Sweet peas are old fashioned annuals with ruffly, fragrant flowers in shades of blues, purples, reds, pinks, and whites. They’re essential in flower and cottage gardens and for the best show of flowers, you’ll want to start the seeds at the right time. This article provides all the information you need to know about starting sweet peas seeds indoors as well as direct sowing in the garden. If you’re wondering when to plant sweet peas, keep reading.

Sweet peas (Lathyrus odoratus) are one of the most popular types of flowers and grown for their colorful and often scented blooms. Most sweet peas are vining annual plants that grow 6 to 8 feet tall and need the support of a trellis or other structure. That said, there are also compact sweet peas, like the dwarf variety ‘Knee Hi’, that have bushy growth. These are perfect for pots and baskets. Antique varieties produce 3 to 5 pea-like flowers per stem, while choice varieties like ‘Spencer’, ‘Cutherberson’, and ‘Mammoth’ have been bred for long stems and extra-large blooms, with 5 to 6 flowers per stem.
Knowing when to plant sweet peas is the best way to encourage the most productive plants. They’re side of cool weather and unbothered by light frost.
– Autumn: In zones 8 and above, sweet pea seeds should be planted outdoors in autumn. They’re typically sown, about the same time spring-flowering bulbs are planted. You may not see a lot of plant growth in autumn, but the seeds are busy developing robust root systems and quickly sprout up when the weather warms in spring. Some gardeners in mild regions plant a second sowing in early spring to ensure the longest season of sweet pea flowers.
– Early spring: In sweet peas are planted late winter through early spring. Seeds can be sown directly in the garden or started indoors. I start my sweet pea seeds indoors as transplanting seedlings results in more vigorous plants than those that are direct sown. Below you’ll learn more about when and how to start sweet peas seeds indoors as well as get tips on direct sowing in garden beds

now I know when to transplant the seedlings in my garden, but when do the seeds need to be started inside? Next, we need to look at how many weeks of growth sweet peas need indoors before they’ve moved outside. They’re fairly quick to grow and should be sown indoors 4 to 6 weeks before you intend to transplant them to the garden. This means I need to count backwards 4 to 6 weeks determinate the indoor planting date. A quick glance at the calendar tells me I need to start my sweet pea seeds under my grow lights sometime.