry plants, so feed them from the outset of planting them in their final positions with well-rotted chicken manure, dug well into the soil before planting them out. If you don't have this, then organic chicken manure pellets are a good alternative. Once they are flowering, you must pick them and continue to do so as much as you can. The tendrils are best removed weekly as blooming starts. This is a long job, but if left, the tendrils will take a lot of the plants’ energy and will trap emerging flowers. Regular watering in the summer is also vital.
Winter sown sweet peas will out do spring sown plants by miles. Once you’ve sown them in the winter and seen or rather picked the difference, you’ll never sow them in the spring again!
The sweet pea tunnel in the garden this year was a huge success and was well worth all the above mentioned efforts. I'm repeating it next year but using other climbing annuals more, such as black eyed Susan's to ensure that the tunnel looks colourful deep into late summer. When the sweet peas eventually go to seed and become brown, these later flowering annual climbers, will keep the vertical display looking vibrant into October.
Arthur's favourite sweet peas all have a good stem length and a good, strong scent - 'Lord Nelson' 'Barry Dare' 'Almost Black' - available from sarahraven.com.