The past few years has seen an explosion of popularity for sweet peas in the US, but for those of us living in the central and southern parts of the country, getting them to grow well can be a challenge. We've compiled our years of growing in the Southern Plains to help you get started, and we'll start with some basic questions and answers.
Do you need to soak your seeds before planting?
The short answer is no. Seeds will germinate in 7-14 days with about 90%+ germination rates without soaking. We find it to be an unnecessary step, and there are professional growers that suggest soaking your sweet pea seeds can introduce pathogens and even reduce germination rates for those varieties with softer seed coats.
Should I fall plant or spring plant?
What type of Sweet Pea should I plant?
When most people think of sweet peas they're usually thinking of the Spencer type, but there are several types available. Spencers are known for their very frilly and full petals and wide range of color choices. Grandiflora, also sometimes known as Old-Fashioned, have smaller flowers and shorter stems but make up for it with amazing fragrance. Early-Flowering types are varieties that will start blooming at 10 to 11 hours of daylight.
If started early enough, and if the year provides a cool spring, Spencer varieties will do well. If you'd rather have more assurance of a good sweet pea bounty, then you should consider growing the Early-Flowering types. These include the Mammoth Series, the Winter Elegance Series and the Spring/Winter Sunshine Series. Although the colors available are somewhat limited, you'll find all the core colors.
General Notes and Methods:
When planting, remember that Sweet peas like consistent moisture and fertile soil. Ph should be around 6.0 to 6.5. Preparing your flower bed or rows with compost and amendments (like sulphur or lime) the season before you plant makes the process easier.
We plant our sweet peas in 2' wide rows with a 2' wide path in-between. Our alignment is N-S because our prevailing wind is from the SE and it also allows for a most even distribution of sunlight to the plants. We plant our seedlings at 6" apart (sometimes closer), but the risk for foliage disease increases with a lack of airflow. Other growers use an 8" spacing to help combat this potential.
After planting in their final location, you don't need to put up support right away. If you live in an area that occasionally gets a late deep freeze, you don't want to have to fight a trellis while trying to cover your small plants with frost cloth. Plants often seem to 'sit' for about a month in the ground without showing growth. This is because things are happening underground as the root structure grows. After about a month, you'll start to see substantial growth in the leaves and stems. It's right at this point we put up the support system. This also generally coincides with no more freezing weather.
You don't need fancy or expensive containers to successfully grow sweet peas. Some people promote the use of Rootrainers, and while these do work very well, they aren't necessary. We start all our plants indoors using a 50 cell tray. We've used both the 50 Deep and the regular 50 and our personal preference is to use the regular 50.
Sweet Peas have a short vase life with most varieties last about 4-5 days. Whether you choose to enjoy them on the vine or take them into the house, you'll want to keep up with cutting so that they won't go to seed and end the season early.