By far the most breeding has been done with the famed Spencer sweet peas. The very first of its type was ‘Countess Spencer’ a variety introduced in 1901. Spencers have large ruffled flowers and have been bred in a wide range of colors and patterns for more than a century. In his book, Roger Parsons tells us that as of the 1980’s all available Spencers were solid colored, meaning that the bicolors, and striped and flake patterns have all quite recently been bred into Spencer form. Spencers are the sweet pea of choice for exhibitors in the UK, where the standard requires 4 flowers per stem- no more and no fewer. Spencers are also considered “Summer Flowering” in that they need 12 or more hours of sunlight per day to come into flower. They are no more or less heat tolerant than their counterparts despite being summer flowering. While they have the widest range of colors and patterns, Spencers may be a poor choice for growers in warmer areas as temperatures become too hot before the required 12 hours of day length has been achieved. The majority of the varieties we grow and sell as cuts, plants and seeds are Spencers.
You would be forgiven for expecting grandifloras to have large flowers. They were so named prior to the discovery of Spencers in 1901, so for a time, they were in fact the largest flowers in the species at the time. They have “plain” standard petals rather than the ruffles seen on Spencers. In general they have shorter stems and smaller flowers as well. Why on earth would you grow such a thing with small plain flowers? Their streamlined shape makes them more rainproof in the garden, and in general they are amongst the most fragrant sweet peas. When I grow sweet peas meant to be cut “on the vine” I prefer grandifloras. Their shorter racemes are more in scale with the leaves and stem supporting them than are Spencers when cut with stem attached. They are prolific and free flowering, and are perfect for growing outdoors and for general garden enjoyment. Grandifloras are still being bred and you sometimes see newer varieties dubbed “Modern Grandifloras” especially if they display novel characteristics. Even though the term grandiflora wasn’t used until the late 1800’s, flowers with this shape have been cultivated for more than 300 years with good reason. Don’t overlook the grandifloras.
Some varieties are not quite as ruffled as Spencers and not quite as plain as grandifloras, so we split the difference by calling them semi grandiflora. They are larger than grandifloras- big enough to raise for cutting. They have slightly wavy petals and some of the most intense fragrance of all.
Early flowering types are sometimes called “winter flowering” or “spring flowering” as well. These types flower with as few as 10 or 11 hours of day length respectively. While you could theoretically breed an Early Spencer or and Early Grandiflora, most of the work in early flowering sweet peas has been by cut flower producers who want more flowers per stem. Why do they want them to start flowering early? Because by and large they are growing them in heated greenhouses in the winter months, and can’t wait around until summer for their plants to start blooming. As they were produced by cut flower specialists these types tend to have 5 or 6 flowers and often longer stems than Spencers. These are the types I most recommend for Southern growers or locations with hot springs as they will often start before flowering before the true heat of summer sets in. These types are most often sold as part of a series. Winter Sunshine, Spring Sunshine, Winter Elegance, Mammoth, and Solstice to name a few. The “winter” and “spring” terminology has nothing to do with cold hardiness, it simply means they will start flowering earlier than Spencers. Many of the Early Multifloras have Spencer type ruffled flowers, but you commonly see some that have reverted to Semi Grandiflora in their flower shape. In general if a Southern grower gets a good harvest of long flowered sweet peas, they aren’t counting the ruffles on the petals, they are rejoicing in their success! Early sweet peas can just as easily be grown in the summer months in cool northern locations despite being well suited to the South.