episode 49 | show notes & advice
Spectacular sweet peas are the subject of today’s podcast. Sarah and Arthur love them and if they were sent to a desert island, they would both definitely take a pack of sweet pea seeds with them to grow.
Sweet peas are the emblem of the cut flower movement, as soon as you cut a bunch you’ve got another almost ready to cut again off a wigwam, arch or frame in the garden. In this episode, Sarah and Arthur share their tips and advice to help you grow strong, healthy plants for bucketsful of sweet peas.
In this episode discover
- Why sowing sweet peas in Rootrainers is better than loo rolls or pots.
- What to feed sweet peas for healthy, mildew-free plants.
- How to make your own wigwam for sweet peas to gallop up.
- The varieties Sarah and Arthur are growing this year.
- Sarah’s technique for a quick and easy sweet pea table centre.
For Sarah, sweet peas feel like a celebration of the British countryside and the country garden. They are so generous and scented, the more you pick the more they flower - the epitome of cut-and-come-again flowers.
Arthur thinks of Sarah as the Queen of sweet peas more than dahlias or tulips. The first time he saw her was on Gardener’s World with Monty Don, using Rootrainers to sow sweet peas.
Why you should use Rootrainers with sweet peas
Rootrainers take advantage of the physiology of the legume family. These plants love a long, thin root run. They put out a tap root when they germinate that goes down deep until it hits a barrier (or just comes out into the air) and then breaks. Lateral rootlets then form along the length of the tap root. Sweet peas and other legumes are often sown and planted out in cardboard loo rolls to take advantage of this. Rootrainers are better because they have channels down the sides as well as being long and thin like loo rolls. In a pot or loo roll, when the lateral roots reach the side, it takes them a while to travel down to reach the bottom. With a Rootrainer, the rootlets go into these side channels and very quickly get to the bottom where they are air pruned, breaking off naturally.
Trials at Perch Hill measured the speed of sweet pea growth in different containers, a 9cm pot, a loo roll and a Rootrainer. Sown in a loo roll, they grew twice as fast as in the pot, and in the Rootrainer, a plant-out-able seed was ready at three times the speed.
Now is the perfect time to sow sweet peas
Early in the New Year, a mass sowing of sweet peas is one of the first things that gets done at Perch Hill. Sweet peas are hardy annuals that are happy planted out from the middle of March in Sussex. They thrive, as do broad beans, in cold weather with lots of rain and this time helps them put deeper roots down before the strain of flowering. They sit happily in the garden from March into May then suddenly shoot off and climb up frames. By the end of May, if you have sown seeds in January or February, you should have flowers.
Arthur’s favourite varieties
Arthur loves tall-stemmed varieties for picking sweet peas. The biggest come from the Spencer group, as in Lady Diana Spencer – Princess Di. Her family gardener bred sweet peas, creating big and blowsy varieties with gorgeous flowers. They can lack huge perfume so Arthur’s tip is to mix and match one Spencer sweet pea with an older, more scented variety. Newer sweet peas have more common names like Arthur’s favourite ‘Barry Dare’. The older varieties tend to be named after Lords and Monarchs. Arthur will plant Barry with ‘Prince Edward of York’.
Sarah agrees with this mix and match approach and she loves ‘Lord Nelson’, a famous old variety that gives you knockout scent, or ‘Black Knight’, which she will pair with one of the new modern grandiflora Spencers like ‘Almost Black’ for tall stems and sumptuous flowers.
Top tips for growing sweet peas
· Think about sweet peas in autumn/winter
Arthur grows sweet peas in pots and starts thinking about them when planting bulbs in autumn. When tulips are at their peak, that is the best time to plant out sweet peas and, if all his pots are full of tulips, he will struggle for space. He prepares some big, deep pots with birch wigwams and early spring bulbs like crocus so he still gets a nice flurry of colour in February and March. In April he lifts the crocus and enriches the soil, packing in molehill soil and chicken manure/organic homemade compost, great for hungry sweet peas.
- Feeding sweet peas is crucial
Feed and water sweet peas once a week – if they go hungry, they don’t flower and get mildew. They love liquid seaweed or a potash-rich feed made from comfrey pellets. Or you can also chop up comfrey leaves – get an empty cider barrel or wine box with a tap, pack in comfrey leaves, fill with water and leave for two weeks. Then put the stinky liquid into old milk cartons, keep in the shed, then dilute 1/10th in rainwater ideally, when ready to use. Potted sweet peas particularly benefit from this tonic and it keeps mildew at bay.
