Rhubarb – the pie plant

Rhubarb – most folks consider rhubarb to be a spring delicacy. When driving through town or the country, you will probably notice most gardens contain a clump of rhubarb. But whether you love it or hate it, during this time of year, the tart and tangy rhubarb is at its flavor peak.

Although the rhubarb that grandma grew is not as sweet as the newer, red-stalked types, like Canada Red or Valentine, it still will make some mighty fine pies. Area greenhouses and nurseries have rhubarb plants available for planting now, but remember to wait 3 years before harvesting, to allow plant crown and roots to become established. Rhubarb plants prefer a well drained, sunny location with good air circulation.

Once established, rhubarb “grows like a weed” and requires little additional care. Rhubarb plants are heavy feeders, and soil fertility levels can become low. Early spring was the best time to apply fertilizer, such as 10-10-10, but now is a good time to apply compost around the base of rhubarb plants. Mulching with compost will help to retain moisture, keep weeds down, and improve the soil structure.

Harvest rhubarb when stalks, which are actually called petioles, are well-developed and about 10 inches long. To keep rhubarb healthy, vigorous and producing well, do not remove more than one-half of the stalks at a time when harvesting. Make your final rhubarb harvest for the year by the end of June, as additional harvesting can deplete plant energy reserves, resulting in less production next year.

Older rhubarb clumps can become excessively crowded, resulting in spindly stalks, smaller leaves and production of seed stalks these are all signs that rhubarb needs to be divided. Be sure to cut off any seed heads as soon as they appear.

What to do? Provide rhubarb plants more space, divide the parent plants and fertilize regularly. Wait until early next spring to divide rhubarb, as summer time is too hot, and fall rhubarb transplants need to be thickly mulched to help them winter over.

Did you know? Rhubarb leaves contain high amounts of oxalic acid, and may be toxic if consumed. Be sure to remove leaves from rhubarb stalks before using and discard or compost them.

For further information on growing rhubarb or other gardening questions, contact Yvonne McCormick at yvonne@iastate.edu