Growing Wild Blueberries for Homeowners
Created by: Lily Calderwood, PhD, UMaine Extension Wild Blueberry Specialist and Mara Scallon, Extension and Research Assistant
Mainers young and old eagerly anticipate the summer months and its abundance of blueberry treats. Many Mainers enjoy making a day of raking and harvesting blueberries at a you-pick site, and increasingly more homeowners are looking to grow wild blueberry (WBB) right in their own backyards. Here are some key steps and processes that will help you to establish your own patch or encourage an existing patch.
Establishing a new wild blueberry patch:
- Soil. It’s important to plant WBB in well drained soils, like sandy soils. Do not plant WBB in clay soils. Identify your soil pH by taking a soil sample. There is a video of how to soil sample on the Cumberland County Extension website.
- Apply sulfur to decrease the soil pH to 4.0 – 4.5; see Fact Sheet 254 on the Cooperative Extension website for recommendations on applying sulfur. Note that sulfur should not be applied when the ground is frozen or saturated or when your WBB leaves are wet as you could burn your WBB leaves.
- To sample your soil, pick up a soil sample box and form from your local Cooperative Extension office. Using a trowel or small shovel and bucket, head to the location you’d like to plant WBB and gather multiple samples of soil by digging a few small holes 3-6 inches deep. Repeat ten times minimum, then mix these soil samples together in the bucket and use the resulting mixture to fill a soil sample box. Mail this box and soil sample form to the Maine Soil Testing Lab in Orono with $12 payment.
- Buy blueberry sod from a nursery listed on the UMaine Wild Blueberry Website (usually 1ft by 1ft, 3 inch thick blocks).
- Transplant sod to desired location. WBB can be planted as separate plants, in rows, or mixed in with other plants. Just like rhododendrons and azaleas, WBB needs full sunlight to grow best. You may need to prune nearby plants to maximize WBB exposure to sunlight.
- For the first two years of growth, you want WBB to put its energy into growing strong roots, so you must pinch off all blossoms for those first two seasons! Painful as this is to do, it will improve the long-term health of WBB substantially.
- Apply softwood mulch among sod pieces and in between blueberry stems. This adds organic matter and holds moisture, aiding in WBB root development. Softwood mulch is a good choice because it is already a lower pH material and it is readily available in Maine.
- Water or irrigate in the first two years so WBB can establish well in a dry season. WBB need 1 inch of water per week. If watering, don’t provide this water all at once – space it out over the course of the week. If there is adequate rainfall, there is no need to add supplemental water as this can cause disease.
Encouraging an existing wild blueberry patch:
- Mow the WBB patch in the fall (Oct/Nov) as low to the ground as possible. To mow, you can use a lawn mower, power trimmer, or flail mower on the lowest setting. Don’t worry, 75% of the plant is underground so you will not hurt the plants! WBB need to be mowed in order to produce berries in the quantities we want them to.
- If you want to produce berries every single year, you’ll need to develop a two year production cycle.
- Split your patch in half (approximately) and mow one half of the patch at the end of the season (in Oct/Nov, using a lawn mower, electric trimmer, or flail mower). Leave the other half of the patch unmowed.
- In the spring, you will see that your mowed patch begins to grow stems and buds and as the season progresses, the stems will grow taller but you will not see any berries. This is known as the “prune year” and the goal is vegetative growth for next year’s berry harvest.
- The other side which was not mowed will produce berries. In the fall, mow this side for berries the following year. In short, you will mow half of your patch every year, alternating
- sides. Berries will be produced on each field in alternating years.
- Burning blueberry plants is another way of pruning the plant, however this is not recommended to homeowners for safety reasons.
- Identify your soil pH by taking a soil sample. See note above about sampling.
- Apply softwood mulch among sod pieces, between blueberry stems, and so that bare spots are covered with 1 – 2 inches of mulch; this adds organic matter and holds moisture, aiding in WBB root development. Softwood mulch is a good choice because it is already a lower pH material and it is readily available in Maine.
- Water. WBB need approximately 1 inch of water per week in both the prune and crop years. Ensure your plants are receiving enough water and irrigate as needed.
- Manage weeds.
- Maintaining a soil pH between 4.0 and 4.5 reduces competition from grasses and broadleaf weeds. For woody tree saplings (e.g. birch, willow, alder) and ferns (e.g. sweet, bracken), cutting is the best management option. Cut these saplings and ferns to the ground 3 times each year. The goal is to let the plant put energy into above ground vegetative growth instead of developing a stronger root system. Cut the undesired plant, let the plant grow back again, cut it again, and repeat until the plant stops regrowing.
General best practices:
- Encourage pollinators! WBB are pollinated by a range of insect species including many native bee species and managed honey bees. Entice those pollinators to come to your WBB, as opposed to all those other flowering plants out there, by planting pollinator-friendly plants that bloom throughout the season. Consider how your use of certain pesticides might adversely impact pollinator populations.
- Sunlight. WBB grow best in full sunlight. If other plants are shading your WBB, you may need to prune or move those plants.
- Fertilizer. Keep in mind, fertilizers can feed WBB and weeds so fertilizing is not always needed. Fertilizers for acidic plants contain soluble ammonium nitrogen, which allow nutrients to be taken up in the acidic WBB soils. Organic gardeners may want to use products such as Pro-Holly.
If the plants are not growing or bearing well, start by looking at the following:
- Soils: are they acidic (4.0 – 4.5 pH) and well-drained?
- Sunlight: is there enough?
- Water: is there enough?
Still stuck? Contact Cooperative Extension: Dr. Lily Calderwood, firstname.lastname@example.org, 207-812-2915