I have a blueberry patch on the western side of my property that contains nine northern high-bush blueberry plants that are approximately five years old. The varieties include: Northblue, Northsky, Northland, Early Bluejay, Bluecrop, Jersey and Patriot. Given the variety of bushes, our harvest is staggered from early July to late August. Around the bushes I have a thick groundcover of pine needles, woodchips, Creeping Charlie, French sorrel and strawberries. The Creeping Charlie thrives, no matter how often I pull it up out of the mulch; the sorrel and strawberries struggle. I believe that the soil is too acid for the strawberries and sorrel. Although the Creeping Charlie attracts pollinators all summer, I want to be able to keep the creeping Charlie in check because it also tends to chokes out the interior of my bushes. Creeping Charlie might work as a ground cover when my bushes are much taller but right now it competes with my bushes for moisture and blocks air circulation. In order to make this area more self-reliant, I want to try to create a guild of plants that will cooperate naturally in this part of my yard. Given that my children want me to plant dozens more blueberry bushes somewhere in the yard; I had better figure something out that will work!
Step One: Determining the Needs and Characteristics of Blueberry Bushes
• Blueberries need full sun for optimal fruit bearing.
• Blueberry bushes have very shallow root systems and are sensitive to water fluctuations, requiring one to two inches of water per week from blooming to harvest. We are generously blessed with sufficient rainfall most of the year, but in the hot, dry weeks of summers, supplemental watering is required to ensure an abundant harvest of large fruit.
• Blueberries prefer very acidic soil, with a pH between 4 and 4.5, containing at least 4 to 7% organic matter.
• They are multi-stemmed shrubs, ranging in height from four to seven feet at maturity.
• Blueberry bushes have flat, mostly shallow roots that grow like a plate around the plant and may have a few deeper roots. They are stoloniferous, rooting from creeping stems above the ground.
• They are native to eastern North America and are naturally found growing in old fields, thickets, open woods and forests.
• Easy access to the plants is essential for harvesting and pruning. For increased production, annual pruning is recommended after the bushes are established. I have seen recommendations for spacing varying between 2.5 feet and 5 feet between bushes.
Step Two: Choosing companion plants for the Guild
In choosing companions, I am looking for plants that will perform the functions that are found in a healthy ecosystem. These include:
• plants that provide fertilizer (through nitrogen fixing or attracting wildlife that will leave nitrogen-rich droppings),
• plants that bring nutrients into the cycle (dynamic accumulators that have deep roots that can bring minerals up from the bedrock,
• plants that cover and protect the soil (create mulch, provide a living mulch),
• insectary plants that provide housing and food for beneficial wildlife over the longest period of time, and
• plants that help cultivate the soil with deep roots that penetrate, loosen and aerate the soil.
In choosing guild members, I want a diverse collection of perennial plants that thrive in USDA zone 5, with a preference toward native plants when possible. The biggest limitation to choosing companion plants seems to be the high acid requirement that blueberries have, so that is where I started my search. For ideas, I looked through one of the indices in Edible Forest Gardens: Ecological Design and Practice for Temperate Climate Permaculture, Vol. II by Dave Jacke & Eric Toensmeier to find plants that have similar soil pH needs.
