Best Time To Plant Rhubarb In California

Planting rhubarb in California requires working with the state’s varied microclimates, from coastal fog to inland heat. Knowing the best time to plant rhubarb in california is the first step to a successful harvest. This guide will walk you through exactly when and how to plant rhubarb in every region of California.

Rhubarb is a cool-season perennial that thrives in temperatures between 40°F and 75°F. In California, the timing shifts depending on where you live. Coastal areas have mild winters, while inland valleys get hot summers and cold winters. The key is to plant when the soil is cool but not frozen.

The absolute best time to plant rhubarb in California is in late fall or early winter, typically from November through January. This timing works for most of the state because rhubarb needs a cold period to break dormancy and produce strong stalks. In cooler mountain regions, you can plant as early as October. In warmer coastal zones, you can plant as late as February.

Planting in fall gives the roots time to establish before spring growth. If you miss the fall window, you can also plant in late winter or early spring, but the harvest will be smaller in the first year. Avoid planting in summer, as heat stress can kill young plants.

Coastal California Zones

In coastal areas like San Francisco, Los Angeles, and San Diego, the climate is mild year-round. Winter temperatures rarely drop below freezing. Here, the best time to plant rhubarb is from December to February. The cool, foggy conditions actually help rhubarb grow well. Plant in a spot that gets morning sun and afternoon shade to prevent bolting.

For coastal gardeners, you can also plant in early spring (March) if you missed the winter window. Just expect a lighter harvest in the first year. Water regularly, as coastal soil dries out faster in summer.

Inland Valley Zones

Inland valleys like the Central Valley, Sacramento, and Fresno have hot summers and cold winters. Here, plant rhubarb in November or December. The cold winter temperatures are perfect for triggering dormancy. Plant in a location that gets full sun in winter but partial shade in summer to protect from heat.

If you plant in late winter (January or February), make sure the soil is workable and not waterlogged. Inland soil can be heavy clay, so amend with compost to improve drainage. Rhubarb hates wet feet.

Mountain And High Desert Zones

In mountain areas like Lake Tahoe or the Sierra Nevada foothills, winters are harsh with freezing temperatures. Plant rhubarb in October or early November, before the ground freezes. You can also plant in early spring (March or April) after the last frost. The cold winters actually improve rhubarb flavor.

In high desert regions like the Mojave, plant in November or December. Protect young plants from wind and intense sun. Use mulch to keep soil cool and moist. Rhubarb can handle some cold, but extreme heat above 90°F will cause it to go dormant.

Southern California Specifics

Southern California has a unique challenge: mild winters and hot summers. The best time to plant rhubarb here is from December to February. Choose a variety that tolerates heat, like ‘Victoria’ or ‘Crimson Red’. Plant in a spot with afternoon shade to prevent stress. Water deeply but infrequently to encourage deep roots.

If you live in a coastal area of Southern California, you can also plant in early spring. But avoid planting in summer, as the heat will kill young plants. Rhubarb needs a cold period, so if your area rarely gets below 40°F, you may need to chill the crowns in the refrigerator for 4-6 weeks before planting.

How To Plant Rhubarb For Best Results

Planting rhubarb correctly is just as important as timing. Follow these steps for a healthy start:

Choose a sunny spot with well-draining soil. Rhubarb needs at least 6 hours of sun daily.
Test your soil pH. Rhubarb prefers a pH between 5.5 and 6.5. Add lime if soil is too acidic.
Dig a hole 12 inches deep and 18 inches wide. Mix in 2-3 inches of compost or aged manure.
Place the rhubarb crown so the buds are 1-2 inches below the soil surface. Space plants 3-4 feet apart.
Backfill with soil and water thoroughly. Add a 2-inch layer of mulch to retain moisture and suppress weeds.
Water weekly during the first growing season. Reduce watering in winter.

Rhubarb is a heavy feeder. Fertilize in early spring with a balanced 10-10-10 fertilizer. Apply again after harvest. Avoid high-nitrogen fertilizers, which can cause leaf growth at the expense of stalks.

Choosing The Right Rhubarb Variety

Not all rhubarb varieties grow well in California. Here are the best options for different regions:

Victoria: A classic variety that handles heat well. Good for inland valleys.
Crimson Red: Produces sweet, red stalks. Tolerates coastal fog and mild winters.
Canada Red: Cold-hardy and productive. Best for mountain zones.
Riverside Giant: A newer variety bred for warm climates. Works in Southern California.
Valentine: Early-season variety with bright red stalks. Good for coastal areas.

