Blue oak, our most drought-tolerant native oak, grows throughout Solano and Yolo counties. In nature, blue oaks are mostly found on sunny, well-drained soils: “the wettest of the dry places and the driest of the wet places.” Nearby Rockville Hills Regional Park (Fairfield) and Lagoon Valley (Vacaville) contain excellent examples of Blue oak habitats.
You may have heard about keystone species. These are species that are useful in the lifecycle of a very large number of other species. Oaks in particular are keystone species due to their size, longevity, production of acorns and niches and protective branches, leaves, bark and roots that can house a host of large and small critters.
If you are fortunate enough to have a Blue oak on your property, or if you plant a Blue oak, you are guaranteed to have decades of enjoyment. In early spring, light green leaves will emerge on barren branches and gradually acquire their characteristic blue hue.
Before you begin your Blue Oak landscape, make a plan. Be sure to remove your lawn. Minimize hardscape under the oak canopy (define canopy?). Instead of pavement, use stepping stones, DG – decomposed granite, gravel, or permeable paving. Be sure to mulch to reduce weeds.
As you plan, remember that the Blue oak landscape is considered DRY SHADE. Some compatible species are evergreen, some are deciduous. Note that most deep-rooted plants should be planted several feet away from the tree trunk, even as far out as the edge of the canopy.
At the end of this article is a short list of native plants compatible with Blue oaks. They are grouped by form: Grasses, groundcovers, bulbs, wildflowers and low and tall shrubs. All of those listed are available at native plant nurseries and/or California Native Plant Society sales. CalScape is an excellent reference to use for locating plants.
Grasses: Native perennial grasses do quite well under Blue oak. California’s state grass, purple needle grass (Stipa pulchra) will thrive here. Other low-growing perennial grasses include Torrey’s Mellicgrass (Mellica torreyana), and California Fescue (Festuca).
Spreading Ground covers: California fuchsia (Epilobium), Yarrow (Achillea), and coyote mint (Mondardella villosa) will attract pollinators. If you plan to water these during the summer, make sure to plant on the edge of the canopy.
Many small shrubs will thrive along the canopy edge. Both California fuchsia and buckwheat are pollinator favorites. California fuchsia’s tubular red or orange flowers attract hummingbirds. Other small shrubs are the sages, prostrate coyote bush, and prostrate manzanita and ceanothus species.
Perennial Bulbs: Wild hyacinth (Dichelostemma multiflorum), native iris (Iris) Blue-eyed grass (Sisyrinchium bellum) and Ithuriel’s Spear (Triteleia laxa) will do well in the understory.
Wildflowers: Since Blue oak is deciduous and has a small canopy, there will be ample light in the early part of the year. Wildflowers commonly found in Blue oak habitats include Farewell-to-spring (Clarkia amoena), Chinese Houses (Collinsia), California Poppy (Eschscholzia californica), Lupines (Lupinus) and Baby Blue Eyes (Nemophila menziesii). Sow native annual wildflower seeds in the fall after the first germinating rain. Once established, many will reseed themselves.
Small shrubs will thrive along the canopy edge. Monkeyflower (Diplacus) and California fuchsia (Epilobium) are pollinator favorites. California fuchsia’s tubular red or orange flowers attract hummingbirds. Other small shrubs are the lower-growing varieties of Sage (Salvia), prostrate coyote bush (Baccharis) and prostrate manzanita (Arctostaphylos) and low-growing wild lilac (Ceanothus).
Tall shrubs for this habitat include: Gooseberries (Ribes), Pitcher sage (Lepechinia), taller manzanitas (Arctostaphylos) and Ocean Spray or Creambush (Holodiscus discolor). These should be planted farther out from the tree trunk.
Would you like online help with a plan? https://bayarea.calscape.org/wp-content/uploads/2022/10/111022_Woodland-1.pdf