drawing of sweet pea cane and string cordon frame

Design for easy-to-make string cordon on cane frame

Sweet pea stem with tendrils

Tendrils of nearby plants can distort and bend flower stems

I love growing sweet peas on wigwams in an ornamental bed. Bamboo tripods and obelisks create height and structure in a flower bed and when festooned in fragrant sweet peas the effect is undeniably stunning.

However, when I started growing sweet peas in greater quantities for cut flowers I soon discovered the tripod or obelisk structure compromised the quality of the flowers.

Plants on an obselisk grow upwards and inwards, eventually converging at the top in a tangled mess.  The ingenious tendrils of the sweet pea reach out and grab whatever they can for support.  Where the tendrils wrap around a nearby flower spike, the stem can be bent and curled in the process.

I decided that I would start growing sweet peas in my vegetable patch, and that I needed to attempt to grow each plant more vertically and more widely spaced from its neighbours.  It’s possible that it’s been done by others of course, but I developed my own take on a cordon method which I’ve set out below with useful photographs.

If you are trying to decide which varieties to grow for cut flowers you may also be interested to read my article on choosing the perfect bloom for you.  Click here for my article on sweet pea varieties including some stunning pictures of my favourites for scent, colour, pattern and even the show bench.

flake sweet peas

A slection of choice sweet peas including ‘Nimbus’, ‘Night Sky’ and ‘Wiltshire Ripple’

My take on the cordon method – using fewer canes

sweet pea seedling on string

It is easy to twist string around a sweet pea seedling – after which it will grow straight upwards

Professional growers and exhibitors for show tend to grow sweet peas as cordons – straight upwards and usually one plant per bamboo cane.  The advantage of this is that each plant can be suitably spaced, won’t interfere with its neighbours and can easily be inspected for spent flowers.  The cut flower grower’s enemy is flowers going to pod. Seed-set compromises flower productivity.

As I grow 50 or so plants a year I decided that investment in 50 new individual canes was beyond me, as was the ability to store so many canes.

My solution was to build a structure which used fewer canes and could support vertical strings up which the plants could be trained.

One major advantage of string is that it is very easy to train the plant upwards.  Sweet peas are fairly robust, but can bend or even break if roughly handled.  Tying stems to canes is fiddly, whereas it is very easy to gently twist a taught string around the growing stem.

What you need

To create each 2.4 metre long section of support frame you will need:

  • 8 2.4 metre bamboo canes
  • A big ball of gardening string
  • Sharp knife or scissors to cut string.

This year, to support 50 plants, I built three 2.4 metre sections, connected together in one long line.  This runs along a thin strip in between a line of asparagus and the edge of a raised bed and is an excellent use of a narrow space.

How to build

Bamboo tripods

Bamboo tripods set a cane’s length apart

  1. Start by pushing three bamboo canes straight into the soil in a triangle.
  2. Gather the the canes together at the top to form a tall tripod.  I start with a clove hitch over the top of one cane and then loop the string round each cane in turn a few times before tying the two ends of string back together.
  3. Lie a cane along the ground from the first tripod to gauge where to site the second tripod and repeat the steps above.
  4. Sandwich a cane horizontally between the crossing tops of the two tripods.  If this is not firmly wedged in place, tie on with string.
  5. Secure a second cane horizontally just above ground level.  This will need lashing to one of the vertical canes of each tripod.  I used a method called square-lashing as this is very strong.

    Square lashing to secure two canes

    Square lashing is a good technique for securing a horizontal cane to a vertical one

  6. Take your spool of gardening string and place a pencil through the middle.  Secure the end of the spool to the bottom cane at one end of the structure them, holding the pencil at both ends, run the string up and over the top horizontal cane, back to the bottom and continue unspooling to create a zig-zag of string along the length of the structure. Cut the string and secure at the end
  7. Don’t worry if the strings aren’t fully taught across the length of the structure.  It’s difficult to achieve as canes are rarely perfectly straight and it can be difficult to keep the string tentioned. The sweet peas will climb regardless.

How to plant your sweet peas

  1. Prepare your soil by digging in some homemade compost along the line you want to plant.  I added granules of chicken manure too to give the sweet peas extra oomph.
  2. Space your sweet peas 10-15cm apart along the base of the structure.  Dig a deepish hole with a trowel, tease the sweet pea from its pot and plant securely.
  3. There is usually a gap between the sweet pea and the start of the strings.  If this is the case I place a few twigs around the plants to support them until they reach the strings
  4. Once the sweet pea reaches the string it will probably start climbing up of it’s own accord.  If they flop, grab the string just above the growing stem and twist it gently around.
  5. Once they get established, the sweet peas should need no further help and will scramble upwards giving you a long harvest period of strong straight stems.
Sweet pea on a string cordon

Sweet pea ‘Price Edward’ growing strong and straight from a string cordon

Ready to grow?  Read my handy guide on choosing sweet pea varieties for colour, scent and structure.