I plant my sweet peas indoors in early April in cell packs that have fairly large cells.
For a lot of years I would be a very frustrated gardener in late August and early September when the first fall frost ended the display of sweet peas in my garden. It seemed that every year the sweet peas were just nicely coming into their full glory, they would be cut down by frost. I determined to solve this problem.
The solution came down to how the growing season for my sweet peas could be lengthened. Extending the bloom time in the fall by covering the plants to protect them from frost was almost impossible because by fall the plants are so large and the weight of any cover would break them down. It seemed easier to try to extend the growing season in the spring by starting the plants earlier.
I tried to seed my sweet peas outdoors earlier in the spring, but the soil was still very cold so germination was either slow or many of the seeds rotted before they germinated. Then I tried an experiment – planting sweet peas indoors like other bedding plants and giving the plants a good head start before transplanting them outdoors along the sweet pea fence. The plan worked.
Now my sweet peas begin to bloom by the end of June, and by early September they have pretty much bloomed themselves out. By then I have enjoyed over two months of bloom from the plants and I am more willing to allow them to be claimed by Jack Frost.
I plant my sweet peas indoors in early April in cell packs that have fairly large cells (6×6 centimetres). I germinate the seeds under the lights of my light garden and leave the seedlings in the light garden until they become about 15 centimetres tall. Then I move them to an outdoor cold frame (which has a heater in it for cold nights) where the plants are exposed to full sun. The seedlings in the cold frame grow into sturdy, hardy plants. If I think they are getting too leggy, I pinch off the top of each seedling which encourages the plants to branch out from each leaf node. If you don’t have a cold frame, grow the plants on a sunny windowsill and place them outdoors during warm days.
As soon as the soil has warmed up sufficiently and danger of hard frost has passed, I transplant the sweet pea seedlings into the garden. I may have to protect them if a late frost is forecast, although they are somewhat frost tolerant once they get established. The roots are disturbed very little as a result of my having used cell packs, and they suffer little if any transplant shock. Of course they are already perfectly hardened off because of their exposure to the elements in the cold frame.
If you are tired of waiting until late summer to enjoy the blooms from your sweet peas, consider giving them a head start by planting the seeds indoors in early April. You will have many more weeks of being able to pick those wonderfully fragrant sweet pea bouquets from your garden.
– Albert Parsons writes from Minnedosa, Manitoba