How to Grow Sweet Peas
Updated: May 20, 2021
For most Sweet Pea varieties, seeds can be sown in both autumn and spring. If otherwise, this is stated on the seed variety’s profile sheet.
In Australia we sow seeds from mid April to June. If you live in cool temperate area like Tasmania you will also be able to sow in spring.
In cooler regions, seeds can be started indoors approximately two weeks before you would directly sow the seed outside.
We don’t recommend soaking before sowing, unless stated for that particular variety.
Nor is the use of heat mats to assist in the germination recommended.
Ideally sow your Sweet Pea seeds one seed per pot, 2cm deep. Note: pot selection is important: they need to be approximately 10cm in height to enable the seedling to establish strong root development.
Or you can direct sow your seeds.
Water once at the time of planting – whether in pots or the garden. Do not water again until the seed germinates. However, it is important to keep the soil moist, not wet until germination. Sometimes, this does require additional watering the sown seed.
Make sure you harden the potted seedlings off for at least a week before transplanting into the garden.
Sweet Peas prefer alkaline soil that is well drained.
Sweet Peas require their roots to be cool and moist while the rest of the plant basks in full sun. A great tip is to plant annuals around the base of the plant to shade the roots.
The standard way to prepare your site is to dig in a generous amount of compost, sprinkle over some blood and bone and tomato fertiliser and thoroughly mix through. However, I prefer to dig in “Whoflungdung” and mulch with sugar cane.
Take care not to disturb the seedling’s roots, as Sweet Peas DO NOT like having their roots disturbed. If possible, place the pot on its side in your hand and gently slide the seedling out and into its permanent location. Distance between each plant should be no less than 30cm.
Germination can take seven to 15 days, depending on the variety and soil temperature. Some varieties like the species can take longer to germinate.
Keep soil moist but not wet. It is recommended you water only in the morning.
There is no need to fertilise if you have prepared your planting area as per our above instructions. Additional fertiliser may result in the plants producing more foliage and less flowers.
Mulching your Sweet Pea plants helps keeps their roots cool and damp.
Growing annuals like violas with your sweet peas will also assist in keeping their roots cool.
Most Sweet Peas, except for the bushy varieties eg dwarf and some species, will need support as these are climbing plants.
At least two metres of climbing support is required, but some varieties can grow taller. The Gawler varieties can grow to 3m.
Structures for climbing can be as simple as chicken wire, netting, or teepees. The main thing to remember is to leave room for growth and sturdiness for the weight of the plant.
Enjoy the Flowers
Pick the flowers often as this increases the number of flowers the plant will produce.
Removing seeds pods prolongs the flowering.
Flowers are best picked when the bloom at the bottom of the stem is just beginning to open. Also pick flowers during the coolest part of the day.
Adding sugar to the water will extend the life of cut flowers.
Pests and Diseases
Slugs and snails are your main enemy. We recommend using beer traps. (see our website for our snail / slug traps). Please note not to use copper near your Sweet Peas.
Powdery mildew and rust can be issues. Keeping air flow around your plant and watering (without wetting the foliage) only in the morning can help to reduce the occurrence of these problems.
If you are in an area with high humidity, plant your seeds so that they have finished flowering before the humidity sets in. Our early flowering varieties are recommended for these areas.
Storing Your Sweet Peas Seeds
Sweet Pea seeds can be stored in the freezer. Place them in a container that will keep the seeds dry. Seeds stored this way will not age and can be defrosted and refrozen without any harm to the seed or reduction in the germination rate.