Size and space requirements are also a consideration. If I planted white pines near the blueberries, I wouldn’t have to manually bring in pine needles every few years but I don’t have room for a white pine in this corner of my yard. Instead, I have planted several white pines in the wild part of our yard so that I won’t have to transport the needles far. I focused primarily on herbs because I want the blueberries to be the top canopy layer to take full advantage of the sunlight. Going through the index, I found these possibilities:
• Nodding Wild Onion (bulb)
• Fortune’s Groundnut (vine)
• Swamp Milkweed
• Wild Blue Indigo
• Golden Saxifrage
• Bluebead Lily
• Dwarf Tickseed
• Sheep Sorrel
• Cardinal flower
• Ostrich Fern
• Solomon’s Seal
• Meadow Beauty
Using the index was helpful because many of these herbs were unfamiliar to me and the index allowed me to expand my search. After I had a preliminary list, I went through the needs, characteristics, functions and drawbacks of each plant on my list to determine whether they would be good additions to the guild. Some I was able to eliminate because they had characteristics that would compete with the blueberries. For example, ostrich ferns and swamp milkweed are too tall to plant between the bushes, but I could put them at the edges of the guild as transition plants. Others, such as Goldthread, I removed from consideration because they didn’t fill many functions. Based on my research, here are my possible blueberry guild companions and why I chose them:
Lupine (Lupinus perennis) – A native, clumping herb that accumulates nitrogen, acts as a dynamic accumulator, provides shelter for beneficial wildlife, is a generalist nectary and will act as a ground cover to choke out weeds if it is sown thickly enough. Lacewings lay their eggs on the leaves and spiders hide in the foliage. It flowers in May, June and July. An early blooming flower will lure insects to the guild so that they will return when the blueberries are blooming. One drawback is that the plant is poisonous but my children are well educated on what is edible and what is not and I don’t allow my goats to forage in the blueberry patch.
Cardinal flower (Lobelia cardinalis) – A native, clumping herb with fibrous roots, it provides food for wildlife and is a generalist nectary. Hummingbirds particularly find the nectar appealing. I have wanted to get some of these gorgeous flowers for quite some time, now I have an extra reason. It blooms in August and September.
Fortune’s Groundnut (Apios fortunei) – A non-native (Asian) vine with tuberous, edible roots, it fixes nitrogen, provides shelter for beneficial insects and is a generalist nectary. Lacewings lay eggs on the leaves and parasitoid wasps shelter in the foliage. The plant produces delicious tubers along its rhizomes that are high in protein. Finding a source for this plant appears to be difficult but there is a North American variety (Apios Americana) that Native Americans cultivated for centuries. This variety does not have the same preference for strongly acidic soil but I might just give our native vine a try in the guild anyway.
Nodding Onion (Allium cernuum) – A native bulb with soft, grasslike leaves and a flowering stalk. The bulbs are edible in its second year. It serves as a generalist insectary and its mild, oniony scent may help distract insects that feed on the blueberries. Gentle harvesting of the bulbs can help loosen soil that becomes compacted over time.
Solomon’s Seal (Polygonatum biflorum) – A running herb that spreads by rhizomes with edible roots and leaves. It will also serve as a ground cover to choke out weeds. These will have to be planted some distance from the blueberry bushes to ensure the plant height does not block sunlight from the blueberries and that harvesting the roots will not disturb the shallow roots of the blueberry bushes.
Cloudberry (Rubus chamacmorus) – A native, clumping herb, it grows about eight inches tall, with edible fruit. It provides food for wildlife and is a generalist nectary, flowering in June
Meadow Beauty (Rhexia virginica) – A native, clumping herb, it grows between one and two feet in height, with edible greens and root. This tends to grow naturally in sandy, swampy areas on the coastal plain so it might be a challenge to grow it here without amending our clay soil with sand.
Wild Blue Indigo (Baptista australis) – A native, clumping herb with a deep taproot, it acts as a nitrogen fixer and provides shelter for beneficial insects and is a generalist nectary. It flowers in July and August.
Golden Saxifrage (Chrysosplenium americanum) – A native flowering herb that makes a very low, dense, prostrate carpet across the ground. The greens are edible and it is a nectary plant offering small greenish blooms in April, May and June. It prefers shade or part shade and abundant water. My blueberry patch might be too dry for it to thrive.
When I include plants that tolerate acidic soil, just not in such a high concentration, the list of possible choices grows even longer. To name just a few, I could include yarrow, maidenhair ferns, hardy kiwifruit, Welsh onion, hog peanut, American groundnut, wild ginger and borage in my garden if the acidity of the soil is slightly less than optimal for the blueberries. As I already have yarrow, borage and perennial onions growing elsewhere in my gardens, it will be easy to try including them in the guild.
I guess my next step will be to see if I can easily and affordably locate some of these choices….
-- "To forget how to dig the earth and to tend the soil is to forget ourselves." M. Gandhi