Sweet peas: which to grow and how to grow them
I’ve always prided myself on my sweet peas, but this year they have been exceptional. After a late start in June, they have zoomed up over 10 foot tall and my determination to control the number of stems each plant produces is equaled only by their determination to put out more. The long cool spring here in Victoria may have resulted in an abundance of aphids and a proliferation of fungal diseases, but it has also brought this wealth of sweetness. I’ve probably given away close to a hundred bunches so far this year.
When I first started growing sweet peas, I chose my seeds with two things in mind: the scent – because, as with the rose, what’s the point of a sweet pea without fragrance – and the name – because I was young and going through a vaguely romantic period. I have particularly fond memories of ‘Hunter’s Moon’, a beautifully fragrant white that I haven’t seen for years. Now, I am not quite so fussed about the names. I even regularly grow ‘Charlie’s Angel’, while drawing a firm line at ‘Alan Titchmarsh’. But scent remains a priority.
When I lived in central Scotland, I joined the committee of the local village flower show and flirted briefly with exhibiting sweet peas, but my heart wasn’t really in it. I couldn’t understand sacrificing scent for the sake of a long stem or a particularly fine ruffle, and so my entries always produced a barely disguised snicker from the judges. (Alan Bennett wasn’t kidding when he observed, ‘If you think squash is a competitive activity, try flower arranging’.) If, like me, you want to grow sweet peas for the scent, then you need to grow mainly grandifloras, either the old fashioned or the modern. You won’t win a trophy, but your house will smell divine.
Grandifloras and Spencer types
Lathyrus odoratus was native to Sicily, Southern Italy and the Aegean islands, and the modern sweet pea was developed from seeds that the Sicilian monk Francisco Cupani sent to friends and botanists throughout Europe in 1699. The grandifloras are the intensely fragrant old-fashioned sweet peas that were subsequently developed by Henry Eckford and others in the late nineteenth century. Their wonderful fragrance makes up for the fact they have relatively short stems and small flowers, sometimes only two or three flowers per stem.
It was from these grandifloras that, in the early twentieth century, Silas Cole, gardener to, yes, that Spencer family, produced the Spencer types which are most prevalent today. They have larger and frillier flowers, and more of them, and they have longer stems. Because they are grown with cutting (and exhibiting) in mind, they don’t have as many side shoots and therefore less flowers per plant, but, more importantly, the fragrance is often slight or even non-existent. I do, nevertheless, always grow some of these to add volume and frill to bouquets.
There are also an increasing number of modern grandifloras to choose from, varieties that combine the better scent of the old-fashioned grandifloras with longer stems and/or bigger flowers. My all-time favourite sweet pea, ‘Matucana’, falls into this category.
I look on mixed packets of sweet pea seeds with a deeply suspicious eye. When I have succumbed, I’ve been disappointed. Anyway, I like being on first name terms with my plants, and if there’s some particularly good ones I want to know who they are so I can grow them again.
My standard choices
There’s such a choice that I like to experiment with different sweet peas every year, but there are three varieties I always grow because of their exceptional fragrance. Having said that, smell is a funny thing, and not everyone would necessarily agree with my choices.
Well … except in the case of ‘Matucana’. This the one sweet pea everyone should grow. It is a maroon and violet bicolour that everyone agrees has a sensational scent, probably the most fragrant sweet pea in the world. Although many sell ‘Matucana’ as the original sweet pea, it isn’t. It is a modern grandiflora found in Peru. ‘Matucana’ is not just the best scented, but possibly also the most prolific, producing a phenomenal number of flowers and more than making up for the fact that these flowers are rather small and come only three to a stem. It is also very heat tolerant.
In Scotland, Spain and Canada, this old-fashioned grandiflora has always been the first sweet pea in my garden to flower. ‘Prima Donna’ is a soft pink with an excellent scent and quite long stems for an old-fashioned. It has very small flowers, though, often only two per stem.
This modern grandiflora is a lovely picotee, with a white ground and purple edge and purple whiskers leading to the throat. Very free flowering with strong and long stems. To my nose, its scent is one of the strongest and most beautiful of all.
Where to buy
Part of the fun of growing sweet peas is choosing which ones to grow from the huge number of varieties on offer. These are some online catalogues I recommend for browsing and buying.
Roger Parsons holder of the National Collection in the UK and probably the largest selection of sweet peas in the world.
Floret Flower Farm in the US has a good selection of individual varieties.
Ardelia Farm has an amazing selection and specialises in the production of rare sweet peas seeds.
As a cut flower
Sweet peas don’t last long once cut, but there are a few things you can do to extend the vase life. Cut while there is still at least one unopened flower at the tip, keep them away from fruit and from other flowers (they respond badly to ethylene), and give them a little sugar or flower food.
How to grow
Here in Victoria, in 2021/2 I followed the schedule for sowing and planting that I’d had in central Scotland and it worked perfectly. I sowed one batch on November 15 and another on January 7. But I realised the next year I could do it earlier. I sowed the first batch instead on October 28 and got even stronger plants.
Germination: sweet peas need darkness to germinate. No chill period, no soaking, no chipping required. I sowed 1” deep in long 6” pots, 6 seeds to a pot, covered them with moist newspaper and put them in the warm cupboard where we have the furnace and the hot water heater. When most had germinated (check frequently!) I took them out and got them into a cooler environment (around 19°C) in the light. After a couple of days to adjust, they were put outside in a cold frame. They grow best at 3-10°C. It’s preferable to keep them frost free, although they should handle a little bit of frost as long as you let them warm up slowly (don’t let the sun defrost them).
Planting: I prepared the ground in autumn, adding compost and manure to a trench and then setting up a support system of canes. Planted the first batch out in early March, the second in late March. I intended to take the lead stem out when they were about 18” high, as side shoots give better, stronger flowers … but I forgot. I fed with weak manure and comfrey tea once a week after the first flowers came out. Then, just keep picking; if you let them set seed, that’s it, they will stop flowering.
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