How to Grow Sweet Pea Flowers in Zones 9 and 10

If you have ever wondered how to grow sweet pea flowers in Zones 9 and 10, do not worry; you are not alone! This flower is often mistakenly planted much too late in the year in Zones 9 and 10, yielding little to no blooms before it burns up. Many beginning gardeners get enticed by the stunning blossoms and the amazing fragrance of sweet peas in the springtime and think they have time to plant their own. Well, do not make that mistake! In general, once you see sweet peas blooming in Zones 9 and 10, it’s much too late to plant your own. Here are the details on when to plant sweet pea seeds to get the most out of your plants.

When to Plant Sweet Pea Flower Seeds

Our first time seeing a massive display of sweet pea blooms was at Summers Past Farms in East County, San Diego. Their spectacular sweet pea maze is a favorite of kids and adults alike. In April, these blooms burst open and fill the air with their strong and intoxicating fragrance. We were instantly intrigued by how many plants can bloom so prolifically together. This experience is when we realized we did not truly understand how to grow sweet pea flowers. We were doing something wrong, but what?

Plant Sweet Pea Flowers in the Fall

After chatting with the owner, we learned that sweet pea seeds are best planted in the fall, allowed to grow and thrive through winter, giving blooms the next spring. After years of getting little to no blooms, we tried for ourselves, and what a difference it made! This little nugget of advice proved true for many flowers that benefit from a longer growing period through the fall and winter in Zones 9 and 10.

Why Plant Sweet Pea Flowers in the Fall?

Like many other flower seeds, sweet peas benefit from a fall planting as this gives them time to establish deep and resilient root zones during the cool, wet, and mild winters of Zones 9 and 10. As fall and winter go by, the plant may not look like it is doing much, but it is working hard to grow roots below ground that will suck up nutrients and create a longer and more vibrant display of blooms in the spring.

Sweet pea plants are unlikely to bloom during the shorter days of fall and winter as the days are too short. This makes the plant focus on vegetative growth. As soon as the days get longer in the spring, you will see the plant starting to bloom. In Zones 9 and 10, that could be as early as February. During particularly cool springs like the one we had here in 2023, we had sweet pea blooms until June!

Pro Tips for How to Grow Sweet Pea Flowers

We learned this great advice over a decade ago, and since then, we have had some of the most amazing, sweet pea bloom displays. What other pro tips should you know when growing sweet pea blooms in Zones 9 and 10?

• Soak seed for quicker germination.
• Plant on a drip line or irrigate daily to keep seeds moist. Seeds may take 7–14 days to germinate due to hard seed coating.
• Water only at soil level; sweet peas are prone to powdery mildew.
• Plant in full sun.
• A shot of blooming fertilizer will help increase the duration of spring blooms.
• Harvesting flowers often increases the bloom period.
• Plants will burn up when hot weather arrives (around June for San Diego’s inland county and May for East County).