Knowing when to plant sweet peas in California is the first step to a garden overflowing with color and fragrance. This simple timing choice makes all the difference between sparse vines and an abundent, long-lasting display.
Our state’s diverse climates mean there’s no single calendar date. But the rule is straightforward: sow seeds in the cool season. For most areas, fall planting is the secret to the strongest plants and earliest blooms. In colder inland valleys, a late winter sowing works perfectly. Let’s break down the optimal schedule for your specific region.
When to Plant Sweet Peas in California
This schedule prioritizes getting seeds into cool, moist soil. Sweet peas germinate best when soil temperatures are between 55°F and 65°F. They establish their roots over the cooler months, then explode with growth as days lengthen in spring.
Primary Planting Windows by Region
Coastal & Southern California (Zones 9-10): Plant from late October through December. This is the ideal window. The soil is still warm enough for germination, and seedlings have the entire cool season to grow strong before summer heat.
Northern California & Inland Valleys (Zones 8-9): Aim for February through early March. Wait for the soil to be workable and the worst frosts have passed. A late winter planting ensures they bloom before the summer heat peaks.
Mountain & Cold-Winter Areas (Zones 7-8): Sow seeds indoors in late winter (February) for transplanting after the last spring frost, or sow directly outdoors in early April. Protection from late frosts is key here.
Why Fall Planting is Often Best
Fall-sown sweet peas develop extensive root systems. They’re tougher and more resilient. When spring arrives, they’re ready to climb and flower much earlier, often by March or April. This extends your blooming season significantly. Plants also tend to be healthier, as they mature in cooler, more humid conditions that deter some pests.
Signs You’re Planting Too Late
- Soil feels warm to the touch.
- Daytime temperatures consistently above 75°F.
- Seeds germinate poorly or seedlings seem weak and stunted.
- Plants flower quickly but briefly before succumbing to heat.
Preparing for Planting
Sweet peas thrive in rich, well-draining soil. They are heavy feeders. A week or two before your planned planting date, prepare the ground.
- Choose a sunny location. They need at least 6 hours of sun, with afternoon shade beneficial in hot inland areas.
- Dig a trench or hole about 1 foot deep.
- Mix in generous amounts of compost or well-rotted manure. Add a balanced, slow-release organic fertilizer.
- Refill the trench partway with your improved soil, leaving room for seeds.
Seed Treatment for Better Germination
Sweet pea seeds have a hard coat. To speed up germination, you can nick the seed coat with a nail clipper (avoiding the eye) or soak seeds in room-temperature water for 4-8 hours before planting. This is especially helpful in cooler soil.
Step-by-Step Planting Guide
- Sow Seeds: Plant seeds 1 inch deep and 2-3 inches apart. If planting in rows, space rows about 6 inches apart.
- Water Gently: Water thoroughly after planting. Keep the soil consistently moist but not soggy until seedlings emerge, usually in 10-14 days.
- Provide Support Early: Install trellises, netting, or stakes at planting time. Disturbing roots later can set plants back. Sweet peas climb with tendrils and need something to grab onto.
- Thin Seedlings: Once seedlings are a few inches tall, thin them to 5-6 inches apart for good air circulation.
Caring for Your Sweet Peas
Consistent care keeps them flowering for months. Water deeply and regularly, especially once buds form. A layer of mulch helps retain soil moisture and keeps roots cool. Feed every 2-3 weeks with a liquid fertilizer high in potassium (like a tomato feed) to promote continuous flowering.
The most important task is harvesting. Pick blooms every day or two. The more you pick, the more the plant produces. If seed pods start to form, the plant thinks its job is done and will stop flowering. Regular cutting is your best tool for a long season.
Troubleshooting Common Problems
Poor Germination: Often caused by old seeds, hard seed coats, or soil that is too cold or too wet. Always use fresh seeds from a reputable source and pre-treat the coats.
Leggy, Weak Seedlings: Usually means not enough sunlight. Ensure they get full sun. Also, avoid over-fertilizing early on with high-nitrogen feeds, which promotes leafy growth over flowers.
Bud Drop or Lack of Flowers: Can be caused by sudden heat waves, inconsistent watering, or insufficient phosphorus in the soil. Ensure regular moisture and switch to a bloom-boosting fertilizer.
Powdery Mildew: A common fungal issue as temperatures warm. Prevent it by providing good air circulation, watering at the soil level (not overhead), and choosing resistant varieties. A weekly spray of a diluted milk solution can help prevent it’s spread.
Recommended Varieties for California
- Old Spice Mix: Extremely fragrant and heat-tolerant.
- ‘Cupani’: An original, highly fragrant bicolor (maroon and blue) variety.
- ‘Spencer’ Types: Large, frilly flowers on long stems, excellent for cutting.
- ‘Bijou’ Mix: A dwarf, bushy type perfect for containers or borders without support.
- ‘Royal Family’ Mix: Heat-resistant and long-stemmed, bred for California conditions.
FAQ
Can I plant sweet peas in spring in California?
Yes, but mainly in colder inland and mountain regions. In coastal and southern areas, spring planting leads to a short, disappointing bloom period before summer heat arrives.
What is the best month to plant sweet peas in Southern California?
November is often ideal. The soil is still warm from summer, but the air is cooling, creating perfect germination conditions.
Is it too late to plant sweet peas in January?
In coastal zones, January is still fine. In colder valleys, it’s better to wait until February or March for direct sowing, or start seeds indoors.
How do I get sweet peas to bloom longer?
Choose heat-tolerant varieties, provide afternoon shade, mulch heavily, water consistently, and pick flowers daily. Deadheading is absolutely essential.
Can sweet peas grow in pots?
Absolutely. Use a deep pot (at least 12 inches), provide a support structure, use high-quality potting mix, and water and fertilize more frequently than in-ground plants.
By following this regional timing guide, you give your sweet peas the best possible start. With their roots settled in cool soil, they’ll reward you with a spectacular, fragrant show that defines the California spring garden. Remember, a little patience in the fall or late winter leads to an abundance of beauty when the weather warms.