Planting under California oak trees .

There are many plants that grow naturally under oaks in California. Some genera are common in most of California and are commonly associated with oaks.

Ribes, the currants and gooseberries commonly grow in oak forests/woodlands. On the north slopes the currants grow under the edges of the trees, gooseberries grow in the openings. On the south slopes the gooseberries grow up under the drip line of the trees and currants are in the deep shade. People wonder where the native birds went. Ribes provide flowers for nectar, nesting sites and berries for food. Does your yard have those?

Rhamnus, coffeeberry and redberry. The Rhamnus genera grow in association with oaks. We've had a number of people that want to plant 'that little oak with red berries'. They grow with the oaks and kinda look like an oak. The root systems are similar to oaks and commonly share resources with oaks. That is good.

Ceanothus, the California mountain lilacs usually do not grow in the deep shade of oaks, but love the edges, half day sun, or under deciduous oaks. Using Ceanothus or Arctostaphylos, you can leave the heavy mulch under the trees alone and plant the drip line(edge of tree canopy) to make the oak look landscaped.

Solanum, nightshades. The nightshades are common under the oaks in most of the coastal regions of California. Great bird plant that has decent looking blue flowers in summer. Plant Vinca major for the rats, Solanum for the birds.

Yerba Buena, Satureja douglasii grows in the leaf litter of Coast Live oaks, Canyon Live oaks and even Blue Oaks. Excellent along serene walkways and under benches as it's flat and it smells real good.

Satureja chandleri is a shrubbier form(1-2 feet) of Yerba Buena that grows under oaks in Southern California. A snoot will find this beaut is cute and smells mighty fine, huggy and makes a very clean mess of green.

Sad, ain't it? Huggy, clean, mess of green and you don't have one?

Elymus condensatus, giant rye is one of the few grasses that grows under oaks. Although Giant Rye will grow in full sun, particularly with regular water, it will grow well in full shade with no extra water in most of California. For those of you that seem to want a grassy prairie and don't know a buffalo from an, oh I guess I can't type that.

Diplacus , the shrubby monkey flowers love the edges and half day sun under oaks. Full shade is a bit too much for monkey flowers, but full sun is commonly too much. Those little spots of sun under the oaks where the halo of sun beams come together in the afternoon is where you plant these. Put a garden bench near that spot with Yerba Buena under it and the monkey flowers/ hummingbird sage as the feast to look upon.

Saliva spathacea. Hummingbird sage

grows great under the oaks. In the wild Hummingbird sage grows in full shade and into full sun. I've only seen a few spots where the weeds haven't overwhelmed the sage and stunted the tree. In one spot one plant had filled an area of 50X50 feet with the foliage just above the leaf litter making a carpet of green with pink/magenta flowers that the hummingbirds love.

The question is, is this thing really a sage?

Heuchera maxima and Heuchera micrantha.

The larger alum roots grow well under oak trees. They form a great interface between a wet spot and the trees. Full shade to part shade, Heuchera doesn't like full sun and tolerates the oaks very well.

Monardella villosa and some of the Coyote Mints grow under or at the edge of oak trees in much of California. Big hat perennial ladies, butterflies and hummingbirds like these. Nice flowers and they smell nice.

Lonicera hispidula and Lonicera denudata Let's see, honeysuckles are generally evergreen, have pretty flowers, need little care, are usually not eaten by deer, have berries for the birds and are decent to look at.

Toyon, Heteromeles arbutifolia,  grows under oaks in most of California. Near the immediate coast Toyons move into the sun but in areas like Los Angeles or Riverside, Toyons are mixed with the oaks and commonly grow even at the trunks.

Rhus trilobata, Squaw Bush grows under oaks in the interior coastal valleys. A deciduous sub-shrub that has great fall color and berries for the birds. Funny, the people who HATE deciduous plants are often the ones looking for 'fall color'.

Lepechinia fragrans and Lepechinia calycina both do well under oaks with little care. Pitcher plants can grow in full shade into full sun. Picture a six foot high shrub with digitalis-like flowers.

Keckiella cordifolia and  Keckiella antirrhinoides, grows great under coast live oaks, Keckiella breviflora grows great under the deciduous oaks , but has also done ok here under our coast live oaks. This is a deciduous Penstemon, dead stickus in winter, pretty flowers in summer.

Interesting photo, style looks 3d, I thought it was a scratch on my monitor.

Amelanchier spp., the Service Berries can be very interesting as a contrast to the oaks. In many of the coastal woods Service berry can become a mini-tree under the high shade of oaks. Sometimes you'll have the full 100 foot oak, then the 10 foot service berry 'tree' and under it either Satureja douglasii or Symphoricarpos or Lonicera. Sometimes there's even a Ribes between the lower plants  and the Amelanchier.

Symphoricarpos albus and Symphoricarpos mollis both are snowberries and both grow well under oaks. Thrashers, Thrushes, and other native birds use the berries as survival food in winter. The berries taste like Ivory soap, but I'm not a bird, maybe it tastes different to them.

Good things you should do

Bad or unhelpful things to do.

(Oaks usually do not die in years but decades. Diseases and funny anomalies occur first. 

Your tree is the only one in the neighborhood with tent caterpillars or powdery mildew. Your tree lost its leaves even though it's an evergreen tree. Weird things that you can't find, figure out or the 'experts' can't help you with are commonly caused by one or more of these things in the column below.)

Plant associated plants.

DO not plant junk that has never grown near an oak tree and needs a ton of water and fertilizer. Why would you expect a plant that grows in full sun along a river in Brazil to grow under your oak in California dry shade.

Leave the oak leaves.

DO NOT remove the oak  leaves from under the oaks. Bare ground and weeds gives the tree aids.

Think like a tree. Long term, no sudden changes, no tilling, disking, poop, or water.  Hang a hammock and put yourself in it. .

Short term stuff will kill the tree long term. Pansies and petunias are a cruel joke under an oak. (Native violets do grow under deciduous oaks.)

BUT, if someone else put a lawn under an oak and the oak hasn't died for the last twenty years you cannot just turn the water off. The tree has to regrow it's root system and imune system. That may take 20 years of slowly turning the water off, rebuilding the mulch and planting companion plants under it.

Prune out the dead stuff and trim the branches up off of the ground.

Do not prune the trees hard or in some weird manner like pollarding. Forcing new growth draws from the trees resources and often triggers a cascading failure in the system. Don't paint the wounds. Don't cut the limbs tight against the trunk. If at all possible don't cut into live wood at all. Clean your tools between trees.

You can wash the foliage off occasionally on dry, dusty years.

Do not put a lawn under the tree or you'll have either a sick lawn or sick tree. Oak trees in the west do not know what to do with summer rain. A heavy summer rainfall can kill a few oaks in the wild, a sprinkler under your old oak tree can kill it. There are no absolutes, you might be able to water for years and get away with it, or your oak dies the first time you water during the summer. It's kind of like chance of rain, but it's chance of death.