· Use the cold to stop sweet peas getting leggy
If, like Arthur, you germinate sweet peas inside on windowsills, he recommends when your seedlings are 3 inches (8cm) high put them outside into a cold frame – the cold stops them getting elongated and leggy. They need protection from wind and rain so a cold frame is ideal. They won’t put on top growth and this will encourage strong root growth and formation.
· Remember to pinch out
Once there are four pairs of leaves on the seedling, pinch out the tip to create a strong, bushy plant with lots of flowers.
· Cordon growing sweet peas
Cordon growing is a method that forms bigger flower stems with more flowers. Allow one vine to grow up the cane, pinch out all the side shoots, just like you do with tomatoes. When it gets to the top of the cane, take it two or three canes along and turn the tip up that – this will give you a second crop.
This method works but it is a palaver and Sarah and Arthur don’t do it anymore – they just let sweet peas romp up a silver birch teepee or a hazel and jute frame.
- Pick the right structure for sweet peas to grow against
There are suppliers online who can provide bundles of birch which you can use throughout the growing season to make wigwams or nest supports for dahlias.
Expensive garden centre teepees are too small so it is worth making your own tall ones for your sweet peas to gallop up – 7ft (2m) high is ideal.
How to make your own teepee
Put a pot or dustbin lid on the floor and arrange an odd number of canes - 5 or 7 - around this circle. Bunch the canes at the top, you will need a chair to do this, and tie together using something like flexi-tie. Arthur finds string is too loose - flexi-tie is better and can be reused.
If you have only got bamboo, make your teepee then tie hessian garden string to the base and create a cobweb effect up and around the teepee so that sweet pea tendrils have something to latch on to. Bamboo is too slippery on its own - sweet peas need a tactile grip to grow up.
· Pick flowers and tendrils
Once your sweet peas are flowering, pick big tendrils that haven’t latched on as well as flowers – this will encourage more flower production.
Sarah’s top tip for sweet pea picking
Sarah uses this technique to pick sweet peas. She puts rubber bands on her wrist and takes a bucket of water to put her sweet peas in and a tubtrug for deadheading. Using florist scissors she picks one variety in a bundle, uses a rubber band to secure, then plops into the bucket of water. She then moves on to the next colour and repeats. Inside, she places each bunch in a vase – she tends to use a glass hellebore bowl for sweet peas - cuts the rubber bands and schuzhes a bit to arrange.
This is a quick and easy way to make a lovely table centre.
Chelsea chop your sweet peas for longer flowering
To get sweet peas flowering for longer, you can do a kind of Chelsea chop. Once sweet peas are flowering away in June, Sarah will pick up to 75cm (30in) into the plant, which might have five flowering stems on that section. This gives lovely curtains of sweet peas in the vase. The plants will then push out axillary buds at that lower level and will produce flowers again about three weeks later. This means you don’t need to deadhead and it is a good idea to do this before going on holiday. At Perch Hill, this is the picking system used for varieties like ‘Matucana’ which is hugely scented but has short stems.
Sweet pea origins
Sweet peas come from the South of Italy originally. You find them growing in the wild in Sicily. An Italian monk called Cupani bred from these wild sweet peas, selecting for long stems and more flowers. He sent seeds to the Chelsea Physic Garden and to a village in the Andes called Matucama, this is how sweet pea breeding began and is why ‘Cupani’ and ‘Matucama’ have their names.
Read the sweet pea story - Sarah Raven for more on the history of sweet peas.
Sweet pea varieties Sarah’s growing this year
Sarah separates sweet peas into colour palettes – dark and rich sweet peas mixed with brights to bring zest and fruitiness - she will match ‘Winston Churchill’ and ‘Windsor’ with ‘Lord Nelson’, ‘Blue Velvet’ and ‘Matucama’.
She will do another colour palette including some speckled pale sweet peas - early-flowering ‘Nimbus’, beautiful pale flowers with dark rich purple wings, along with ‘Lilac Ripple,’ another beauty, or ‘Wiltshire Ripple’.
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