Sweet peas (Lathyrus odoratus) are cherished annual flowers, celebrated for their delicate, ruffled blooms and captivating fragrance. These climbing vines are a favorite for cutting gardens because they produce an abundance of flowers over an extended period. To maximize the bloom season and ensure the longest possible display indoors, gardeners must understand the precise moment to harvest and the proper techniques for post-harvest care.
Identifying the Ideal Picking Stage
The timing of harvest influences both the longevity of the cut flower and the continued productivity of the plant. Sweet peas should be picked when the flower spike reaches a specific stage of maturity, balancing open blooms and closed buds. The ideal moment is when two to four of the lowest flowers on the stem are fully open, while the terminal buds at the tip of the spike remain closed but show color. Harvesting at this stage ensures maximum vase life, as the buds will continue to open indoors.
The most important factor in keeping sweet peas flowering is “cutting and coming again.” The plant’s biological purpose is to produce seeds for the next generation; once it forms a seed pod, it signals the plant to cease flower production. Continuously removing spent flowers and emerging seed pods prevents the plant from completing its life cycle, forcing it to redirect energy into producing new flower spikes. If a single seed pod is allowed to develop, the vine’s flower production can dramatically slow or stop, ending the bloom season prematurely.
Executing the Clean Cut
Harvesting the sweet pea stem requires a clean technique to prevent plant damage and maximize the cut flower’s ability to absorb water. Use a pair of sharp, clean snips or shears, as a dull blade can crush the delicate stem tissues. A clean cut ensures the vascular system remains open, facilitating immediate and efficient water uptake.
The cut should secure the longest possible stem length, which is desirable for arranging. The location of the cut is also important for the plant’s future growth. Stems should be severed right where they meet the main vine or just above a set of healthy leaves, which is known as a leaf node. Cutting above a node encourages the plant to quickly initiate new lateral growth, leading to the next flush of flower spikes.
The time of day for cutting also impacts the stem’s hydration level and subsequent vase life. Stems are most turgid (full of water) in the early morning or late evening when temperatures are cooler and the plant has rehydrated overnight. Harvesting during the heat of the day, when the plant is actively transpiring, can result in immediate wilting and a reduced display life.
Maximizing Vase Life
Once the sweet pea stems are cut, immediate post-harvest conditioning is paramount to extending their vase life. These flowers are susceptible to dehydration, so the stems must be plunged immediately into deep, cool water. This rapid hydration prevents air bubbles from forming in the stem’s vascular system, which blocks water uptake and causes the flower to wilt.
All foliage that would sit below the waterline must be removed before placing the flowers in the vase. Submerged leaves rapidly decompose, fouling the water and creating a breeding ground for bacteria. These microbes clog the stem’s water-conducting tissues, shortening the flower’s life.
To prolong the display, the vase should be kept in a cool location, away from direct sunlight and any strong drafts. Sweet peas are sensitive to ethylene gas, a natural plant hormone released by ripening fruit. Keeping the vase away from fruit bowls prevents accelerated petal wilting and flower drop. Changing the water daily, or using a floral preservative, provides a fresh water source and inhibits the growth of harmful bacteria.