Zanthan Gardens
Plant Highlights: Lathyrus odoratus

April 19th, 2007
Lathyrus odoratus

2004-04-23. Cupani sweet peas, larkspur, pink evening primrose, and love-in-the-mist make an old-fashioned bouquet.

Recently, Kathy Purdy at Cold Climate Gardening reviewed Graham Rice’s The Sweet Pea Book which told her everything anyone would want to know about sweet peas. I get the impression from her post and comments left by others that sweet peas are difficult to grow, especially in the US, especially in the hot dry south.

April, 1998. Bush-type ‘Explorer‘ sweet peas in a wild mix of ruby red, hot pink, and lavender climb over Texas bluebonnets and heirloom yellow irises.

I don’t remember what made me pick up my first packet of sweet peas. I never saw sweet peas growing or as cut flowers before I grew my own. Nor do I think I would have recognize the scent had I smelled some artificial form of it. (Although I’ve read it smells like the cologne “White Shoulders”, my mother’s scent, I don’t make that connection.) Being annual vines, they’re not something you see in the bedding out section of the big box stores. They are not easy to market to the masses these days as sweet peas are neither compact nor can be already flowering when you sell them. You can’t buy a flat of them to pop in for instant color.

Sweet peas were not only popular in another place than I garden but in another time. In Victorian times, British hybridizer Henry Eckford developed the Grandiflora strain, new colors with larger flowers and stronger stems. Then in the early 1900s, Silas Cole, the Spencer family gardener who had been making sweet pea crosses noticed one seedling with large frilly flowers. The Spencer sweet pea set off another hybridizing craze. By 1911 there were over 300 varieties of sweet pea. Only a handful of which survived to the 1980s.

Everyone I read from Celia Thaxter to Tasha Tudor to Steve Bender waxed poetic on lovely old-fashioned sweet peas. And the catalog descriptions from Select Seeds were enticing. I knew I had to try them.

I have always loved scented flowers best. Whether it’s roses, or herbs, or annuals, I’m drawn by the promise of scent. And both its English and botanical names conjure visions of a garden where sweet odors waft in summer breezes. (Visions of a summer obviously not in Texas. How difficult it is to garden where you are when you’re reading sumptious descriptions in garden catalogs.)

They are incredibly easy to sprout from seed…if you start them in the right season. In Austin that’s fall. The first few times I tried to grow sweet peas, I followed the instructions to plant them early in spring as the ground could be worked. That’s too late. Sweet peas seem very unhappy whenever the temperatures hit the 80s…and we can have days in the 80s even in January.

In A Woman’s Hardy Garden, Helena Rutherfurd Ely devotes two lengthy paragraphs to sweet pea culture, including (as Annie mentioned) digging a trench a foot wide and a foot deep, putting a manure at the bottom of the trench, and filling it partially with rich earth and wood ashes. The idea is to hill them up as they grow, so that the roots will remain moist and cool.

Celia Thaxter gives almost the same prescription in An Island Garden

I find Sweet Peas can hardly have too rich a soil, provided always that they are kept sufficiently wet. They must have moisture, their roots must be kept cool and damp,–a mulch of leaves or straw is a very good thing to keep the roots from drying,–and they must always be planted as deep as possible. Wood ashes give them a stronger growth.

Given these demands, I’m surprised I’ve ever managed to grow a sweet pea at all. Generally, it’s too hot, too dry, and Austin’s soil too thin and shallow. Our one advantage in Austin is that we’re over limestone. Sweet peas prefer limey soils (thus the love of wood ashes).

Once you manage to get them flowering, you have to deadhead spent flowers vigorously or they will give up and go to seed. This isn’t hard if you have time to cut bouquets each morning. And that’s one of the pleasures of growing sweet peas.

Heirloom sweet pea ‘Cupani’ is scented and less bothered by the heat than some newer varieties.

I’ve had the most success with ‘Cupani’ an old sweet pea that people have been growing since the late 1600s. Unlike newer varieties that were bred for showy flowers rather than scent, ‘Cupani’ remains sweetly scented. It also blooms longer and has even self-sown in my garden.

In 2001, I planted ‘April in Paris‘ and the Spencer type ‘North Shore’ in September but had very poor luck with them.

This year I started ‘Velvet Elegance’ on November 24th, planting them into the vegetable garden. They are supposed to be day-length neutral so they start blooming earlier than standard sweet peas. Most were up by December 15th and I transplanted them. They began flowering on March 10th and are still flowering but I didn’t keep them moist enough during some of our 80 degree days and about a third of them have died. Some of the flowers are a beautiful lavender/periwinkle (the seed-packet says “deep violet-blue”). Others are a maroon that I’m less fond of.

‘Regal Robe’ produced a mix of colors, some dark burgundy, others rich cream.

I also started ‘Regal Robe’ on December 22nd, transplanted them on January 12th and 31st. They began flowering on March 25th. So far I like ‘Regal Robe’ better than ‘Velvet Elegance’ because the flowers are larger, more frilly, and have more scent.

Overall, my success with sweet peas has been marginal. Mine don’t look anything like the show flowers I see in garden magazines. I manage to get a few flowers in April and May each year. Perhaps one of these years I will get serious and dig a trench. Maybe put up a sturdy trellis. After all, there are so many varieties to try with new ones coming along every year. I think I’ll always leave some space somewhere to grow sweet peas.

by M Sinclair Stevens