A beginners guide to growing sweet peas

Sweet peas are the plant that sold me on the romance and reward of growing flowers.

“Of anything I will ever grow; sweet peas will have a special, delicious spot in my gardening lifeline. It was these friendly, uncomplicated creatures that became my ‘first’ flowers. First flowers to greet me driving in the gate, first flowers to pose for me in the soft morning light, first blooms I could cut for my home and experience the joy of taking bunches to give to others," as I wrote in my book Petal Power.

“ If there was a kickstart for growing flowers, you’ve found it here.”

Every year, I watch my crop shrivel and succumb to powdery mildew as I lose the race of regular deadheading and no doubt underwatering, underfeeding and general summer heat.

One look through my camera roll reminds me that the grim end of their flowering is fully substantiated by the glory of the height of it. For seasoned gardeners, this all sounds familiar as part-and-parcel of a seasonal garden, as a beginner, sweet peas are like a case study for how this growing thing all works.

I’m the first to admit that writing a book about gardening as a beginner, just four years into my own adventure, was a little ambitious. However, Petal Power is a diary of sorts, sharing the early successes of growing in my own garden with a lack of experience and demystifying the knowledge that I squeezed from books, the internet and generous gardeners who have given me their time.

It has been entirely by accident that I have discovered the advantages of getting sweet peas going in autumn, as opposed to the obvious spring planting. Last year, I let my rampaging wall of sweet peas dry their seeds on the plant, watching as the pods popped and dropped their gold to the garden below. I pulled the crumbling vines off the fence and walked away – paying little attention to what would happen next.

By June, I had lush vines halfway up the fence. By September, I had a pickable crop of blooms.
While it was massively rewarding to have flowers so early, my vines had largely given up the ghost by the end of December, which taught me that planting a second crop in springtime would have given me the chance of blooms further on through the summer season.

With all this in mind, I have collated a simple guide below to support new gardeners in growing sweet peas this year too:

• Sweet peas like a spot with good, rich soil, lots of full sun exposure and somewhere you can easily and regularly water during flowering.

• As they are vines, offer them something to climb or ramble over.
  We have used steel foundation mesh stapled to our wooden fence, but bamboo/branch teepees, regular trellis and even stringing taut, strong cord on a frame will be gratefully received by their curly little stems.

• Consider staggering your planting.
  Have a go sowing some seeds directly in place now in autumn, leaving space to sow again in springtime. Your climate will dictate how successful your over-wintered crop will be, but it is a great experiment. Alternatively, you could raise them undercover in winter, ready to pop them in as strong seedlings once the weather warms up.

• If you have left a crop to self-seed, thin out your enthusiastic seedlings as they mature over winter. I allowed all mine to grow last year and their overcrowding inhibited flowering and exposed them to powdery mildew much earlier than normal.

• Once your seedlings have four sets of leaves, gently “pinch” out the central stem between the top set of leaves to encourage the development of bushier plants.

• Sweet peas are the perfect example of a “cut and come again” annual, which means if you regularly harvest their blooms, or deadhead before their seedpods form, they will push on to keep producing flowers for as long as their vines are healthy.
  Every year, I follow the great Monty Don’s advice of harvesting every open bloom and partially open bud on the vine in 1 -2 times a week. This will make a massive difference to your continued crop of flowers.

• Sweet peas are greedy feeders so top up their beds with liquid fertiliser a few times over the flowering season. Better yet, you prepare the beds you are sowing into with compost and sheep poo in autumn to give them a great start.

• Sweet peas are very much a “head in the sun with moist feet” type of plant. They suffer almost instantly if too dry and the stress will often result in the arrival of the dreaded powdery mildew.

• To harvest your own seeds, you need to let the seed pods mature and dry on the vine. This means coping with the pretty dismal, gnarly mess of dying vines for a while. Mature pods are cardboard brown and easily crack open.

Lastly, don’t fret if you feel you have missed the boat on autumn sowing because “life” has gotten in the way. A great way to grow sweet peas for the first time is to simply swing by the garden centre this spring and pick up the very affordable pods of healthy seedlings ready to simply plug directly into your garden.

This is how I got going and how I caught the bug.

This article was first featured in my Stuff ‘Homed’ gardening column for beginners and The Press on May 13th 2021
All words are my own and images are my own, photographed in my own Christchurch garden.