Grow Quality Rhubarb from Seed

Latin Name: Rheum rhabarbarum  

I have a rhubarb crown that has come from the original plant purchased by my Dad around 70 years ago. It produces a delicious crop of tender rhubarb stems from late spring. Growing beside it is an early seed grown variety. Rhubarb is a perennial plant with a rhizome. 

Growing rhubarb from seed is a slower process than planting crowns but is a very rewarding process. It is worth growing several plants and selecting the strongest plants to take to maturity.

Where can I plant rhubarb?

Rhubarb will grow well in most gardens but loves to be planted in a fertile, well manured soil in a warm spot. It is a hardy perennial which generally dies back over winter and then produces new leaves the following spring.

How to sow rhubarb seed?

It is very easy to start rhubarb from seed. It helps germination if you soak the seeds in warm water for a few hours but don’t worry if you have not got time. Sow the seeds in a good quality seed compost, placing them on the surface and cover with about 1 cm of compost. Ideally sow 1 or 2 seeds per pot.

What are the germination conditions for rhubarb seeds?

The seeds are not too fussy, so place them in a warm spot at about 15–20oC. After planting, spray the compost to make sure it is wet but not waterlogged. It will help germination if you cover the seeds with a mini greenhouse or clear plastic bag to retain moisture.

How long do rhubarb seeds take to germinate?

Germination is expected to take between 2 to 3 weeks depending on the temperature. When they have germinated remove the cover to allow good air to flow and avoid damping off.

When do I pot up the rhubarb seedlings?

There are no strict rules but if you leave them too long the seedling roots will grow into each other and the process of potting up will damage them. When the seedling have two leaves and are easy to handle and then pot into individual pots. Grow them on until they are ready to plant  in their final location.

Hardening off my rhubarb plants

It is important to harden off your rhubarb seedlings plants before planting them out. Move the plants from the greenhouse or windowsill initially to a sheltered spot outside. Keep an eye on the weather and if it gets cold then make sure you protect them at night. Allow a couple of weeks to fully harden off your plants. 

Where do I plant rhubarb into final position?

Select a fertile spot in the garden that gets some sunshine. It is important that the soil is prepared by adding loads of quality compost or well-rotted manure. Remember that your small plants will grow quite large when they are mature so transplant them about three feet apart.

How do I look after my rhubarb plants?

To help the plants establish, keep them well watered particularly during the first season. Later on when they are established there is a benefit in watering them during dry weather. Mulch the plants each year with compost or well-rotted manure which will not only feed the plants but retain moisture and suppress weeds. If the plant flowers then remove the flowers as they will reduce the leaf and root growth.

When can I start harvesting rhubarb leaves?

Don’t harvest any stems in the first year while the leaves establish. You can harvest a few stems in the second year and more in later years.  Rhubarb stems are the edible part of the plant. The leaves contain oxalic acid and should be removed and discarded.

I cover the plants early in the season to get some extra tender sweet rhubarb stems. This is known as ‘forcing’. By keeping them in the dark with a  bucket or rhubarb forcer, this encourages them to extend towards the light.

What varieties of rhubarb can I grow from seed?

There are two popular seed grown varieties. Rhubarb Victoria which is a heritage variety and Rhubarb Glaskins Perenial is a fast growing variety that gives a good crop from the second year.