In the short days of January it is cheering to note that daylight hours are increasing and thoughts can turn to this summer’s flowers, some of which may be sown now.
My personal favourite, both for garden display and as a scented cut flower, are sweet peas. If you have a cool greenhouse, seed can be sown in a propagator; early sowing will give you earlier flowers than seed sown outdoors in the spring. Temperature needed for germination is 10-15 C/50-60 F.
I used to carry out trials for the National Sweet Peas Society and we would sow seed singly into 3.5inch/9cm pots. Seed has a hard coat and chipping the seed coat with a knife to remove a small section of it is said to improve the rate of germination by allowing moisture through.
We had so many seeds to sow that we didn’t have time to chip the seed coat, as many text books recommend, and found germination to be perfectly satisfactory.
A multi-purpose compost is suitable. If you prefer not to use peat, there are several peat-free and reduced peat composts now available. At Clumber we use peat-free composts, based on coir, a waste product from Sri Lanka which has to be transported several thousand miles to get here. We’ve begun experimenting with composts based on locally produced green waste.
At 15 C/60 F germination should take place within a fortnight. When seedlings have formed their second pair of leaves, pinch out the growing tip to encourage side shoots to develop. Grow the seedlings on in a cool greenhouse or cold frame. A couple of weeks before planting out, gradually expose the seedlings to lower temperatures to acclimatise them to outdoor conditions, a process known as ‘hardening off’.
Plant out in April into ground that has been prepared by digging and incorporating well rotted manure or compost. Sunny, sheltered sites will suit them best.
The choice of varieties is enormous. The modern Spencer varieties, with frilly edges to their petals, come in many colours and petal markings. Pale pink ‘Champagne Bubbles’ and bright red ‘Barry Dare’ are reliable. We usually grow a few of the old fashioned ‘grandifloras’, raised in the late Victorian era.
Don’t be misled by the name, the flowers are not especially large, but most have a strong scent. The red and white ‘Candy Stripe’ and bright orange ‘Henry Eckford’ won’t disappoint.
There are also lower growing strains which need no or little support. ‘Jet Set’ reaches a height of 36ins/90cm, whilst the ‘Dwarf Explorer’ strain is ideal for pots and containers. Taller growing varieties will need supporting. At Clumber we favour ‘wigwams’ made from beech or birch brash, but wooden trellising, canes or plastic pea and bean netting will also do the job. For garden decoration, the wigwams or obelisks look great in a mixed border, alongside shrubs, perennials and other annuals. As soon as blooms have faded, cut them off. This will encourage more flowers to be produced.
In Clumber’s Long Range glasshouse we’re growing ‘spring flowering’ sweet peas. Seed was sown in early October and they should be in bloom in February.