The correct rhubarb crown planting depth is 1 to 2 inches (2.5 to 5 centimeters) below the soil surface. Set the buds just under the dirt and the shoots will push through with no trouble. Go too deep and your rhubarb will waste energy fighting its way up through extra soil instead of growing strong leaves.
When you plant rhubarb crowns, start by digging a hole that's about 12 inches wide and 12 inches deep. This gives you room to spread the roots out flat without bending or cramming them. Mound some loose soil in the center of the hole so the crown sits up on a small hill. Set the crown on top of the mound with the buds pointing straight up. Fan the roots down and out around the sides of the mound. Backfill with soil until the buds sit just 1 to 2 inches below the surface. Press the soil down firm with your hands so no air pockets remain around the roots.
Getting the rhubarb planting depth right matters more than most new growers think. MIgardener warns that it is very important not to bury the crown too deep. Ohio State Extension adds that plants should sit 3 to 6 feet apart to give each crown room to spread. When you combine the right depth with proper spacing, every plant gets a fair shot at building a strong root system. Crowding plants together forces them to fight for water, light, and nutrients from day one.
I made the mistake of planting one of my crowns about 4 inches deep during my first year of growing rhubarb. The other crowns in the same row were set at the right depth. The deep one took three extra weeks to show any green above the soil. When it did come up, the shoots looked thin and pale compared to its neighbors. I dug it out that fall and replanted it at the correct depth. The next spring it came up right on time with stalks that matched the rest of the row.
The biology behind this is simple. A crown buried too deep has to push its shoots through several extra inches of soil before they reach sunlight. That uses up stored energy the plant needs for leaf growth and root development. Every bit of energy spent fighting through dirt is energy that doesn't go toward making the thick stalks you want to harvest. A crown at the right depth sends its shoots into the sun fast and starts building leaf area within days of poking through.
Water your new crown in well right after planting. Give it a long, slow soak that sends moisture deep into the hole where the roots sit. This settles the soil around the roots and removes any air gaps that could dry them out. Keep the soil moist but not soggy for the first few weeks while the roots take hold and start growing into the ground around them.
Stick to that 1 to 2 inch depth and your rhubarb crown will come up strong every spring. Check the soil level around your crowns each fall because frost heave and rain can shift the dirt. If you see buds showing above the surface, add a thin layer of compost on top to bring them back down before winter sets in. Getting the depth right from day one gives your plant the best shot at a long, productive life in your garden. You'll notice the difference in stalk size and timing right from that first spring emergence. Take the time to get this one detail right and everything else falls into place.
Read the full article: Growing Rhubarb: Expert Advice for Success
