Heat-resistant climbing types, and bush types specially developed for bench growing rather than ground beds, make it possible to grow this delightful cut flower in a small greenhouse. Seeds are available for winter-flowering and spring-flowering varieties which have been developed to produce true commercial-type large, long-stemmed, deliriously fragrant flowers in almost any color: white, pink, salmon, rose-cream to crimson, even dark blue.
Dwarf varieties specially developed for shallow planting make it possible to grow sweet-peas in benches or pots. Sweet-peas are a cool crop; they must have plenty of ventilation to keep the temperature under 65 F during the day if possible. Water well in sunny weather. Seeds germinate more readily if soaked in water overnight before sowing. Plant seeds directly in benches where they are to grow, in a mix of 3 parts garden loam and 1 part well-rotted manure. Plant a row across end of bench at gable end of greenhouse and provide strings or wire from bench to greenhouse roof to support the vines.
When a vine reaches the roof, it may be slipped down the string to allow additional space for growing, or it may be pinched off to restrict growth. Seeds may be sown two or three to a peat pot; plant pots in the bench when a good root system has been established. Transplant the new dwarf types to a pot for growing as pot plants. The new heat-resistant varieties provide flowers into warm weather. For flowers in December, sow seed in September. An October sowing will provide cut flowers through May. When plants are at least 1 foot high, use a complete fertilizer about once a month, but only in sunny weather.
Overfertilizing in dull weather may cause buds to drop, as may over-watering and sudden changes in temperature. Do not crowd plants, provide good ventilation, and you will be rewarded with many blooms for cutting.
Cuthbertson's Floribunda Mixed, 5 to 6 blooms to a stem; 'Lois', rose-pink on white; 'Jimmy', best scarlet.