Protecting Rhubarb from Frost, Summer Heat, and Dry Spells
Rhubarb’s reputation for toughness is well earned, but even this garden staple can falter under severe frost, scorching heat, or prolonged drought. Smart, seasonal protection means more reliable harvests, thicker stalks, and long-lived plants. Here’s how to shield your rhubarb from the elements in any climate.
1. Frost Protection for Rhubarb
Spring Frost
- Risks: Young, emerging stalks and buds are especially vulnerable to late spring frosts—frosted shoots turn mushy, black, or brittle.
- Prevention:
- Cover crowns at night with fleece, straw, or an upturned bucket during frost warnings.
- Remove covers by morning; don’t trap permanent moisture.
- Forcing Rhubarb? Always remove the forcing pot before a hard spell of late frost to avoid cooked crowns.
Autumn/Winter Frost
- Rhubarb crowns can withstand cold down to –20°C/–5°F, but extreme, prolonged cold or freeze/thaw cycles may cause rot.
- What to do:
- Mulch deeply with straw, leaf mold, or compost in late autumn; keep the mulch ring clear of the buds.
- Newly planted crowns are more at risk—mulch and/or cover with a thick blanket of leaves if temperatures plunge.
2. Summer Heat Protection
- Over 30°C/86°F? Rhubarb growth slows, stalks get thin or soft, and leaves wilt.
- Techniques:
- Mulch in spring with compost, straw, or bark to keep roots cool and moist.
- Shade new or container-grown plants with shade cloth or position where they get morning sun and afternoon shade.
- Water deeply in the cool of early morning or late evening.
- Signs of heat stress: Limp leaves that don’t recover by sunset, stalks that become hollow, or scorched leaf edges.
3. Drought and Dry Spells
- Though mature rhubarb can survive on neglect, dry spells can stunt new stalks, weaken plants, and reduce next year’s yield.
- Rules for drought:
- Water deeply, soaking the soil to the root zone every 7–10 days during dry weeks.
- Keep beds weed-free—less competition means more moisture for the rhubarb.
- In containers, water as soon as the top inch of soil dries.
4. What Not to Do
- Never let mulch smother the crown: Keep the central eyes exposed to avoid rot.
- Don’t waterlog: Avoid flooding beds or letting pots stand in trays of water.
5. Post-Stress Recovery
- Remove any mushy or burnt foliage—give the crown air and light.
- After a heatwave or drought, top-dress with compost and water in well.
- Lightly fork over compacted soil after a hard winter, and reset the crown if frost heave occurs.
Wrapping Up
With timely frost covers, summer shade, deep mulch, and respect for watering needs, your rhubarb will shrug off extremes and reward you with gorgeous, juicy stems year after year. Tough—but always grateful for a little gardener TLC!