Rhubarb is a tasty spring vegetable that many home gardeners grow for its tart and stringy stalks, which are great for making pies, jams, and compotes. But have you ever wondered what the seeds of this common garden plant look like?
In this article, we’ll take an in-depth look at rhubarb seeds – their appearance how they form how to harvest them, and tips for growing rhubarb from seed. Whether you’re an experienced gardener or just starting out, read on to learn all about this versatile plant’s seeds.
An Overview of Rhubarb Seeds
Rhubarb seeds are tiny round or oval-shaped and light brown in color. They have a rough, pebbly texture and measure 1 to 2 mm wide when fully mature. The seeds develop inside thin, papery seed pods that grow upward from the rhubarb plant on tall, slender flower stalks. Each seed pod contains dozens of tiny rhubarb seeds.
While the leaves of rhubarb plants are toxic, the seeds are perfectly safe to handle and consume. However, most people don’t eat them – rhubarb seeds are collected mainly for propagating new plants.
How Rhubarb Seed Pods Form
In the second or third year after planting, rhubarb plants will send up flower stalks topped with small, clustered flowers. This usually happens in early spring. The pretty white or greenish-white blooms later develop into the papery seed pods.
It takes the entire growing season for the seed pods to mature. By late summer or early fall, they will dry out completely, turn light brown, and split open to release the seeds. This is the signal that the seeds are ripe and ready to harvest.
Harvesting Rhubarb Seeds
The ideal time to collect rhubarb seeds is after the seed pods have dried out and opened but before the seeds start blowing away in the wind. To harvest them, simply cut off the flower stalks once the pods turn brown.
Place the stalks in a paper bag and allow them to finish drying indoors for a week or two. When ready, you can easily rub or shake the brittle pods to separate the seeds. Pick out any remaining plant debris.
Store the dry seeds in an airtight container in a cool, dry spot. Kept this way, they’ll remain viable for up to 3 years. Each flower stalk produces dozens of seeds – you’ll have plenty to save some for planting!
What Do Rhubarb Seeds Look Like When They Sprout?
Rhubarb seeds don’t require any special treatment before planting. In the right conditions, they’ll germinate in 1-2 weeks.
Sprouted rhubarb seeds have two small green oval seed leaves (cotyledons). The first true leaves are spade-shaped with a hint of rhubarb’s characteristic ruffled edges. They emerge a few weeks after germination.
Seedlings started indoors are ready to transplant outside after 8-10 weeks when the plants reach 3-4 inches tall.
Tips for Growing Rhubarb from Seed
While rhubarb crowns offer quicker harvests, growing from seed is a simple, affordable option for establishing a patch. Here are some tips:
-
Start seeds indoors 8-10 weeks before your last expected spring frost.
-
Use deep pots and a light seed starting mix. Plant 1-2 seeds per pot, 1/4 inch deep.
-
Keep soil moist but not soaked. Move sprouted seedlings to bright, indirect light.
-
Harden off young plants before transplanting them outside in early spring after danger of hard frost has passed.
-
Prepare garden beds with compost and mulch to retain moisture. Space plants 2-3 feet apart.
-
Water plants regularly if rainfall is lacking, especially in the first year.
-
Allow plants to establish for 2-3 years before taking any stalks.
-
Remove flower stalks to promote better leaf and stalk growth.
With proper care, in 3-4 years you can expect to harvest abundant, tasty rhubarb stalks from your grown-from-seed plants!
Fun Facts About Rhubarb Seeds
Beyond their function as propagating material, rhubarb seeds have some interesting quirks:
-
Rhubarb stalk color and taste is not always identical to the parent plant when grown from seed.
-
The seeds contain oxalic acid, giving them a tart, lemony flavor if eaten.
-
Rhubarb seeds may require exposure to cold temperatures in order to germinate well.
-
Seedling rhubarb plants exhibit stronger hybrid vigor than crowns.
-
Each rhubarb flower stalk can produce 100-1000 or more seeds!
Frequently Asked Questions About Rhubarb Seeds
How can you tell when rhubarb seeds are ripe and ready to harvest?
Rhubarb seeds are ready to harvest when the seed pods on the flower stalks turn completely brown and dry out until they are brittle. Gently shaking the stalks and listening for the rattle of seeds inside is a good indication they are ready. The pods will split open and release the mature seeds if not cut first.
What is the best way to extract rhubarb seeds from the seed pods?
After harvesting and fully drying the flower stalks, you can rub them between your hands over a bowl or container to separate and collect the seeds. Avoid crushing the pods, just gently rub to release the seeds. You can also place the entire stalk in a bag and shake or crush lightly. Then pick out the debris and pour off the seeds.
How long do rhubarb seeds stay viable after harvesting?
Rhubarb seeds can remain viable for 2-3 years if stored properly in a cool, dark place in an airtight container. For best germination rates, it’s ideal to plant them within 1-2 years. Older seeds may still sprout but will have lower germination.
Is cold stratification required for rhubarb seeds to germinate?
No, cold treatment is not required prior to planting rhubarb seeds, but some gardeners say exposing them to cold temps improves germination. They can be directly sown in spring or started indoors without any special pre-treatment. Just follow the usual planting directions.
How can you boost germination rates for rhubarb seeds?
Giving rhubarb seeds a good start by sowing them shallowly in warm, moist nutrient-rich soil, keeping the temperature around 70°F, and providing plenty of light will help boost germination rates. Prior cold exposure may also increase viability. Check seeds often and keep them evenly moist.
How to Collect Rhubarb Seeds
You could always obtain rhubarb plant seeds from your local seed supplier but saving rhubarb seedpods from your garden is much more gratifying. However, you may or may not have the opportunity to harvest your own seeds because your rhubarb may not flower in any given year. The probability of flowering, or bolting in rhubarb, increases with certain varieties, the age of the plant, and the presence of certain environmental conditions and stressors such as heat and drought. Keep a close watch on the base of your rhubarb plant for the formation of tightly packed flower pods which, if left to fruition, will emerge into long stalks with unfurled flowers at the top. These flower pods can form at any point during the rhubarb growing season and can appear even in the early spring. Rhubarb can be grown as a strictly ornamental plant and, after setting your eyes on the flower display, it’s easy to see why. You may at this point be tempted to cut the flower stalks prematurely and incorporate them into a flower bouquet, however, you will miss your opportunity for rhubarb seed collection. Patience is a virtue here, as you will need to wait for a transformation to take place after the rhubarb has flowered before you harvest your rhubarb plant seeds. The flowers will turn into green seed and then eventually these seeds and the entire rhubarb branch (as a whole) will dry out and turn brown. This is when to harvest seeds from rhubarb. Saving rhubarb seedpods is easy. Clip the stalks with snips or break the brittle branches off by hand. Hover the branches over a cookie sheet and run your fingers down the stalk, brushing the seeds onto the cookie sheet. Dry the seeds on the cookie sheet for a week or two, then package them up and put in a dark, cool place for storage. It has been said that the shelf life of harvested rhubarb plant seeds does not extend past the second year, so this is something to keep in mind when planning your garden.