Sweet Peas (aka Queen of the Annuals)

Welcome to the Member Ideas area! This community feature is where our members can post their own ideas. These posts are unedited and not necessarily endorsed by the National Gardening Association.
Posted by @Joannabanana on
Lathyrus odoratus, the annual sweet pea, intrigues gardeners everywhere and the quest for an enchanting display of fragrant walls of colour is one of the most desired displays for many gardeners. Your geographical location will dictate whether sweet peas will be a winter, early spring or late summer and fall bloomer for you. There are a few things to do and consider in preparation for beautiful sweet peas in your garden.

Sweet Peas originate from the Mediterranean and are naturally an early spring bloomer. Blooming period is extended with cooler temperatures, but once the heat of summer sets in, sweet peas are at the end of their natural life cycle. The life cycle is complete in one year. Seeds germinate in late fall or early winter with slow top growth for a few months. It may seem that they have stalled, but there is lots happening under ground. They need this long cool growing period to develop a strong root system. As spring approaches, the days become longer, a trigger for top growth. The sweet peas start a rapid growth period and flower buds form with 12 to 15 hours of daylight. Late spring/early summer heat initiates pod formation and as the days get hotter, the pods ripen and the plant dies. The tough seed coat is key for the seed to stay dormant until the conditions are favorable for the cycle to start again in the fall.

Many different growth habits are available from 10” dwarf mounding varieties to vigorous 8’ tall vines. Vines will require support with netting or stakes for the tendrils to attach to, including the 2’ to 3’ vine varieties. Dwarf varieties are well suited for containers or border planting. Inter-planting short and tall vines produce a wonderful wall of colour from bottom to top.

There is a wide range of colours offered in today’s market. Blue, pink, purple, red, white, and even orange are available in either mixes or individually. No yellow though. Bi-colours with unique patterns also offer a beautiful option for streaks, stripes, flecked and edged flowers.  The Spencer varieties have large ruffled flowers. Some varieties have up top 5 flowers per stem.

Thumb of 2012-12-31/Joannabanana/511272

Most varieties are fragrant, but do check the seed package description. Often the larger flower varieties have a mild fragrance. If there is no mention of fragrance, chances are they may have little to none. Many of the most fragrant varieties have small flowers. Look for scent or fragrance descriptions within the variety name or on the seed package. Typically the white and pink colors are the most fragrant in mixes. Heirloom or Heritage varieties are often highly fragrant. One of the oldest varieties that is still available is “Painted Lady” cultivated since the 1700’s. I planted Mammoth which was a bit disappointing since the scent was very light. The flowers were early and pretty though.

Sweet Peas prefer cool temperatures for both germination and seasonal growth. There are numerous varieties with different growth habits that are bred for heat tolerance. In hot conditions, choose a planting area that has afternoon shade. East exposure may be an excellent option providing early morning sun and shade during the hottest part of the day. Heat tolerant varieties like Villa Roma Scarlet (fragrant dwarf) are great choice for hot conditions.

Choosing the most appropriate bloom season will be the success for your sweet peas. Most sweet peas require more than 12 hours of daylight, but there are now some new varieties that are semi daylight neutral, which will produce flowers with shorter day lengths. Here are some examples:
Very Early (daylight neutral): Winter Sunshine, Elegance, Lunar and Equinox.
Early (semi-daylight neutral): Mammoth, Streamers and Royals, a bit later
Later (daylight sensitive): Spencers and Cuthbertosons.

Spring, Summer, or Fall Blooms for Your Garden

If your ground doesn’t freeze during winter, direct sow in October for blooms in late winter to early spring. This is about the same time you would plant your fall bulbs. They will germinate within a few weeks and have slow growth for a few months. If your area skips spring (gets early season hot temperatures) you may want to start them indoors to speed up germination and transplant out. In both situations, choose varieties that are not daylight sensitive, since the days will be less than 12 hours daylight at that time of year. Look for variety descriptions to include: Short Day Flowering, Very Early to Flower or Winter Sweet Peas.

If you have mild winter conditions and an early spring, direct sow two crops. Sow one crop in the fall and the second crop as soon as the ground can be worked in the spring (6 to 8 weeks before average last frost). Winter sowing technique in milk jugs would be a great option as well. Remember, the plants will have slow top growth for the first 6 weeks, which is normal. Expect blooms about 12 to 14 weeks after germination with over 12 hours daylight.

For the folks with severe winter conditions and cool summers, starting the seeds indoors with cool growing conditions 6 -8 weeks before last frost will give you early summer blooms. Direct sowing as soon as the ground can be worked will produce August blooms. Winter sowing techniques will give you about a month earlier bloom than direct sowing. Planting a combination of very early, early and late varieties will give you blooms all season until frost.


Seed Sowing & Growing

  • Sow Depth: 1” or 2.6 cm
  • Winter sowing technique (stratification) does not require additional seed preparation.
  • For early indoor starting or direct sowing nick the seed coat. Soaking overnight in water or hydrogen peroxide will also break dormancy. Plant only the seeds that swell from soaking and nick the ones that didn't.
  • Another option for early indoor starting is to nick the seed coat and roll the seeds in a damp paper towel and put in a plastic bag. When they start to sprout, plant in soil medium.
  • Typical germination is 10 to 20 days
  • Grow cool. Under 60ºF or 16ºC is best for the root development stage for 6 to 12 weeks. 
  • Use garden inoculants at sowing time.
  • Plant in sunny area with moist rich soil. Add compost and fertilize regularly. (I like to use fish fertilizer when they are small and a bloom booster fertilizer in later season.)
  • Space individual plants about 6 inches apart.
  • Light frosts will not damage plants.
  • Pinch the fourth set of leaves off to encourage side branching.
  • Water well in hot conditions.
  • Deadhead to keep the flowers forming. Cut flowers last over a week. The more you pick, the more flowers the plant will produce.
  • Cut the seed pods off if they start forming. Once the plant starts going to seed it is a signal to the end of it's life cycle.
  • Seeds & flower are not edible.
Thumb of 2012-12-31/Joannabanana/6acedc 2012-12-31/Joannabanana/1aa4db Thumb of 2012-12-31/Joannabanana/859c88
Late May (Average Last Frost is May 23rd, Started early indoors in March) Early July (Blooms have started) Mid September (After hail storms, summer heat and a few frosts, they are still going)


I hope this information helps you choose the best sweet peas for your garden.

Comments and discussion:
Thread Title Last Reply Replies
Sweet Peas by valleylynn Oct 12, 2017 6:14 AM 21

Explore More:

Give a thumbs up
Member Login:

[ Join now ]

Today's site banner is by lauriemorningglory and is called "Shamrock Leaves of Oxalis"

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.