Harvesting, sowing and growing sweet peas (Lathyrus odoratus)
Sweet peas (Lathyrus odorous) produce seeds in large, easily handled pods and as with all seeds they should be collected when they are fully ripened. This should be done on a dry day and once the pods have turned pale brown and rattle.
Dry sweet peas seeds by laying them on a greenhouse bench, on a warm window sill or in an airing cupboard. The pods should be split to release the seed. If they do not split they may be encouraged to do so by running the edge of a fingernail along the pod seam and then spreading the pod open with fingers, alternatively gently crush the pods. Once the seed has been released, any material (chaff) attached to the seed should be removed as this can harbour moulds, pests and diseases and lead to damping off.
The seeds should be stored in labelled paper packets in an airtight container with some descant to remove excess moisture and placed in a refrigerator at 5°C until ready for use.
The seeds can sowed in late Autumn in order to produce flowering potential, however they may be sowed anytime up until spring.
Sweet pea seeds may be pale buff in colour or darker. In order to aid germination the darker seeds should be niched with a sharp pen knife opposite the eye. The seeds should not be soaked to help avoid rotting.
The seeds can be sowed in seed trays approximately 2-3cm apart in a loamless potting compost with 20% added grit, or a standard seed compost, and then covered with 1cm of the same compost.
They should be watered in and then covered with clear polythene and kept at 15°C until germination.
Once they have germinated they can be transferred to a cold frame and once they reach about 3-5cm they should be planted out singularly in 9cm pots. If they have not produced side shoots by mid-winter the tips can be pinched out to encourage a multi-stemmed growing nature.
The cold frame should be kept open as much as possible to harden the plants off, but closed when temperatures are to drop below -2°C.
A dilute liquid feed can be given in late winter, following the instructions on the bottle for dilution rates.
To control aphids, lacewings and ladybirds can be introduced along with the biological control aphidius spp. These little mini wasps parasitise the aphids by laying their eggs in them.
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