When To Plant Sweet Peas In Southern California

If you’re a gardener in Southern California, knowing when to plant sweet peas is the key to a spectacular bloom. The optimal timing for planting sweet peas in Southern California is a bit different than in colder climates, but getting it right means months of fragrant, colorful flowers.

Our coastal and inland valleys have a unique climate that lets us grow sweet peas during the cooler seasons. Planting at the correct time ensures strong roots and a long flowering period before the summer heat arrives. Let’s look at how to schedule your planting for the best results.

For most of Southern California, the prime planting window is from late fall through early winter. Aim to get your seeds in the ground between mid-October and late December. This timing is crucial because sweet peas thrive in cool conditions.

Planting in fall allows the seeds to establish a robust root system during the cooler, wetter months. The plants then put on vigorous growth as days begin to lengthen in late winter, leading to a bloom season that can start as early as February and last into May.

Why Fall and Winter Planting Works Best

Sweet peas are cool-season annuals. They germinate best in soil that is between 55°F and 65°F. Hot soil prevents germination. Our Southern California fall and winter soils are perfect for this.

The plants grow best with daytime temperatures in the 60s and 70s. They can handle mild frosts, which makes them ideal for our winters. If you wait until spring to plant, the plants will struggle to establish before the heat causes them to wilt and stop flowering.

Microclimate Adjustments

Your specific location in Southern California will fine-tune your planting date.

Coastal Areas (Los Angeles, San Diego, Orange County): You have the longest, most flexible window. Planting from October through January is generally successful. The ocean influence keeps temperatures moderate.
Inland Valleys (San Fernando, San Gabriel, Riverside): Target October to November. These areas get hotter faster in spring, so an earlier start is beneficial. A light frost is more possible but rarely harms established seedlings.
Desert Areas (Palm Springs, Low Desert): Planting is trickier. Aim for a very late fall planting in November or even early December. You may need to provide afternoon shade as spring temperatures rise quickly.

Preparing Your Soil for Success

Sweet peas prefer rich, well-draining soil. They are moderate feeders but will reward you for good preparation. Here’s how to get your bed ready:

Choose a Sunny Spot: Select a location that gets full sun, at least 6 hours a day. In hotter inland areas, a spot with morning sun and afternoon shade can prolong blooming.
Amend the Soil: Work the soil to a depth of about 12 inches. Mix in a generous 3- to 4-inch layer of compost or well-rotted manure. This improves drainage and provides nutrients.
Check Drainage: Ensure the area doesn’t puddle after watering. Raised beds are an excellent option if your soil is heavy clay.
Hold Off on Fertilizer: Avoid high-nitrogen fertilizers at planting. They encourage leafy growth at the expense of flowers. A balanced, slow-release organic fertilizer is fine if your soil is poor.

A Note on Seed Treatment

Sweet pea seeds have a hard coat. To speed up germination, you can soak them in room-temperature water for 12-24 hours before planting. Alternatively, you can nick the seed coat with a file or nail clipper. This step isn’t always necessary, but it helps, especially if you’re planting later in the window.

Step-by-Step Planting Guide

Sow Seeds Directly: Sweet peas don’t like their roots disturbed, so direct sowing is best. Plant seeds about 1 inch deep and 2-3 inches apart.
Water Gently: After planting, water the area thoroughly. Keep the soil consistently moist but not soggy until seedlings emerge, which usually takes 10-14 days.
Provide Support Early: Install your trellis, netting, or stakes at planting time. This avoids damaging young roots later. Sweet peas can climb 6 to 8 feet!
Thin Seedlings: Once seedlings are a few inches tall, thin them to about 6 inches apart to allow for good air circulation.

Caring for Your Growing Sweet Peas

Consistent care through the growing season leads to more flowers.

Watering: Water deeply once or twice a week, depending on rainfall. The goal is even moisture. Drip irrigation or a soaker hose is ideal to keep foliage dry and prevent disease.
Mulching: Apply a 2-inch layer of organic mulch around the base of the plants. This keeps the roots cool, conserves water, and suppresses weeds.
Feeding: When plants begin to bud, feed them with a fertilizer higher in potassium (the third number on the label). A tomato or bloom booster fertilizer applied monthly works well.
Deadheading: This is the most important task for prolonged blooming. Pick flowers often for bouquets, and regularly remove any faded or developing seed pods. If the plant sets seed, it will think its job is done and stop flowering.

Common Pests and Problems

Southern California gardens have a few specific issues to watch for.

Aphids: These are common. Blast them off with a strong jet of water from your hose or use insecticidal soap.
Powdery Mildew: This fungal disease appears as white powder on leaves, especially as weather warms. Prevent it by watering at the soil level, ensuring good spacing for air flow, and choosing resistant varieties.
Birds & Slugs: Birds sometimes pull up seedlings. Use netting if needed. Slugs can be a problem in damp, coastal areas; use organic slug bait if necessary.

Extending the Bloom Season

To get the absolute longest show of flowers, try these two tips:

Succession Planting: Sow a second batch of seeds in November or early December, about a month after your first planting. This can stagger the bloom time.
Keep Them Cool: Mulch heavily and never let the soil dry out completely. As temperatures rise in late spring, providing some afternoon shade with a shade cloth can add extra weeks to your harvest.

Recommended Varieties for SoCal

Some sweet pea varieties perform exceptionally well in our region. Look for heat-tolerant and mildew-resistant types.

Old Spice Mix: Known for its incredible fragrance and heat tolerance.
Cupani: An heirloom variety with beautiful bicolor flowers and strong scent.
Spencer Types: Offer large, frilly flowers in a huge range of colors. Many modern Spencer types have improved mildew resistance.
Mammoth Series: A robust, tall-growing series that’s reliable and floriferous.

FAQ

Can I plant sweet peas in spring in Southern California?

It’s not ideal. Spring-planted sweet peas will have a very short bloom period before succumbing to the heat. For the best results, always aim for a fall or early winter planting.

What if I missed the fall planting window?

You can try planting in very early January, but be prepared for a shorter season. You might also look for started seedlings at local nurseries in late fall, which gives you a head start.

How often should I water sweet peas?

Water deeply when the top inch of soil feels dry. This might be once a week in cool winter weather and twice or more as temperatures increase in spring. Consistent moisture is key.

Why are my sweet peas not flowering?

Several factors can cause this: too much nitrogen fertilizer, not enough sun, inconsistent watering, or not deadheading. Also, if the plants experience sustained temperatures above 80°F, they will often stop setting buds.

Can I grow sweet peas in containers?

Absolutely. Choose a deep pot (at least 12 inches) and provide a sturdy support. Use a high-quality potting mix and be vigilant about watering, as containers dry out faster. A dwarf or bush-type variety is a good choice for pots.

Getting the timing right is the first and most important step. By planting your sweet peas in the cool season, you give them the foundation they need for a spectacular display. With a little preparation and consistent care, you’ll be rewarded with an abundance of beautiful, fragrant blooms that are perfect for cutting and bringing indoors. There’s nothing quite like a bouquet of homegrown sweet peas from your own garden.