Knowing the right time to plant potatoes in California is the first step to a fantastic harvest. The best planting times for this crop vary dramatically across the state’s unique climate zones. Get your timing right, and you’ll be rewarded with a bounty of homegrown spuds. Get it wrong, and you might face disappointing yields or pest problems.
California’s length and diverse geography create microclimates that directly impact your gardening calendar. What works in Eureka won’t work in El Centro. This guide breaks down the planting windows for Northern, Central, and Southern California. We’ll also cover how to choose varieties and the simple steps for planting and care.
When to Plant Potatoes in California – Best Planting Times for
Your location is the biggest factor in determining your potato planting schedule. Potatoes are a cool-season crop. They need cool soil to establish roots and develop tubers, and they prefer to mature before the peak summer heat arrives. Here’s the regional breakdown.
Northern California Planting Schedule
This region includes areas like the Sacramento Valley, the Bay Area, and points north. Winters are cooler and wetter, and summers are mild to hot.
* Coastal Areas (e.g., San Francisco, Eureka): You have a long, favorable window. Plant from late January through early April. The cool, foggy summers are ideal for potatoes, allowing for a extended growing season.
* Inland Valleys (e.g., Sacramento, Chico): Aim for a late winter to early spring planting. The perfect time is usually from mid-February to late March. You want the soil to be workable and past the danger of a hard frost, but you need to harvest before the intense valley heat of June and July.
Central California Planting Schedule
This encompasses the San Joaquin Valley and surrounding foothills. This area has hot, dry summers and mild, wet winters.
* Prime Planting Window: Your main planting time is in late winter. From early February through mid-March is generally ideal. The goal is to have potatoes in the ground so they can grow during the cool spring and be ready for harvest by early summer, before temperatures consistently soar above 90°F.
Southern California Planting Schedule
This region covers areas from San Luis Obispo down to San Diego and the inland deserts. Climates range from Mediterranean to arid.
* Coastal & Mild Inland (e.g., Los Angeles, San Diego): You have two distinct planting seasons! Your primary season is late winter (February to March). Your second, often overlooked season is in late summer for a fall harvest. Plant from late August to early September.
* Low Desert & Hot Inland Valleys (e.g., Palm Springs, Imperial Valley): Your growing season is reversed. Plant in the fall for a winter harvest. Get your seed potatoes in the ground from October to November. The mild winter temperatures are perfect for growth.
Key Factors Beyond Your Zone
While your region gives you the basic map, you need to check two local signals before planting.
* Soil Temperature: This is critical. Potatoes will rot in cold, soggy soil. Wait until the soil temperature at planting depth (4-6 inches) is at least 45°F (7°C). A soil thermometer is a cheap and invaluable tool. Ideally, aim for 50-55°F for best sprouting.
* Last Frost Date: While potatoes can handle a light frost after they emerge, a hard freeze can damage them. Planting 2-4 weeks before your area’s average last frost date is often a safe bet for getting a head start.
Choosing the Right Potato Variety for California
Selecting a variety suited to your season length is crucial. All potatoes fall into general categories based on how long they take to mature.
* Early Season (65-80 days): Great for areas with short springs that heat up fast. Plant these first.
* Examples: ‘Yukon Gold’, ‘Red Norland’, ‘French Fingerling’.
* Mid-Season (80-95 days): A reliable choice for most California gardens.
* Examples: ‘Kennebec’, ‘Purple Majesty’, ‘All Blue’.
* Late Season (95-130 days): Best for coastal areas with long, cool summers or for the fall planting window in Southern California.
* Examples: ‘Russet Burbank’, ‘German Butterball’.
Always buy certified disease-free seed potatoes from a garden center or reputable online seller. Don’t use potatoes from the grocery store, as they are often treated with sprout inhibitors.
How to Plant Potatoes in California Soil
Potatoes need loose, well-draining soil and full sun (at least 6-8 hours). Follow these steps for success.
1. Prepare the Soil: Loosen the soil to a depth of 12 inches. Mix in several inches of compost or aged manure. Potatoes prefer slightly acidic soil (pH 5.8-6.5). Avoid using fresh manure or too much nitrogen, which leads to leafy growth instead of tubers.
2. Chit Your Seed Potatoes: A few weeks before planting, place seed potatoes in a cool, bright spot to encourage short, sturdy sprouts. This gives them a head start.
3. Cut and Cure (Optional): Larger seed potatoes can be cut into pieces, each with 1-2 “eyes” or sprouts. Let the cut pieces air-dry for 1-2 days to form a callus, which prevents rot.
4. Plant: Dig a trench or individual holes about 6-8 inches deep. Place the seed potato piece with the eyes facing up. Space them 12 inches apart in rows spaced 2-3 feet apart.
5. Cover and Water: Cover with 4 inches of soil. Water thoroughly to settle the soil around the seed piece.
Caring for Your Growing Potatoes
Proper care after planting ensures a healthy crop.
* Hilling: This is the most important task. When green shoots reach about 6-8 inches tall, gently mound soil around the base, leaving the top few leaves exposed. Repeat this process every few weeks. Hilling protects developing tubers from sunlight (which turns them green and toxic), supports the plant, and increases yield.
* Watering: Keep soil consistently moist but not waterlogged. Even watering is especially crucial when the plants are flowering, as this is when tubers are forming. Reduce watering as the foliage starts to yellow and die back at the end of the season.
* Fertilizing: Use a balanced or low-nitrogen fertilizer at planting. A side dressing of a potassium-rich fertilizer (like potash) when hilling can benefit tuber development.
Harvesting Your California Potatoes
You can harvest “new” potatoes carefully about 2-3 weeks after the plants finish flowering. For mature, storage potatoes, wait until the plant foliage has completely yellowed and died back. Stop watering. Carefully dig around the plant with a garden fork, starting from the outside of the hill, to retreive your potatoes. Let them cure in a dark, dry, well-ventilated place for 1-2 weeks before storing.
Common Problems and Solutions in California
* Pests: Watch for potato beetles and aphids. Hand-pick beetles and spray aphids with water. Gophers can be a major issue; consider planting in raised beds or wire baskets.
* Diseases: Blight and scab are possible. Prevent blight by watering at the soil level (not overhead) and ensuring good air circulation. Scab is encouraged by alkaline soil; maintaining a lower pH can help.
* Green Tubers: This is caused by exposure to light. Always hill properly and store harvested potatoes in complete darkness.
FAQ: Planting Potatoes in California
Can I grow potatoes year-round in California?
In the very mildest coastal climates, you may have success with sequential plantings, but most areas have defined best windows. Potatoes generally do not thrive in peak summer heat or winter freeze.
What is the latest I can plant potatoes in California?
For most inland areas, planting after mid-April is risky due to heat. Coastal gardeners can sometimes plant into May. Southern California desert gardeners should stick to their fall schedule.
Can I plant potatoes from the store?
It’s not recommended. Store-bought potatoes are often treated to prevent sprouting and may carry disease that can infect your soil.
How often should you water potatoes in California’s dry climate?
Deep watering 1-2 times per week is usually sufficent, depending on your soil and temperature. The goal is even moisture, not soggy or bone-dry conditions.
Do potatoes need full sun?
Yes, they perform best with at least 6-8 hours of direct sunlight daily for strong growth and good yields.
By aligning your planting with your local California climate and following these simple steps, you’ll set the stage for a succesful and satisfying potato harvest. The perfect timing makes all the difference.