While rhubarb is often propagated from root divisions, growing rhubarb from seed is a much more economical method. Many commercial rhubarb plants available from nursery catalogs are just seedlings grown out for a year or two. If you’re patient, it’s easy enough to grow hundreds of rhubarb seedlings for the price of one nursery rhubarb plant.
Like many perennials, rhubarb doesn’t come true to seed. Apples are the same way, and while you can grow apples from seed, you never quite know what you’ll get. The seeds of any given plant will produce offspring won’t be the same as the parent, but that’s not always a bad thing. Every variety we know and love today was once a seedling, and it’s just been propagated ever since.
Unlike apples, which can be really different from their parents, rhubarb seedlings are only subtly different. For the most part, they’re quite similar, and only a true rhubarb connoisseur can really tell the difference most of the time.
Still, I was skeptical. I love my rhubarb, and I was pretty sure I’d know…until I learned one of our local commercial farms grows all their rhubarb from seed for their CSA and market sales. A friend of mine runs the farm, and she mentioned that they were going to add rhubarb to their spring CSA, and had just put in 1,000 plants.
I said, “Woah, that’s quite the investment!” Thinking they’d just dropped like $10k on rhubarb.
She answered, a bit confused, “Not really, about $10 in seed.”
I was impressed at the cost savings, but still skeptical. I forgot all about it, until about 3 years later when I stopped by her farmer’s market booth. Sure enough, there was a full stand of rhubarb. I had to know, so I bought some…and it was absolutely delicious.
That summer I saved my first rhubarb seed, and the following spring our rhubarb seedling empire began.
Saving Rhubarb Seed
The first step in growing rhubarb from seed, is saving the seed from your existing plants (or, just buying a packet). A single rhubarb plant produces literally hundreds of seeds, and when you buy them by the packet they’re about 10 cents per seed. Still a good deal, but a much better deal if you can just save seed.
Rhubarb plants send up a flower stalk in the early spring, and most gardeners break it off so that the plant puts more energy into producing stalks. Leave a few, on your best tasting rhubarb plants.
They look like this as they’re starting to unfurl…
Give them a bit more time, and that same flower stalk will open up into a profusion of beautiful tiny white blossoms. It’s really quite lovely, and the bees can’t get enough of them.
The blooms open in stages, and you’ll see some small green seed heads forming as the last blossoms are just opening.
It takes all summer, but by the fall, the rhubarb stalk will dry down. The dry, papery seed husks will start to catch the wind and blow away. That’s when it’s time to break off the whole stalk and collect the rhubarb seed.
The seeds come off the stalk relatively easily, and there’s plenty of them. I got about a quart of seed from a single stalk.
The important thing here is to make sure you allow the seed to dry completely before storing it. The papery husks hold the morning dew, and they can easily mold if stored immediately.
Set the rhubarb seed out on a tray and allow it to dry for a few days before packing it away until spring.
Growing Rhubarb from Seed
When I started doing research on growing rhubarb from seed, I assumed that the seeds would require a cold stratification period to germinate. Nope.
While the crowns require a cold winter period for dormancy to recharge, the seeds can be kept at room temperature all winter before planting.
Start rhubarb seeds indoors in pots or seedling trays about 8-10 weeks before the last frost. This is a few weeks before tomatoes, but a few weeks after asparagus grown from seed. Keep the seedlings moist, but not saturated. Rhubarb can die or be stunted from root rot in overly wet potting mix.
Rhubarb plants can handle a bit of frost, and they grow best transplanted a bit BEFORE the last spring frost. Harden plants off by taking them outdoors during the day and on warmer nights. About 2 weeks before the last spring frost, transplant the rhubarb seedlings to a permanent bed in the garden. Be sure that it’s well amended with a lot of compost and organic matter, and mulch them to suppress weeds and help keep the soil cool.
In warmer areas, choose a location where the rhubarb plants will be in shade during the heat of the day. Rhubarb plants grow best in cooler locations, and they’re generally considered hardy from zone 2 to 6.
Growing Rhubarb as an Annual in Hot Climates
Up here in the north in zone 4 Vermont, planting rhubarb is a long term commitment. They’re perfect for our harsh winters, and they pop out of the soil in the spring as soon as the snow melts.
The rest of my family lives in California, and my dad’s favorite thing in the world is strawberry rhubarb pie. While I can mail them rhubarb jam or strawberry rhubarb jam, it’s just not the same. My sister wants me to express mail her some fresh rhubarb stalks so she can try out my recipe for rhubarb custard pie as a surprise for him. While I’m happy to oblige, there’s going to be something else in that package…rhubarb seed.
I recently learned that rhubarb does well, even in zone 9-10 if planted in the late fall and grown as a winter annual. My sister lives in the Mojave desert, but I’m hoping conditions will be cool enough in the winter months to support rhubarb.
According to Southern Exposure Seed Exchange,
“To grow rhubarb as an annual in the fall and winter (zones 9 and higher), start the seeds in a cool location (a bright indoor spot or a shady outdoor place) from late August to early October. Transplant into the garden when the seedlings reach about 4 inches tall. The plants will be ready for harvest in March through early May. Intense summer heat will kill the plants, so harvest all the leaves in late spring. This technique only works where winters are very mild, or if you can protect the plants from damaging frost with a cold frame or row cover.”
Does it work? I hope so, but in any case, a single plant produces enough rhubarb seed to plant a whole field, so it won’t take much for me to mail off a bit of seed.