Buy crowns from a reputable nursery. Avoid seeds, as they take longer to establish and may not come true to type. Crowns should be firm with at least one healthy bud.

Preparing Soil For Rhubarb

Rhubarb is a long-lived plant that can produce for 10-15 years. Soil preparation is critical. Start by removing weeds and grass from the planting area. Dig in 3-4 inches of organic matter like compost or well-rotted manure. If your soil is clay, add sand or perlite to improve drainage.

For sandy soil, add more compost to retain moisture. Rhubarb needs consistent moisture but not waterlogging. Raised beds work well in heavy clay areas. Test your soil drainage by digging a hole and filling it with water. If it drains within 2 hours, you’re good.

If you’re planting in a container, choose a pot at least 18 inches deep and wide. Use a high-quality potting mix with added compost. Container plants need more frequent watering and fertilizing.

Caring For Rhubarb Throughout The Year

Once planted, rhubarb needs minimal care. But a few tasks will keep it productive:

Watering: Water deeply once a week during dry spells. In summer, increase to twice a week. Mulch helps retain moisture.
Weeding: Keep the area weed-free. Weeds compete for nutrients and water. Hand-pull weeds to avoid disturbing roots.
Fertilizing: Apply a balanced fertilizer in early spring and again after harvest. Side-dress with compost in fall.
Dividing: Divide plants every 4-5 years to maintain vigor. Do this in late fall or early winter when plants are dormant.
Removing flower stalks: Cut off any flower stalks that appear. Flowering reduces stalk production and quality.

In hot inland areas, provide afternoon shade during summer. You can use shade cloth or plant rhubarb near taller crops like corn or sunflowers. In coastal areas, watch for slugs and snails, which love rhubarb leaves. Use organic slug bait or hand-pick them at night.

When To Harvest Rhubarb

Harvest rhubarb in the second year after planting. In the first year, let the plant establish without harvesting. Starting in the second year, you can harvest stalks when they are 12-18 inches long. The best time to harvest is in spring and early summer, from April to June in most of California.

To harvest, grasp the stalk near the base and pull it gently. Twist slightly to detach it from the crown. Never cut stalks, as this can leave stubs that rot. Leave at least half the stalks on the plant to ensure it recovers. Stop harvesting by mid-summer to let the plant store energy for next year.

In coastal areas, you may get a second harvest in fall if the weather stays cool. But don’t push it. Rhubarb needs a rest period. If stalks become thin or spindly, stop harvesting and fertilize.

Common Rhubarb Problems In California

Rhubarb is generally pest-free, but a few issues can arise:

Crown rot: Caused by waterlogged soil. Improve drainage and avoid overwatering. Remove affected plants.
Leaf spot: Fungal disease that causes brown spots. Remove infected leaves and improve air circulation.
Slugs and snails: Common in coastal areas. Use barriers like copper tape or diatomaceous earth.
Bolting: When plants flower prematurely. Caused by heat stress. Provide shade and water consistently.
Poor growth: Often due to nutrient deficiency. Test soil and fertilize as needed.

If you see yellowing leaves, it may be a sign of overwatering or nitrogen deficiency. Adjust watering and apply a balanced fertilizer. Rhubarb leaves are toxic to humans and pets, so keep them out of reach.

Frequently Asked Questions

Can I plant rhubarb in summer in California?

It’s not recommended. Summer heat stresses young plants and can kill them. Stick to fall or winter planting for best results. If you must plant in summer, choose a heat-tolerant variety and provide shade.

How long does rhubarb take to grow in California?

From planting to first harvest, it takes about 1 year. In the second year, you can harvest for 4-6 weeks. Full production starts in the third year. Rhubarb is a slow starter but rewards patience.

Do I need to chill rhubarb crowns before planting?

In mild coastal areas where winter temperatures stay above 40°F, yes. Place crowns in the refrigerator for 4-6 weeks before planting. This mimics the cold period rhubarb needs to break dormancy. In inland and mountain areas, natural winter cold is enough.

What is the best rhubarb variety for Southern California?

Riverside Giant and Victoria are top choices. They handle heat better than other varieties. Plant in partial shade and water consistently. Avoid varieties like ‘Strawberry’ that need more cold.

