Can I Harvest Rhubarb in September?

Rhubarb is a cold-hardy perennial vegetable that produces tart stalks used to make pies jams chutneys and other treats. While rhubarb is typically harvested in spring and early summer, many gardeners wonder if they can extend the harvest into September and even October. Here’s what you need to know about harvesting rhubarb in the fall.

Overview of Rhubarb

Before jumping into fall harvesting, let’s do a quick rhubarb refresher. Rhubarb plants produce thick stalks from a central crown. The leaves are toxic due to high levels of oxalic acid and should not be eaten. There are two main types of rhubarb:

• Field or garden rhubarb Grown outside in zones 3-8 Requires a winter dormancy period

• Hothouse or forced rhubarb: Grown in heated greenhouses to produce stalks earlier. Does not require dormancy.

Popular garden varieties include Victoria, Valentine and Crimson Red. Rhubarb is easy to grow in most regions, producing harvestable stalks 2-3 years after planting crowns. It prefers full sun and fertile, well-drained soil amended with compost or manure.

Spring and Summer Harvesting

The ideal time to harvest rhubarb is in spring when the stalks are young and tender. In cold regions, harvest begins in April-May. In warmer areas, you can start earlier in March-April. Harvest lasts 8-10 weeks.

To harvest rhubarb:

• Grip the stalk at the base and pull up twisting slightly. Use a sharp knife to cut the stalk off at ground level.

• Take no more than 1/3 of the stalks from each plant at a time. Leave at least 3 large leaves on each plant.

• Stalks should be 10-15 inches long and 1⁄2 to 1 inch thick.

• Pull stalks gently to avoid damaging the crowns.

Stop harvesting by midsummer to allow the plants time to recover before going dormant. Take the last stalks by early July in the North and late June in the South.

Can You Harvest in Fall?

Gardeners are often eager to get a few more rhubarb stalks in September and October before frost hits. The short answer is yes, you can extend the rhubarb harvest into the fall but proceed with caution. Here are a few guidelines:

Only Harvest Lightly

Resist the temptation to harvest heavily in the fall. Rhubarb plants are preparing for dormancy and need time to recover and store energy. Take no more than 1-2 stalks per plant, and never harvest more than 25% of the total stalks.

Check Plant Health

Before harvesting, assess the overall vigor of your plants. If the rhubarb bed produced well this year and plants appear robust with plenty of stalks and leaves, go ahead and take a few. But if plants are small or stressed from summer heat, do not harvest at all. Let them focus on overwintering.

Monitor Oxalic Acid

Oxalic acid levels do rise in rhubarb stalks after midsummer as the leaves start to die back. You are unlikely to consume toxic quantities from fall rhubarb, but some find stalks increasingly bitter and stringy. If you don’t enjoy the taste or texture, it’s fine to end the harvest season earlier.

Stop Harvest Before Frost

End all harvest at least 2-4 weeks before your average first fall frost date. This gives plants a chance to go fully dormant. Any stalks remaining after frost are inedible.

Caring for Rhubarb in Fall

Rhubarb needs a little late season and winter care to produce well next year:

• Weed carefully around plants, being careful not to damage the shallow roots. Apply winter mulch after ground freezes.

• Fertilize with compost or manure in early fall. This stimulates crown growth.

• Remove flower stalks as they appear to prevent the plant from going to seed.

• Divide older crowns every 5-8 years in early spring to rejuvenate.

• Remove damaged leaves or debris. Leave intact leaves in place all winter.

• Add extra mulch in very cold regions for insulation.

• Water during drought periods in fall until ground freezes.

With proper care, your rhubarb will be healthy and ready for next year’s harvest!

Storing and Preserving Fall Rhubarb

While you may only get a small fall rhubarb harvest, there are ways to extend enjoyment of those tart red stalks:

• Freeze chopped pieces in airtight containers to use in baking. Freezing retains texture and flavor better than canning.

• Make jams or chutneys. The high sugar and acidity allows for safe canning and storage at room temperature.

• Dehydrate thinly sliced pieces to use in pies or snacks.

• Pickle tender stalks in brine for a unique flavor.

• Use in baked goods like muffins and cakes and store the finished items in the freezer.

What About Forced Rhubarb in Winter?

Forced rhubarb is harvested November through March from heated greenhouses that manipulate temperature and light to stimulate growth. Forced rhubarb grows quickly and has notably thinner, milder stalks than field-grown. It also requires intensive greenhouse production techniques.

For home gardeners, the more practical option is to enjoy field-grown rhubarb seasonally, and rely on preserved or purchased rhubarb in winter. With proper fall care, your plants will bounce back vigorously in spring!

Frequently Asked Questions About Fall Rhubarb

Is Fall Rhubarb Poisonous?

Rhubarb stalks become more bitter and stringy after midsummer, but are not poisonous or unsafe to eat. Toxic oxalic acid accumulates in the leaves, not the stalks. Simply remove all leaves before eating rhubarb at any time of year.

Can Frost Damage Rhubarb?

Once temperatures drop below 25°F (-4°C), stalks and leaves are damaged by frost. However, the roots and crown will survive freezing as long as properly mulched. Snow cover also provides insulation.

How Long Does Rhubarb Last in the Garden?

Rhubarb plants can produce for 10-15 years or longer. Harvests decrease as crowns age and weaken. Rejuvenate old plants by dividing crowns every 5-8 years in early spring.

What Type of Soil Does Rhubarb Need?

Rhubarb thrives in deeply cultivated, fertile soil amended with lots of organic matter. Well-drained loam is ideal. Raised beds enriched with compost or manure will support vigorous growth.

When Should I Divide and Transplant Rhubarb?

The best time to divide rhubarb crowns is in early spring just as the plants begin growing. Dividing in fall is also possible but can stress plants going into winter.

Conclusion

With proper judgment, gardeners can enjoy a small bonus harvest of tart rhubarb stalks in September and October. Just be careful not to overharvest during this cooldown period. The majority of the year’s harvest still occurs in spring and early summer when stalks are most tender. Provide good fall care, and your rhubarb will take off again next season.