There is a long-standing tradition to plant your Sweet Pea seeds on St Patrick’s Day (17 March) in Australia. However, this is far from the best time to plant your seeds.
You need to wait until the soil temperature drops to around 15C before you plant your Sweet Pea seeds. This means that the best time to plant your seeds is from mid April.
Warm Temperate and Warmer Areas of Australia – We recommend you plant your Sweet Pea seeds from mid April to mid May for the best results. As per our information on “How to Grow Sweet Peas”, you need to plant your seeds so that they have finished flowering before the humidity sets in. Our Early Flowering varieties are recommended for this area.
Cool Temperate Areas of Australia - We recommend you plant your Sweet Pea seeds from mid April to early June for the best results. Since Sweet Peas are best suited to cool temperate conditions, all Lathyrus varieties are suitable to be planted (except the species) during this time.
Since Cool Temperate Areas of Australia generally don’t have a problem with humidity, you can also sow Sweet Peas in Spring. Here in Tasmania, I plant a second crop during October and November for a summer to autumn flowering.
Spring is the time to plant your Lathyrus species seeds in both warm and cool temperate areas of Australia.
Please note we do not recommend soaking your Sweet Pea seeds before sowing them.