Sweet Peas are stunningly beautiful yet delicate flowers, some of which carry a gorgeous scent. I have been growing them for a number of years with mixed success!
There a number of different ways to grow them and different times of year that you can sow them. Depending on what you are growing them for, whether it is for cut flowers in the house or for exhibition, will determine when you sow them.
I tend to sow my Sweet Pea seeds between October and November, this depends on how much space I have in the greenhouse as I have just started growing a few late Chrysanthemums! In 2012 I sowed mine in early November. I sow mine in seed trays of multi purpose compost covering lightly with compost and then giving a good soak before placing on the hot bed. I donít give them too much heat but somewhere around 55 degrees is ample. After around a week to ten days you will see the seeds begin to germinate. Once they are about an inch tall I prick them out into individual growing tubes. Up until now I have just used multi purpose compost but I think I will start adding some Perlite from 2013. These are then put into trays of which hold twenty grow tubes and put into the polytunnel which is unheated. After a few weeks the young plants will have produced two pairs of leaves. At this point I remove the growing tip from each plant. This will encourage strong side shoots from the lower leaf joints. For a reason unknown to me the flowers that are produced from these side shoots are far better than from the main growing stem.
After a few more weeks you will see the new side shoots appear. Depending on the weather I either leave them in the polytunnel or they are put into a cold frame, however, the last few years I have left them in the polytunnel to keep the worst of the weather off them.
I prepare the plot by rotovating the ground at the end of the year and again, weather allowing, at the end of February. Once I have done so I dig a trench for each row and add a thin layer of chicken manure, not too much as itís quite strong stuff and Iíve seen the devastating effects of over strong manure on the roots of young plants. I then rake the soil over and apply a generous amount of fish, blood and bone.
I then space out 7 or 8 ft canes approx 6Ē apart in rows of a hundred. This year Iím experimenting as I am aiming to compete in the Championship class at the National Sweet Pea Show in Christchurch. This calls for twelve distinct vases, 15 stems in each vase. Iím growing approx 35 of each variety and have 17 varieties to choose from.
My rows would normally be just 2 feet apart but I have decided to cover them this year due to the terrible weather we have had just before the shows over the last few years. I have therefore decided to utilise the covered Dahlia plot and will be planting my rows 4 ft apart in order to plant my Dahlias between the rows. Whether or not this will work, only time will tell.
Once the plot is ready and the plants are looking strong and healthy it is time to plant them out. This can be done anytime between March and May depending on the weather. When they are all planted I water them in well. Around two weeks after planting I check every plant and select the strongest side shoot and tie this against the cane with a paper covered twist tie. I grow them on a single cordon to maximise the energy to one stem. The remainder of the side shoots are removed using a sharp pair of scissors. After each variety I clean the scissors in a weak bleach solution to minimise the risk of spreading any disease between the varieties.
The plants will be slow to get growing at first but once they start they will grow rapidly and will need tying up on a weekly basis. As the plants grow you will see numerous new side shoots from each leaf joint. These must be removed and can usually just be rubbed out with your thumb. You will also see thin, curly tendrils growing from the ends of the leaves. Naturally, these would attach themselves to the cane but in order to direct all the energy into the main growing point and the forthcoming flowering stems, these must be removed. Again, a sharp pair of scissors will be perfect for the job.
Once the plants reach around 3 ft high you will begin to see flower buds forming at the top of the stem. However, do not worry if these fall off before the stem matures as it is likely that we will still be experiencing cold nights. Sweet Peas are very delicate and if the night time temperature drops below around 8 degrees centigrade then the buds will not form correctly and will fall off leaving nothing but bare stems. This has been an increasing problem over the last two years due to exceptionally cold nights right through the early part of the summer. Donít let this put you off though as the rewards for all the hard work will pay off. Before long you will be blessed with an abundance of flowers on long stems. In order to keep the plants flowering you must pick the flowers regularly, in the same way that you pick runner beans. Sweet Peas donít like to be too wet but in a dry spell they will need watering and feeding. I generally, use a balanced feed. Later in the season you might find them suffering from leaf scorch which is thought to be caused by a magnesium deficiency, this can be helped with a dose of Epsom Salts.
Before too long the plants will be upwards of 5ft tall and this is where youíll have to decide what to do with them. You can either let them continue growing, which within a week or two will be reaching the tops of the canes and out of reach, or you can layer them. Layering them is quite a task but is something that you will have to do, especially if you plan on exhibiting them. The belief is that the flowers are somewhat better when the plants are 4 to 5ft tall, although it might just be that they are easier to reach! In order to layer them you have to untie each plant, and then lay them down along the row and then re attach to a cane further down the row. I have left 5 spare canes at the end of my rows in order to do this as my rows are far apart. I start by untying several plants and laying them down away from the row. Then I begin untying each plant then laying them down as near to the ground as possible and then re attaching to the furthest available cane. The amount of plants that you have to remove at first will depend on what stage you Sweet Peas are at. It will often depend on when your shows are as the plants will usually take around two weeks from layering to be back producing super quality flowers on long straight stems. It is also possible to layer them more than once depending on how much time you want to keep them flowering for and when your shows are. Itís a bit like Formula 1 racing; itís either a once stop or two stop strategy! Due to the amount of plants I am growing this year I would think that I will be layering them just the once about two weeks before the National.
It is possible to pick Sweet Peas for several months, two years ago I grew a few in my polytunnel and was able to pick fresh flowers from April to September. This year so far its been so cold that although Iíve planted my first few in the polytunnel I canít see there being any ready until the end of May at the earliest. As for the ones outside, well as soon as my last show is over Iíll be pulling them all up to make room for the Dahlias!