Wisconsin rhubarb growers know that early spring planting, as soon as the soil is workable, yields the best harvest. The best time to plant rhubarb in wisconsin is typically from late March through mid-May, depending on your specific region and the weather that year. You want to get those crowns in the ground while the plants are still dormant but the ground isn’t frozen solid.
Rhubarb is a cold-hardy perennial that thrives in Wisconsin’s climate. It actually needs a winter chill to produce well. So timing your planting right is key to getting years of delicious stalks.
Let’s break down exactly when and how to plant rhubarb across the Badger State. We’ll cover everything from soil temperature to regional differences.
Best Time To Plant Rhubarb In Wisconsin
The ideal window for planting rhubarb in Wisconsin is early spring, as soon as you can work the soil. This usually means when the ground thaws and isn’t too muddy. For most of the state, that’s between late March and early May.
You want the soil temperature to be around 40°F to 50°F. Rhubarb crowns are tough and can handle light frosts. In fact, a little cold helps them settle in.
Planting too late in spring can stress the plants. Hot summer weather isn’t great for newly planted rhubarb. It needs cool conditions to establish strong roots.
Regional Timing Differences Across Wisconsin
Wisconsin has varied climates. Southern Wisconsin warms up faster than the north. Here’s a quick breakdown:
- Southern Wisconsin (Madison, Milwaukee, Janesville): Late March to mid-April is prime time. Soil often becomes workable by early April.
- Central Wisconsin (Wausau, Stevens Point, Wisconsin Rapids): Aim for mid-April to early May. The ground stays frozen a bit longer here.
- Northern Wisconsin (Eau Claire, Green Bay, Rhinelander): Late April to mid-May is your window. Some years you might even push into late May if spring is cold.
Check your local frost dates. Rhubarb can be planted about 2-4 weeks before the last expected frost. That gives it a head start.
Why Early Spring Is The Best Time
Planting early gives rhubarb several advantages. The crowns are dormant, so they don’t suffer transplant shock as much. Cool soil encourages root growth before top growth begins.
Rhubarb needs a period of cold dormancy to produce well. Planting in spring lets it experience the natural cooling cycle the following winter. Fall planting is risky in Wisconsin because the ground freezes too early for roots to establish.
Early planting also means you might get a light harvest the following year. If you plant too late, you’ll wait an extra year for a full harvest.
Preparing Your Soil For Rhubarb
Good soil prep makes a big difference. Rhubarb likes rich, well-drained soil with a pH between 6.0 and 6.8. Test your soil before planting if you can.
Choose a sunny spot. Rhubarb needs at least 6 hours of direct sunlight daily. More sun means stronger plants and better stalks.
Steps To Prepare The Planting Area
- Clear the area of weeds and grass. Rhubarb doesn’t like competition.
- Dig a hole about 12 inches deep and 18 inches wide. This gives roots room to spread.
- Mix in plenty of compost or well-rotted manure. Rhubarb is a heavy feeder.
- Add a handful of balanced fertilizer like 10-10-10. Work it into the soil.
- If your soil is heavy clay, mix in some sand or peat moss to improve drainage.
Space plants about 3 to 4 feet apart. Rhubarb grows large and needs room. Crowded plants produce thinner stalks.
How To Plant Rhubarb Crowns
Planting rhubarb crowns is straightforward. You can buy crowns from nurseries or online. Bare-root crowns are common and work well.
Here’s the step-by-step process:
- Dig a hole deep enough so the crown sits about 2 inches below the soil surface.
- Place the crown in the hole with the buds facing upward. The roots should spread out naturally.
- Cover the crown with soil, but don’t pack it too tightly. Leave a slight depression around the plant to hold water.
- Water thoroughly after planting. This settles the soil and removes air pockets.
- Add a 2-inch layer of mulch around the plant. Straw, wood chips, or shredded leaves work well. Mulch keeps soil cool and moist.
Don’t plant too deep. If the crown is buried too far, it may rot. Two inches is the sweet spot.
Planting Rhubarb From Seed
You can also grow rhubarb from seed, but it takes longer. Seeds should be started indoors 8-10 weeks before your last frost date. Transplant seedlings outdoors after the danger of hard frost passes.
Seed-grown rhubarb may not be true to type. The stalks might vary in color and flavor. Most gardeners prefer crowns for consistency.
If you use seeds, plant them in pots with seed-starting mix. Keep them warm and moist. Harden off seedlings before moving them outside.
Caring For Newly Planted Rhubarb
After planting, your rhubarb needs consistent care. Water deeply once a week if there’s no rain. Rhubarb likes moist but not waterlogged soil.
Remove any flower stalks that appear in the first year. Flowering takes energy away from root and leaf growth. Just snap them off at the base.
Don’t harvest any stalks in the first year. Let the plant focus on establishing a strong root system. You can take a few stalks in the second year, but wait until the third year for a full harvest.
Fertilizing Your Rhubarb
Fertilize in early spring before growth starts. Use a balanced fertilizer like 10-10-10. Apply about 1/2 cup per plant, scattered around the base.
Side-dress with compost in mid-summer. This gives plants a boost during the growing season. Avoid high-nitrogen fertilizers, which can cause too much leaf growth and thin stalks.
