How to Grow Sweet Peas | Blog Posts | Forum

Growing sweet peas is not tough. As with many annuals, you could just poke a seed in the ground and wait. You would actually get pretty good results too. But this is certainly not the way too get the best results. So how can we improve our chances of success?

We first need to define what we mean by "success". For the majority growers success can be a measure of germination rate, flowering period, number of flowers, length of the stems, uniformity of the blooms and so on. We'll look at how to achieve these in more detail below.

When to Sow?

There are a number of options open to the sweet pea grower. In short, autumn sowing is preferred, but is by no means necessary – most gardeners will achieve satisfactory results by sowing in spring. See Sweet Peas – When to Sow for a full discussion. Regardless of when you sow your seeds, the considerations that follow hold true.

Choosing Seeds and Varieties

Your needs and location will dictate this. Commercially produced seed is always favourable, as it ought to be free of rogues and the germination rate should be fairly dependable. That's not to say it isn't enormous fun saving and sowing your own seeds – because it is! But if you want consistent colours and reliable germination, commercial seed is the way to go.

Most types can be grown in the UK and Western Europe without much consideration, but for the US where the days are hotter, Cuthbersons or Royals are a good choice. Both were derived from Spencers by the Ferry-Morse Seed Company and are better able to stand the higher temperatures of an American summer.

How to sow?

There are really no right and wrong answers here. Different growers will report differing levels of success – and what one grower swears by, another may dismiss out of hand. I think it is important to bear in mind a few undisputed facts which will allow us to form a framework – sweet peas like sun, deep soil, plenty of water and freely draining soil – eveything else is just to help the germination process along and improve the chances of getting healthier seedlings, and ultimately more and better flowers.

Having selected our seeds, we need a growing medium (our soil or compost) and something to put it all in. I have obtained good results using Westland John Innes Seed Sowing Compost in 5" Rootrainers.

As an alternative, if you want a way to put your empty toilet rolls to good use, save them throughout the year and these can make good starter pots – just plant the seedlings along with the pot in the growing site and you'll avoid root any potential root damage. The pot will just rot away over the summer in the ground. You can also buy specially created sweet pea tubes that do the same thing, but my preference is the Rootrainers, just for the convenience of being able to move 32 cells at a time (I'm also incredibly clumsy, and find myself knocking the tubes over way too often). In the absence of any of the above it is possible to use 3" pots, but the restricted depth may hamper root development.

Many growers (myself included) find germination can be improved by chipping the seed coat. Using a sharp knife, cut away a tiny bit of the hard outer coating of the seed on the side away from the eye. This will promote the uptake of moisture by the seed, and hopefully provide more reliable and uniform germination. Plant the seeds about 1-2cm deep and cover. The soil should be kept moist, but not soggy – the seeds can easily rot if kept too wet for prolonged periods (some varieties are more susceptible than others).

Now you have to wait. Germination can occur anything between a few days and a few weeks after sowing. It is possible to move the seeds to a warm room to encourage faster germination, but I would caution against it. If the seedlings are started in a warm room, they will rocket out through the soil in search of a good source of light, becoming weak and leggy, and it happens very quickly! Better to wait and bring the seedlings up as hard as possible. It is beneficial at this stage to keep the soil consistently moist. Don't be afraid to give them a good soak if the weather has been warm.

Planting Out

When the seedlings reech 4-5" tall, its time to plant out (unless you are over-wintering). Pinching-out first is an option, but I have never found it to be necessary – the side shoots tend to come anyway. Over-wintered plants should be tolerant of all but the hardest frosts. Spring sown plants may need a little protection if frosts persist. Protect seeds and seedlings from slugs, mice and pigeons.

Sweet peas should be planted in a sunny position, although they can do well on a shady wall. As long as they get plenty of light they should do well. The soil should be rich and well drained, and preferably deep. It is not necessary to make any special preperations, but a well worked spot with plenty of organic matter will reward you with better flowers and a longer season. The perfectionist would do well to read Bernard R. Jones' book [ref] (sadly out of print – but readily available from second hand book shops) or Graham Rice's "The Sweet Pea Book" [ref] for a full discussion on soil and location.

Care

From now on, your sweet peas will require lots of water, and the occasional feed (use a general purpose plant food formulated for flowers). Use supports in the form of canes, cane wigwams, strong netting or a trellis. Keep an eye out for greenfly or any signs of fungus and treat as necessary. Soon your plants should start to flower! Cut the flowers regularly to prevent the plant going to seed – when it does it will no longer produce flowers.

Final Thoughts

The guidance provided here is pretty general. Your local conditions, budget, time and growing site may have the final word. Remember, all sweet peas really need is a good sunny spot. If you don't intend to exhibit your flowers, you will get satisfactory results as long as the plants get plenty of sun and water. If you do intend to exhibit, and haven't already done so, joining a specialist society will help enormously. In the UK the National Sweet Pea Society is the way to go. The members are very generous with their knowledge and will gladly give support, advice and encouragement. The books listed below are highly recommended if you want more detail on preparing your site, cordon growing, soil preparation etc.

Bibliography

[bibtex file=bibliography.bib key=jones1986]
[bibtex file=bibliography.bib key=rice2005]

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