Growing sweet peas can be a challenge, especially here in Maine. But determination is what keeps us gardeners going, right? Gardening demands patience: it's effort and experience combined to achieve great satisfaction.
That tiny seed develops roots, leaves and a flower that delights! Sweet peas have an added benefit; FRAGRANCE! The flower is a lovely lace-like folded grouping of petals. Available in a wide range of colors. My favorite variety is 'Henry Eckford' an orange sweet pea. Available from Baker Creek Heirloom Seeds.
I've had successful germination using a long plastic rooting pot called a root trainer. It's available from Sarah Raven. This long pot allows the roots to grow quickly spreading into the well designed side channels of this container thus increasing lateral bud development. The root trainer is hinged to allow for plant removal with out damage to the roots. Sweet peas don't like to have their roots disturbed.
Place the growing mix with some time released fertilizer in the cells and plant two seeds per cell at a depth of 1". Backfill with growing mix and water well. Use a fine spray when watering. Tip: I sometimes invert or turn my sprinkler head of my watering can upside down to create a fine more mist like flow. When leaves have emerged and are about 2" tall and roots are visible from the bottom of the root trainer the plants are ready to pot. Place the two plants in a tall pot and place in the cold frame. The plants should be ready for direct planting in mid to late April (here in Maine ~ I'm zone 5).
A trellis type support will be required for the sweet peas. When the plants are about 6" to 8" high, pinch and mulch well. Water regularly and you should have a successful bounty of sweet peas. I've made a support using foraged small 2" diameter tree branches, about 6' in length, with inexpensive chicken wire stapled to the branch poles. It works great and I love the rustic look in the garden. Good luck planting. Please contact me with any questions or share your stories, I'd love to hear how you've made out?