Mulch again in fall after the first frost. This protects the crowns from winter heaving. In Wisconsin, freeze-thaw cycles can push plants out of the ground.
Common Problems With Rhubarb In Wisconsin
Rhubarb is generally trouble-free, but a few issues can arise. Here are the most common problems and how to handle them.
Pests And Diseases
- Rhubarb curculio: A small beetle that damages stalks. Handpick them off or use insecticidal soap.
- Crown rot: Caused by wet, poorly drained soil. Improve drainage and avoid overwatering.
- Leaf spot: Fungal disease that causes brown spots. Remove affected leaves and avoid overhead watering.
- Slugs: They chew holes in leaves. Use slug bait or diatomaceous earth around plants.
Most problems are preventable with good soil and proper spacing. Healthy plants resist pests better.
Bolting (Flowering)
Sometimes rhubarb sends up flower stalks, especially in hot weather. This is called bolting. It’s normal but reduces stalk quality.
Remove flower stalks as soon as you see them. Cut them at the base. This redirects energy back to the roots and leaves.
Some varieties are more prone to bolting. ‘Victoria’ and ‘Crimson Red’ are less likely to bolt than others.
Harvesting Rhubarb In Wisconsin
You can start harvesting in the second year after planting. Take only a few stalks, leaving at least half the plant intact. In the third year, you can harvest more heavily.
Harvest from late spring through early summer. Stalks are best when they’re 12-18 inches long and firm. Twist and pull them gently from the base, don’t cut them.
Stop harvesting by mid-July. This gives the plant time to store energy for next year. Continued harvesting into late summer weakens the plant.
Storing And Using Rhubarb
Fresh rhubarb keeps in the refrigerator for about a week. Wrap stalks in a damp paper towel and put them in a plastic bag. You can also freeze rhubarb for later use.
To freeze, wash and chop stalks into 1-inch pieces. Spread them on a baking sheet and freeze until solid. Then transfer to freezer bags. Frozen rhubarb works great in pies and sauces.
Remember that rhubarb leaves are toxic. They contain oxalic acid, which can cause illness. Always remove and discard leaves before using stalks.
Best Rhubarb Varieties For Wisconsin
Choosing the right variety helps ensure success. Some varieties are better suited to Wisconsin’s climate than others.
- Victoria: A classic green-stalked variety. It’s reliable and produces well in cold climates.
- Crimson Red: Red stalks with excellent flavor. It’s less prone to bolting and looks great.
- Canada Red: Deep red stalks that stay red when cooked. It’s very cold-hardy and productive.
- Valentine: A newer variety with bright red stalks. It’s disease-resistant and grows well in northern areas.
- Riverside Giant: Produces thick, green stalks. It’s a heavy yielder and tolerates heat well.
All these varieties handle Wisconsin winters fine. They need a cold period to break dormancy, which our state provides naturally.
Fall Planting Considerations
Some gardeners ask about fall planting. In Wisconsin, fall planting is risky. The ground freezes early, especially in the north. Roots don’t have enough time to establish before winter.
If you must plant in fall, do it in September. Mulch heavily after planting to insulate the soil. Even then, survival rates are lower than spring planting.
Spring planting is always the safer bet. You get better root establishment and higher survival rates. Stick with early spring for the best results.
Extending The Rhubarb Season
You can extend your rhubarb harvest with a few tricks. Forcing rhubarb produces tender, pink stalks earlier in spring. Cover crowns with a bucket or forcing pot in late winter. This blocks light and encourages early growth.
You can also plant multiple varieties with different maturity dates. Some ripen earlier, others later. This spreads out your harvest over several weeks.
Another method is to plant in a raised bed. Raised beds warm up faster in spring, allowing earlier planting. They also drain better, reducing rot risk.
Frequently Asked Questions
When is the best time to plant rhubarb in Wisconsin?
The best time is early spring, from late March to mid-May, as soon as the soil is workable. This gives crowns time to establish before summer heat.
Can I plant rhubarb in the fall in Wisconsin?
Fall planting is not recommended. The ground freezes too early for roots to establish. Spring planting is much more reliable.
How deep should I plant rhubarb crowns?
Plant crowns about 2 inches below the soil surface. Planting too deep can cause rot, while too shallow leaves roots exposed.
How long does rhubarb take to grow from planting to harvest?
You can take a few stalks in the second year, but wait until the third year for a full harvest. Patience pays off with stronger plants.
What is the best rhubarb variety for northern Wisconsin?
Canada Red and Crimson Red are excellent choices. They’re cold-hardy and produce well in northern climates.
Final Tips For Wisconsin Rhubarb Growers
Planting at the right time is just the start. Good soil, proper spacing, and regular care ensure a long-lived rhubarb patch. A well-maintained plant can produce for 10-15 years or more.
Don’t forget to divide your rhubarb every 5-7 years. Dig up the crown in early spring, cut it into sections with at least one bud each, and replant. This rejuvenates the plant and gives you more plants to share.
Rhubarb is a rewarding crop for Wisconsin gardeners. It’s low-maintenance, productive, and delicious. With the right timing and care, you’ll enjoy fresh rhubarb for years to come.
Remember to check your local extension office for specific advice. They have detailed info on soil conditions and frost dates for your area. Happy planting