Bare-root strawberry plants often arrive with roots that are 6 to 10 inches long. For optimal planting, the roots should be kept straight, which requires digging a deep hole or using specialized tools. If the planting hole is too shallow, the roots may bend and form what is known as a ‘J-root’.
You may have heard experienced growers say, ‘Never plant bare-root strawberries with J-root’. But the reason why isn’t always obvious. To better understand the issue, we did an experiment by planting bare-root strawberry plants in pots, some with straight roots and others with J-roots, and observed the differences.
Both sets of plants grew well in the greenhouse, and I couldn’t see any noticeable difference in their aboveground growth. However, when I removed the plants from the pots to examine their root systems, I found a clue that may explain why J-rooting can be a problem.
The plants in the photo were grown in 6-inch pots for about three weeks in a greenhouse. The ones on the left were planted with J-roots, while those on the right had straight roots. During the three-week growth period, most of the new roots developed from the lower end of the original roots. These new roots are fine and thin, but there are a lot of them. The arrow in the photo pointed to the new roots.
When bare-root plants are planted with straight roots, the new roots develop several inches below the soil surface. But when the original roots are curled during planting, the tips end up near the soil surface, and the new fine roots also grow close to the soil surface.
We also observed a few thicker roots emerging from the crown, with no apparent difference between the two planting methods. This is not surprising, as crown root development is influenced by the depth at which the crown is buried, a factor that did not different between the treatments in this study. Although we did not monitor root growth over time, there appeared to be a trend in which initial root development occurred primarily along the old roots, particularly on the lower half of the root system, followed by the emergence of new roots from the crown.
Does the initial root growth pattern matter for plant survival and growth? A study conducted in Florida compared bare-root strawberries planted with J-roots and straight roots on plastic-mulched beds. The plants were irrigated intensively for 10 days after transplanting. Researchers found no significant differences in plant establishment, growth, or yield between the two planting methods. They concluded that when proper irrigation practices are followed, the way roots are positioned during planting may not be critical. You can find more details about that study here. Similarly, in my greenhouse experiment using soilless substrate in pots and watered daily, J-rooting at planting did not seem to affect plant survival or above-ground plant growth.
However, understanding the differences in initial root growth between J-rooted and straight-rooted plants can help explain why planting technique matters under less-than-ideal conditions. When soil moisture varies widely after transplanting, bare-root strawberries planted with straight roots are more likely to survive. That’s because their newly developed roots are located deeper in the soil, where moisture levels are more stable compared to the surface.
Special thanks to Indiana Berry for donating the bare-root plants and encouraging us to explore this topic.