Can rhubarb grow in containers in California?

Yes, but choose a large pot (at least 18 inches deep). Use a quality potting mix with compost. Water more frequently than in-ground plants. Fertilize monthly during the growing season. Container plants may need winter protection in cold areas.

Regional Planting Calendar For California

Here is a quick reference for when to plant rhubarb in different California regions:

Coastal North (Eureka, Fort Bragg): November to January
Coastal Central (San Francisco, Monterey): December to February
Coastal South (Los Angeles, San Diego): December to February
Inland Valleys (Sacramento, Fresno): November to December
Inland South (Bakersfield, Palm Springs): November to January
Mountain (Lake Tahoe, Big Bear): October to November, or March to April
High Desert (Mojave, Death Valley): November to December

Adjust by 2 weeks if you live in a microclimate. For example, coastal areas with more fog can plant later. Inland areas with early heat should plant earlier. Always check your local frost dates.

Tips For First-Year Rhubarb Care

The first year is critical for establishing a strong root system. Here’s what to do:

Do not harvest any stalks in the first year. Let all leaves grow to feed the roots.
Water deeply once a week. In hot weather, water twice a week.
Apply a 2-inch layer of mulch around the plant, but keep it away from the crown.
Remove any flower stalks immediately. They drain energy from root development.
Fertilize lightly in spring with a balanced fertilizer. Avoid high-nitrogen formulas.
Watch for pests and diseases. Treat promptly if needed.

By the second year, your rhubarb will be ready for a light harvest. Take only 3-4 stalks per plant in the first harvest. Increase to 6-8 stalks in subsequent years. A healthy plant can produce for 10-15 years with proper care.

Extending The Rhubarb Season

In California, you can extend the rhubarb season by using a few tricks:

Forcing: Cover crowns with a bucket or forcing pot in late winter. This produces tender, pink stalks 2-3 weeks earlier. Remove the cover after harvesting.
Succession planting: Plant crowns at 2-week intervals in fall. This spreads out the harvest window.
Shade cloth: In hot inland areas, use 30% shade cloth in summer to keep plants cool. This can delay dormancy.
Winter protection: In mountain zones, mulch heavily with straw or leaves to protect crowns from freezing.

Remember that rhubarb needs a dormant period. Don’t try to force it to grow year-round. A rest period of 6-8 weeks with temperatures below 40°F is ideal. In mild coastal areas, you may need to simulate this by withholding water in winter.

Companion Plants For Rhubarb

Rhubarb grows well with certain plants. Good companions include:

Beans: Fix nitrogen in the soil, which rhubarb needs.
Strawberries: They have similar water and sun needs.
Garlic and onions: Deter pests with their strong smell.
Brassicas (cabbage, kale): They don’t compete for nutrients.

Avoid planting rhubarb near:

Potatoes: They compete for nutrients and can spread diseases.
Cucumbers: They need more water and can cause root rot.
Sunflowers: They release chemicals that inhibit rhubarb growth.

Plant rhubarb at the edge of your garden bed so it doesn’t shade smaller plants. Give it plenty of space to spread. A mature plant can be 3-4 feet wide.

Harvesting And Storing Rhubarb

Harvest rhubarb in the morning when stalks are crisp. Use a gentle pulling motion to remove stalks. Trim off the leaves immediately, as they are toxic. Store stalks in the refrigerator in a plastic bag for up to 2 weeks. For longer storage, chop and freeze rhubarb. It freezes well without blanching.

Rhubarb can also be canned or made into jam. The tart flavor pairs well with strawberries, apples, and ginger. In California, rhubarb season runs from March to June in most areas. Coastal areas may have a longer season from February to July.

If you have excess rhubarb, share with neighbors or donate to local food banks. Rhubarb is a versatile ingredient in pies, crumbles, sauces, and even savory dishes. Just remember to never eat the leaves.

Final Thoughts On Planting Rhubarb In California

Planting rhubarb in California is rewarding if you get the timing right. The best time to plant rhubarb in california is from November to January for most regions. Coastal gardeners can plant through February, while mountain gardeners should plant in October or March. Choose a variety suited to your climate, prepare the soil well, and be patient in the first year.

With proper care, your rhubarb will produce for a decade or more. Enjoy the tart stalks in spring and summer, and don’t forget to divide plants every few years to keep them vigorous. Happy planting!