If you grow rhubarb plants in your backyard, it is important to remember that they need to be divided 4 years into growth. As the plant becomes established, the stalks will slowly start becoming thinner, and the plant will look more crowded. Dividing the plant at this stage is highly beneficial, as it will propagate new, healthier growth for several more years.
Step 1 – Dig out the Rhubarb Plant
The best time to divide a mature rhubarb plant is in early spring, when new growth has started forming on the plant. This will give you a better idea of the area to dig out. Choose a healthy plant for division. Use a garden fork and shovel to dig the area around the rhubarb deeply. Once the soil is loose and the plant is movable, pry it out gently, without damaging the crown.
Step 2 – Divide the Crown
Once the crown and the roots are out, examine the root system closely for any signs of rotting or disease. Discard the plant if the roots look unhealthy. If some small sections are showing signs of rot, you can trim them away and use the healthy parts. Start dividing with a sharp knife, so that the crown is split into 6 or 8 pieces. Each piece must have at least one ‘eye’ from which the new plant will grow. The eyes on the root system are quite fragile, and must be handled carefully. Each division must have a minimal cross sectional area of around 3 inches, or else the chances of propagation are lower. Examine each division thoroughly for signs of rot, and discard those parts. It is normal to see some signs of rotting, because the plant has been in the ground for a few years.
Step 3 – Prepare the Planting Spot
Store the roots in a shaded, ventilated place, preferably a pierced plastic bag, while you prepare the planting spot. Rhubarbs are best planted in a separate area in your garden, so that they do not interfere with other plants when they grow back every year. Rhubarbs require well-drained, fertile soil for optimal growth. After deciding on the planting spot, dig out the soil so that each division has a pit that is a couple of inches in diameter and depth. Remove all weeds. Keep a distance of 3 to 4 feet between each spot, so that the plants will have sufficient air circulation when they grow. Mix the dug-out soil with an equal amount of mature compost, and a small amount of all-purpose fertilizer. Back fill the soil till the planting spot is almost full.
Step 4 – Plant the Divisions
Place a rhubarb division in the planting spot, so that the top of the crown in slightly above the soil surface. Back fill the rest of the soil and compost mixture, firming the plant in place. Mulch the plant to prevent weeds and to encourage moisture retention. Water thoroughly.