When to sow?
Many of the articles that you read will advise you to sow in October. Some will in fact advise that sowing in October mimics mother nature.
The main benefit of October sowing allows the young plants to develop a well-established root system. This early sowing means however that you will have to plant out in late February/early March.
Sowing in October does not in any way mimic mother nature. Drop a sweet pea seed in the garden in September and it will not germinate until late March at the earliest.
What October sowing allows is germination without the use of excessive heat.
I have however, always sown in January. If plants are cared for correctly, then there is little difference to be had, with the exception that you plant out later and the plants flower later.
Ultimately, I believe it is dependent upon when you want your plants to flower. If you want an early display from mid-May to mid-July, sow in October. If you want a display from mid-June onwards, sow in January.
Many a good Sweet Pea grower, who sowed in January, have won the most prestigious award in Sweet Peas, the Daily Mail.
Prior to sowing, I fill a seed tray with multi purpose compost, give it a good watering and allow it to stand at room temperature for 24hours prior to sowing. At the same time I soak my seed over night on damp kitchen paper in a dish.
The following day, I check to see if any of the seed has swollen. This is relatively easy to detect as the swollen seed is usually twice its normal size. Any seed that hasn’t swollen, I take a sharp knife a place the seed between my thumb and forefinger. All Sweet pea seed have what looks like an eye. turn the seed 180 degrees away from the eye and using the sharp knife delicately take a ‘nick’ out of the seed coating.
I then sow the seed into the previously prepared seed tray, and lightly press the seed into the compost, to a depth of around1cm. Sow too deep and I find that the seed has a tendency to rot.
Back fill the seed, and keep at room temperature, covering the seed tray to block out the light. An ideal temperature of 18-20 degrees is ideal.
I dig my bed in the Autumn, as parts of my Sweet Pea bed is heavy clay. Exposing the clay to the winter allows the clay to be broken up, as the frost penetrates the wet clay.
There is a misconception that Sweet Pea’s require a lot of organic matter. I apply an organic composted farmyard manure, to a depth of 1inch – 1 1/2 inch in the spring, and fork this in well. The lighter your soil, you may wish to apply more.
There is no exact science regarding the use of fertilizers, as this is purely dependent upon your own unique soil.
I have known the same variety being grown yards apart that have produced completely different results.
The Sweet Pea is a legume, which in simple terms, means that it can produce its own nitrogen from its own environment. I therefore recommend the use of a balanced fertilizer as well as an additional top up with Potash.
Sweet Peas are also sensitive to acidic soils, and the soil they are grow in should be ph7 -ph7.3
Should you have an acidic soil, I recommend the use of hydrated lime, which should be applied to the soil around 6-8 weeks prior to planting out.
Young plant care
Once through, place the young seedlings into a cold greenhouse. Do not leave them at room temperature. The cold allows the plant to develop a strong root system, whilst keeping the tender shoot stocky.
Prick the young plants out into individual cups, usually 2-3 weeks after germination. Keep moist and in a cool greenhouse.
The young plants will stand several degrees of frost. However, if the young plants get frosted, do not allow them to thaw out quick, otherwise this will cause the plant to collapse.
Once the young plant has developed 2 pairs of leaves, nip out the head of the plant, to leave the 2 pairs of leaves. This encourages the stronger side shoots to develop.
Whilst the plants remain in the greenhouse, I keep the door open during the day, and close the door at night.
As I sow in January, I remove the plants from the greenhouse, towards the beginning of March. As the temperatures increase gradually through spring, this helps keep the developing plant stocky.
Layering is part of growing your Sweet Peas using the cordon method. Layering is the process of taking a plant that has reached around 4-5 feet high, removing the ties, laying the plant on the floor and allowing the plant to continue growing up a cane further down the row.
Some prefer to layer flat. This is a process where all ties are taken off each plant. The plants are then laid on the ground and the heads are allowed to turn naturally upwards over the course of the next 2 – 3 days. For me there are issues in this method.
Firstly, I have found that the heads of the plant rarely turn up at a cane, and you therefore either have to adjust canes, or wait until the plants are of a sufficient length to train them to a cane.
Another issue is that the young fleshy head is a big appeal to slugs and snails, and the longer they are close to the ground the more chance of them being attacked.
Finally, I find that the plants take longer to recover using this method. I find that it can take around 3 weeks to get flowers for show, as the stems are generally bent quite badly.
The benefits however is that you do not have to risk snapping a plant as you do with the other method.
This other method, which I prefer, involves the same principle as above, but instead of laying the plants flat, you tie them to a cane further down the row, and take them to a height of around 12-18inches.
This method should be done on a warm day if possible, when the plants are less brittle, which reduces the risk of them snapping.
As a result, the plants need less time to recover, and you can have blooms ready for a show in just over a week.
However, allow yourself a minimum of 2 weeks before a show to layer, as it can also induce bud drop. Layering triggers a large release of sap into the head of the plant, which can be too much and cause bud drop. Leave a couple of strong side shoots on the plant to allow the sap rise to be dispersed through the plant. Whilst this will not guarantee you will be bud drop free, it will help to reduce the impact of layering.