Rhubarb

What summer picnic would be complete without the tang of rhubarb pie? 

While purists may enjoy their rhubarb raw, dipped lightly in sugar, many of us prefer rhubarb pie with luscious strawberries. However you eat rhubarb, it is a sturdy perennial that can provide shape, color, and food in a garden or landscape for decades. These plants can get pretty big, making rhubarb excellent anchor plants in a foodscape.

Rhubarb

Rhubarb (Rheum rhabarbarum) is generally a cool season plant. It needs temperatures below 40ºF in the winter and prefers temperatures below 75ºF in the summer. That being said, I have had excellent success with rhubarb in San Jose (CA) where our peak summer heat can reach above 100°F.

You may be surprised to learn that rhubarb is related to buckwheat. If you look at the seeds, you can see the similarity. Rhubarb is believed to have started in Asia, some 5,000 years ago. Marco Polo is cited as the one who brought it to Europe and Benjamin Franklin carried rhubarb to North America, way back in the 1700s!

Green rhubarb seeds

Dried buckwheat seeds (Mariluna) CC BY-SA 3.0

How to grow rhubarb

When selecting a site for rhubarb, keep the plant’s mature size in mind. Rhubarb plants can reach 3’ in height and 4’ in diameter. Rhubarb generally prefers full sunlight, but mine are under a small apricot tree (which probably protects the rhubarb from our summer heat). In temperate regions, the rhubarb harvest begins in April and continues until September.

Individual plants will be productive for 8-20 years, but, since they grow from rhizomes, the plants will replace themselves over time. [Side note: my mother purchased a 200-year old farm house in Upstate New York many years ago and decided to plant rhubarb along the southern side of an outbuilding. Apparently, the original owners felt the same way because, come spring, not only did the new plants come up, but so did the offspring of the original plants! Needless to say, Mom had plenty of rhubarb!]

Rhubarb can be grown in large containers, as long as there is enough room for a season’s growth. Rhubarb will do much better in the ground. Follow these steps to get your rhubarb patch started:

• Select a site large enough for the plants, where they will get plenty of sunlight.
• Clear all weeds from the area.
• Top dress the bed with aged compost, since rhubarb prefers nutrient rich, well-drained soil.
• In early spring (or fall), dig a large hole for each plant, spacing plants 4’ apart.
• Plant one-year rhubarb crowns 2-3” below the soil surface and cover with aged compost or manure, before bud or leaf growth is visible.
• Mulch with straw or aged compost and water well. Rhubarb plants are heavy feeders and will need repeated applications of compost throughout the year.
• Do not apply chemical fertilizers to rhubarb in the first year. Chemical nitrates can kill young rhubarb plants. Mature plants can be fed one cup of 10-10-10 fertilizer each spring.
• Be sure water regularly during summer to prevent bolting.
• If flower stalks do appear, remove them. Flowering and going to seed will use up nutrients better spent producing roots and edible stalks. Also, rhubarb grown from seed is often not as tasty as plants grown from crowns.
• Mature plants should be dug up, separated, and replanted every 3-4 years while they are dormant (early spring or fall).
• Be alert for crown rot, the only real problem for rhubarb. Most insects do not bother rhubarb, probably due to the oxalic acid* in the leaves.
• Do not harvest rhubarb stalks the first year. This gives the root system time to get established.
• After the harvest has ended, remove any dead plant material and cover the plants with 2-4” of mulch. Underneath this protective cover, the plants will rest and prepare for the next growth season.

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*While rhubarb leaves are mildly toxic, they are not the poison we have been led to believe. You would have to eat several pounds of rhubarb leaves to cause problems. In fact, spinach has more oxalic acid than rhubarb. That being said, I do not feed them to my chickens.

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One easy way to keep weeds down in a rhubarb patch is to simply take a few of the large rhubarb leaves and lay them on the ground. The leaves block sunlight needed by the weeds and then they break down, adding organic matter to the soil.

Get your rhubarb crowns in today for a lifetime of red-stalked deliciousness!