Rhubarb is a perennial vegetable that requires a dedicated growing spot in the garden for 10 years or more. It will take a year to begin harvest and three to four years to come to full harvest.
Choosing the spot
You should take in consideration in advance the fact that you need bigger space for this plant since it grows over the course of about 10 years. You don’t want them planted too closely to each other, only to see (when they grow) that they don’t have enough space.
Choose a location in the garden where one or more rhubarb plants can grow for years. Each plant will require about 4 square feet (rhubarb can grow to 4 feet wide and tall).
Plant rhubarb in a sunny spot with fertile, free-draining soil. A soil pH of 5.0 to 6.8 is best for growing rhubarb. Prepare the site with organic material such as compost and manure, especially if the soil is sandy or poorly drained.
Plant in a raised bed if the soil is especially heavy and sodden. Use a good quality potting mix, and keep well watered through the summer – the large leaves really suck up the moisture.
Plant rhubarb in full sun
Rhubarb will grow in light shade. It grows best where winter temperatures fall below 40°F (4.5 °C) and summer temperatures do not exceed 75° (24 °C). Rhubarb is a hardy vegetable that prefers cool weather. If the weather is too hot, don’t forget to protect the plant with a shade cloth or the stalks will grow thin and spindly.
During warm spells (over 30˚C), flower stems can form. These should be broken or cut off before the flowers develop too much, as they grow at the expense of new edible stems.
Set rhubarb root divisions (called crowns) in the garden 4 to 6 weeks before the average last frost date in spring or as soon as the soil can be worked. Crowns can also be planted in autumn.
Don’t forget to prepare the planting hole
Prepare a planting hole 1½ feet deep and 3 feet wide. Add a handful of bonemeal to the planting hole and fill the hole nearly to the top with a combination of aged compost and aged manure or a commercial organic planting mix then pack the soil in. Set the crown or division 1 to 2 inches deep. The growing tip should be angled toward the surface.
Plant crowns or divisions 3½ to 4 feet apart in rows that are 4 feet apart.
Choosing bad companion plants
Since perennial plants such as rhubarb stick around for a long time, you should be careful when choosing its neighbors – you can plant Brussels sprouts, cabbage, and kale, but avoid planting root crops near rhubarb.
Under/Over watering
Keep the soil moist but not wet throughout the growing; do not let the soil dry out. Make sure that the soil around rhubarb does not puddle in winter to avoid crown rot.
Not knowing when to fertilize
Fertilize rhubarb beds with aged-manure in autumn and with aged-compost in spring. Side dress rhubarb with aged compost at midseason.
Other things to consider
- Mulch heavily around rhubarb – place a 2-inch-thick layer of aged compost around rhubarb during the growing season.
- Where winters are cold cover plants with 1 to 2 feet of straw to protect the crowns from freezing. Remove the straw in spring when the weather warms.
- Re-new rhubarb by dividing roots when stems become crowded and thin, usually every 4 or 5 years. Replant divisions in another part of the garden.
Mistakes regarding harvest
Don’t harvest to early. Rhubarb harvest can begin the second year after planting. Allow plants to establish roots the first year in the garden. (Even then harvest just two or three rhubarb stalks).
The full harvest of rhubarb can begin in the spring of the third year after planting, when plants are about 3 feet in diameter and stems are thick, red, and 12 to 18 or more inches long.
Be careful not to damage the crown – Pull stalks from the crown with a sideways, twisting motion. You can also cut stalks away with a sharp knife. Always remove and discard the leaves.
Do not harvest more than one-third of a plant’s stalks in one year – Allow inner stalks to grow on for harvest next year.
After harvest the remaining stems may die back – once they are brown and withered remove them.
Harvest should last 8 to 10 weeks – stop harvesting when the only stems left are short and thin.
