Sweet peas (Lathyrus odorata) are annual climbing plants with fragrant and romantically ruffled, pea-shaped blooms. They were discovered in 1695 and have intoxicated gardeners ever since.
Lovely as they are, I had no burning desire to grow sweet peas until a recent visit to the Chelsea Flower Show. Inside the grand marquee were perfectly arranged waves of intensely fragrant sweet peas.
We planted Mr Fothergills ‘Hi Scent’, also sold as ‘High Scent’ and ‘April in Paris’ which has an exquisite form and
fragrance, as well as vase-friendly long stems. Bred by Dr Keith Hammett, this sweet pea is recognised as the benchmark
cultivar for scent and was given the Royal Horticultural Society Award for Garden Excellence. Our other favourite is the
maroon in the Yates ‘Colourcade’ mix. This year we are planting more of Keith Hammett’s sweet peas. Photo - Luisa
Suddenly I had to have them! It was if some ancient English genetic activity kicked into gear and I was helpless to resist its urges. I bought a few packets, argued with Australian customs and sowed them. That was the beginning of more failed attempts than I care to remember. Several seasons, and quite some research later, we have developed a successful strategy that sees the house filled with those lovely blooms all through spring. Here are our tips to help you do the same.
Sweet peas have intoxicated English cottage gardeners since their discovery in 1695. Photo - Linda Ross
The Chelsea flower shows stunners that hooked me were Spencer sweet peas. They were named by Silas Cole, head gardener to the Earl of Spencer, who in 1901 found a natural mutation in the garden under his care. The Spencer type became very popular because its ruffled standard (the upper petal) and long wing (lower petals) offered a bigger, more flamboyant bloom. There are many Spencer sweet peas and they remain very popular in England and Europe. But we had no success at all. Our weather just isn’t suitable. So we abandoned Spencers and switched to those developed by New Zealand’s eminent flower breeder, Dr. Keith Hammett. Hammett has developed cultivars that combine weather-tolerance and haunting perfume with larger size, a beautiful ruffled form and many rich colours and patterns. 'High Scent’ and 'Renaissance' are two of our favourites. ‘High Scent’, which is also sold as ‘Hi Scent’ and ‘April in Paris’ has an exquisite form and fragrance, as well as vase-friendly long stems. You can find it in the Mr Fothergills’ Collection. We also like Yates ‘Pink Diana’, the ‘Colourcade’ mix and ‘May Gibbs Sweet Pea Fairy’, which is a ground-covering, pink and white bicolour. Both thrive in our Sydney garden.
At the turn of the 19th century the introduction of 'Cupid', the first dwarf sweet pea, brought sweet peas into the realm of containers. This is the one to choose for hanging baskets, window boxes, pots, urns, and all other sorts of containers.
It was the display of Spencer sweet peas in the Grand Pavilion at the Chelsea Flower Show that ignited Linda's desire for sweet peas. Photo - Andrew Fletcher/Shutterstock.com
How to grow Sweet Peas
While sweet peas need plenty of sun, if you garden where spring weather can spring a scorcher (like the 35 degrees in September we experienced in Sydney last year!), sweet peas do better in a spot with morning sun and bright afternoon shade. Ours are in shade after 3pm. Choose a spot with good drainage.
Choose morning sun. Photo - Jeannette Katzir Photog/Shutterstock.com
St Patrick's Day is the traditional day for planting, but there’s no rush: sow seeds or plant seedlings in March, April or May. First dig deeply to loosen the soil and enrich it with a mix of mushroom compost and cow manure. Sprinkle a handful of lime per square metre over and leave for a fortnight before planting. Don't forget to set up a well-anchored trellis, fence or vertical support.
Here are a few of the more popular options for supporting sweet peas:
Tepee tunnel: Use bamboo for uprights and horizontals and add chicken wire or square mesh on the sides to maximise the hold.
Sweet peas growing on a narrow teepee tunnel. Photo - Luisa Brimble
Arched tunnel: Arch bamboo over and tie together at 50cm intervals. Use bamboo horizontals to firm up the structure. Make sure you can walk beneath the tunnel without hitting the arched roof! Add steel mesh for climbing support.
Vertical trellis: Tack chicken wire or mesh directly onto a fence; or onto inserted stakes.
Obelisk: Secure three or four bamboo of timber stakes in the ground and tie them at the top. ‘Pea sticks’ positioned around the obelisk will aid the tendrils of young seedling to grab hold.
These sweet peas are just beginning the climb up a timber obelisk. Photo - Jeanie333/Shutterstock.com
When sowing the seed, especially in light sandy soils, it helps to scarify it first. This means rubbing a spot on the seed opposite the testa - the little white bit where the roots emerge - on a piece of glass paper. Some gardeners like to soak sweet peas overnight before planting them; others never do it and still have good results. If you do soak seeds, be sure you leave them in water no longer than eight hours before planting immediately.
Sow two sweet pea seeds at the base of each stake. Water with half-strength seaweed solution with a pinch of Epsom salts added to the watering can. Do not water again until seeds germinate (and pray for dry weather!). Seeds that don’t germinate within two weeds have probably rotted. Sow some more, they’ll quickly catch up.
Photo - sarka/Shutterstock.com
Tips to success:
1.Sweet pea seedlings are very attractive to birds, slugs and snails, so protect them throughout the winter.
2.Avoid using too much fertiliser (particularly high-nitrogen feeds) or plants will produce lush green leaves but very few flowers.
3.Keep sweet pea vines mulched and well-watered for good flower production. Once they start to produce, be sure to pick stems every other day to prevent seedpods maturing. The more you pick, the more new flowers the plants will develop.
4.If you see signs of powdery mildew, spray immediately with Rose Gun, EcoRose or EcoFungicide.
5.Once the buds form, encourage flowering with a regular application of liquid flower fertiliser, such as Thrive Flower & Fruit, Harvest, Nutrafeed or Powerfeed.
6.Avoid over-watering and wetting the foliage. Instead water at the roots
Perfect posy. Pick flowers every second day to encourage more blooms. Photo - Luisa Brimble
Text: Linda Ross