Gadenin日本語Get the appThe shape of the year
Rhubarb is a hardy perennial with a genuine dormant period, and everything you do is timed against that cycle rather than against a calendar. The crown dies back completely in autumn, sits underground through winter accumulating the cold it needs, pushes hard in spring, and then spends the second half of the season rebuilding what the picking took out.
The single most important thing to understand is that the picking season is short and the recovery season is long. Roughly eight to ten weeks of pulling is followed by three or four months in which you take nothing at all and simply let the leaves work.
Because rhubarb needs several weeks below 40F (4C) to break dormancy properly, the timings below shift with your winters. In a mild area the spring flush comes early and the picking season starts sooner; in a cold one everything runs later but the crop is often stronger.
| Season | What the plant is doing | Your main job |
|---|---|---|
| Late autumn to midwinter | Dormant, accumulating cold | Clear dead leaves, mulch, plant or divide crowns |
| Late winter | Buds swelling below the surface | Cover a crown for forcing, protect early shoots |
| Early spring | Buds break and leaves unfurl | Nitrogen feed, slug watch, keep off the crown |
| Mid spring to midsummer | Full growth, main flush of stalks | Pull stalks, cut out flower spikes, water in dry spells |
| Midsummer to early autumn | Rebuilding root reserves | Stop picking entirely, water, keep weeds down |
| Mid to late autumn | Leaves yellow and collapse | Let it die back naturally, then clear and mulch |
Winter: the dormant season is the working season
Winter looks like nothing is happening, but almost every decision that shapes next year's crop is made now. This is the only time to plant a new crown or lift and divide an old one, because the plant can be dug up and cut into pieces without any leaves to support.
It is also when the main feed goes on. Once the dead foliage has been cleared away, spread a thick ring of well rotted manure or compost around each crown, keeping it clear of the buds themselves. Rain and worms take it down through the winter and the spring growth comes up through a fed soil.
If you intend to force a crown for early stalks, cover it in late winter before the buds move, and remember to rotate which crown you force so no plant is forced twice within two years.
Spring: growth, picking and vigilance
The first crinkled shoots push through as the soil warms. Feed with a nitrogen rich fertilizer as they appear, hoed in lightly rather than dug, since the feeding roots are near the surface. Watch for slugs, which do their real damage in these first two weeks while the shoots are soft and short.
Start pulling once the stalks are fully extended, generally twelve to eighteen inches (30 to 45 cm) with the leaf fully open. Take the outer stalks with a twist and a sideways pull, never a knife, and leave the small central shoots to come on. Never take more than half the stalks from a crown at one time.
Check the center of every crown weekly for a flower spike, which looks like a fat blunt bud in the middle. Cut it out at the base immediately; a spike left for a fortnight will be three feet (90 cm) tall and will have cost the plant a great deal.
- As the buds break Apply a nitrogen rich general fertilizer around the crown and hoe it in lightly. Refresh the mulch if it has thinned over winter, keeping it off the buds.
- Through the first flush Protect emerging shoots from slugs and from late frosts. Row cover over an early crown on a clear night avoids blackened, mushy stalks.
- Once stalks are full length Begin pulling. Twist and lean each outer stalk away from the crown until it releases, then trim off the toxic leaf blade outdoors and compost it.
- Every week Look into the middle of each crown for a flower spike and cut any you find right down at the base, leaving no hollow stub.
Summer and autumn: stop, feed, and let it die back
Around midsummer, roughly eight to ten weeks after you began, stop picking altogether. If the stalks are noticeably thinner than they were at the start, stop sooner. From this point every leaf on the plant is working for next spring, and the temptation to take a few more stalks is the most expensive mistake in growing rhubarb.
Keep watering through dry spells even though you are no longer picking, because the crown is building reserves and drought now shows up as a poor flush next year. A light second feed and a fresh mulch when you stop picking helps that rebuilding along.
In autumn let the leaves yellow and collapse on their own rather than cutting them green. When they have gone over, clear the dead foliage away from around the crown so slugs and rot have nowhere to overwinter, and put the winter mulch on. That closes the cycle and the crown goes back to sleep.
Do not tidy the crown by cutting green leaves off in late summer. Green foliage removed early is reserves removed early, and the plant pays for it in the following spring.
What to record each year
Four dates describe a rhubarb year completely: when the first bud broke, when you first pulled, when you last pulled, and when the leaves finally collapsed. Written down for two or three years running, they tell you far more about the health of a crown than any single observation ever could.
Add the position of each crown, its planting year, the year it was last divided, and whether you forced it. Division is due every five or six years and forcing needs a two year gap, and neither interval is something anyone remembers accurately without a note.
Finish each season with one line on how the stalks compared with last year: thicker, the same, or thinner. A crown that reads thinner two years running is asking to be lifted and divided in the coming dormant season, and that record is what tells you before the plant declines any further.