The root systems of blueberry plants are very different than those of other fruit crops, says Gary Gao, Extension specialist and associate professor of small fruits with The Ohio State University.
“Most plants use root hairs to take up water and nutrients. Blueberries don’t really have any root hairs — they just have smaller and finer roots,” he says.
The way blueberry plants absorb water and nutrients is very inefficient and getting good internal drainage can be problematic for growers. Poor drainage can lead to phytophthora root rot.
“Whenever we don’t have the perfect soil drainage, we tell growers it’s very important for them to build raised beds,” says Gao.
However, just raising the soil beds isn’t enough. Here are some tips to maximize a blueberry plant’s internal drainage:
What You’re Working With
Identify your soil type. Gao says it’s important to know what type of native soil you’re dealing with first by getting a soil map and then assessing the status of your soil.
Conduct a crude drainage test. To check your drainage status, dig a hole about a foot deep and fill it with water to see how long it takes to drain. After that, you’ll know what improvements to make.
Check your soil. Before thinking about putting a plant in the ground, Gao suggests getting a good read on your soil’s pH, soil buffer pH or lime index, salt content, organic matter, and nutrient levels. Keep the pH around 4.5 to 5.2.
“The closer you get to 4.5 the better off you will be,” he says.
Improve Your Drainage
Raise beds the right way. Gao suggests that beds should be approximately 4 feet wide and should be raised 8 to 10 inches above the existing grade.
“Elevate the root zone to improve the drainage, both surface and internal drainage,” he says.
It’s easy to assume you have good internal drainage when a blueberry patch is on a slope, Gao says.
“The only drainage you get is surface drainage — water drains off. But vertically you don’t really have [good internal drainage],” he says. “By building raised beds, you get both improved surface and internal drainage.”
Improve the soil structure. Adding organic matter to your clay soil of your beds can help improve your internal drainage.
After reading the results of your organic matter test, plan to add organic matter to your soil if it is below 7%. To get your soil to that level you can add compost, sawdust, or peat moss.
“Peat moss also makes the soil more acidic,” says Gao. “With compost you have to be careful because compost can add salts. A grower will have to measure the salt content, or what we call the CEC — the cation-exchange capacity — to make sure they don’t have too much salt.”
What Else Can You Do
Sometimes raising the beds isn’t enough to make a difference in your drainage. If you have standing water after three days in your beds or between your rows, or if you notice muddy soil in your soil probe after that time span, “roots in those raised beds are still not in a healthy situation,” he says.
Gao says you should consider other options to improve your internal drainage.
Install tile. “You may have to install tile drainage between rows to channel all that excess water away from the blueberry patch,” he says. “Drainage tiles might need to be added as an additional way to keep the entire patch well-drained.”
Use drip. Blueberries need moisture to keep growing, but not wet soil. During the growing season to maintain that moisture balance, drip or trickle irrigation may be an option to provide a steady supply of water to plant roots so that the bushes will not suffer water stress.
Water frequently. “During the summer, it’s a good idea to water 2 to 3 times a week versus one inch of water per watering per week to keep soil moist at all times instead of soggy wet for a couple of days,” says Gao.