How to Force Rhubarb for an Early, Sweeter Harvest

Feature	Indoor	Outdoor
Where	Shed or greenhouse	In the garden
Start Time	Late Jan–Feb	Feb–Mar
Needs	Pot, compost, full cover	Bin/bucket, mulch
Control	High	Medium
Harvest	3–4 weeks	4–6 weeks
Crown Use	Dug up, usually tossed	Left in place, recovers
Best For	Early crop, small spaces	Easy setup, no digging

What Does It Mean to Force Rhubarb?

Definition: Forcing rhubarb is a way to trick the plant into growing earlier by keeping it in the dark and giving it a bit of warmth. It skips the usual wait for warmer weather and encourages stalks to sprout sooner than they normally would.
Result: You end up with beautiful, pale pink stalks that are softer and much sweeter than the ones grown outdoors in full sun.

When Should You Start Forcing Rhubarb?

Best timing: Late January through early March is ideal. The plant needs a proper cold rest period—at least 7 to 8 weeks—to trigger dormancy.
Why it matters: That dormant stage is what prepares the crown for successful forcing.

Getting the Crown Ready

Crown age: Your rhubarb crown should be at least two or three years old before you attempt forcing.

For indoor forcing:

Dig up the crown in late fall.
Let it sit in the cold if it hasn’t gone dormant.
Store it in slightly damp compost if you’re not ready to force right away.

For outdoor forcing: Leave the crown in the ground and clean off any dead or decayed material before covering it up in early winter.

How Do You Want to Force It?

There are two ways to go about it—outdoor forcing or indoor forcing. Your method will depend on space, tools, and your personal preference.

Outdoor Forcing (aka the Classic Method)

Covering the crown: Use something tall and lightproof like a traditional rhubarb forcer, large bucket, or garbage bin. Make sure no light gets in.
Adding insulation: Wrap the base with compost, straw, or garden fleece to help trap in warmth.
Watching for growth: After a few weeks, stalks will start reaching toward the top of the container. Once they’re 8 to 10 inches long, it’s time to harvest.
Benefits: This method is simple, doesn’t disturb the plant, and works well in larger gardens.

Indoor Forcing (If You Want Full Control)

Setting it up:

1. Dig up a mature, dormant crown.
2. Place it in a large pot with moist compost or manure.
3. Move the pot into a warm, dark area like a greenhouse, cellar, or heated shed (ideally 50–60°F).
4. Cover it completely to block out all light.
5. Water occasionally to keep the soil damp but not soggy.

What to expect: In about 3–4 weeks, you’ll see stalks pushing through, ready for early harvest.
Advantages: You get full control over growing conditions and can enjoy an earlier harvest.

Looking After Your Rhubarb While Forcing

Keep it dark: Total darkness keeps the stalks pink and tender.
Don’t overwater: The soil should stay just damp. Overwatering can rot the crown.
Maintain warmth: Avoid big swings in temperature to prevent stressing the plant.

When and How to Harvest Forced Rhubarb

Harvest timing: Rhubarb is ready when the stalks are 8 to 10 inches long and have a rosy color.
How to harvest: Don’t cut the stalks. Instead, twist them gently and pull upward.
How much to harvest: Leave at least a third of the stalks behind so the plant isn’t overwhelmed.
What to avoid: The leaves are toxic—don’t eat them. Discard or compost them safely.

Helping the Plant Recover After Forcing

Indoor crowns: These are typically exhausted after forcing and should be composted.
Outdoor crowns: Let the plant rest and don’t harvest from it again that year. Feed it with compost or a balanced fertilizer to help it recover.
Important note: Don’t force the same crown two years in a row. Let it rest in between seasons.

Why Even Bother Forcing Rhubarb?

Better flavor: Forced rhubarb is less acidic and has a sweeter taste.
Improved texture: Stalks are softer and cook more evenly.
Earlier harvest: You’ll enjoy fresh rhubarb when most other plants are still dormant.

Common Forcing Mistakes and How to Avoid Them

Using immature plants: Always choose crowns that are at least two to three years old.
Letting in light: Even small amounts of light can green the stalks and ruin the texture.
Overwatering: Keep the compost damp—not soaked.
Replanting spent crowns: Indoor-forced crowns usually won’t recover. Compost them instead.

Conclusion

Forcing rhubarb is a clever way to bring a touch of spring to your table weeks ahead of schedule. With the right prep, care, and timing, you’ll be harvesting delicious stalks before your neighbors have even pulled out their gardening tools. Whether you choose the indoor or outdoor method, the results are absolutely worth the effort. Just remember to give your crowns a rest, harvest gently, and enjoy that sweet, early taste of the season.

Key Takeaway: Forcing rhubarb is all about giving the plant a little nudge during its dormancy so you can enjoy sweeter, more delicate stalks weeks before the outdoor crop is ready.

FAQs

Can I force rhubarb in a small patio pot?

Yes, you can. Just make sure the pot is big enough and you have a way to block out all light. A black bucket or heavy-duty fabric cover works well.

How do I know my rhubarb crown is mature enough?

Look for crowns that are two to three years old. Younger plants won’t have enough stored energy to handle forcing.

What should I do with the leaves after harvesting?

Rhubarb leaves are toxic, so they should be discarded or composted. Don’t use them in cooking or feed them to pets.

Can I freeze forced rhubarb?

Definitely. Chop it into pieces, place them in freezer bags, and freeze for use in pies, jams, and sauces later on.

Is it okay to force rhubarb every single year?

It’s better to give each crown a break between seasons. Forcing every year can weaken the plant over time.