Caring for native trees in the garden

…and a list of what to plant

Toxicodendron diversilobum Poison oak under the trees is a hazard in the garden

When faced with a new, mountain or rural garden, you need to make peace with your oaks and pines. These beautiful trees can be unkempt, stickery and surrounded by brush and poison oak at the start. I wondered what could be planted under them with their dry shade and falling leaves.

Here are a few things we did to fit our garden around these stately trees:

Protect them

First, we protected them from damage, from construction equipment by marking off our trees as “out of bounds” to construction equipment before building. One sad homeowner in our mountain community has lost close to one hundred trees around his luxury home, by neglecting to do this. Compaction from heavy equipment, irrigation drip lines and grade changes are bad for oaks and pines.

2001-Trimming the oaks to reveal the huge rock

Groom them

Grooming the branches and brush, 10 feet up and ten feet around our trees allow us to walk safely under them and see down through them on a slope. We cut poison oak off at the base and then spot spray the new sprouts with aa systemic herbicide for several years. Raking and a light covering of gravel, river rocks, pine chips or needles make a neat appearance.

2006- Planting Western sword fern and heuchera

Plant under them

Oaks must have dry roots in summer.  Oak fungus can grow in moist soil and slowly kill the tree. Clusters of plants arranged around accent rocks outside a 4-5 foot diameter circle all around the tree work, and planting in the fall or after the first rains means you won’t need to provide extra water while the plants adjust to their new homes. Between two oaks here  is a natural winding drainage area about four feet away from each oak. The water flows down through and I put rocks along the natural curves to slow it and planted Douglas iris.

Planting under pines, thyme, ajuga, Lamb’s ears, California yarrow, behind

Under pines, plants with open habits like rhododendrons or Western azaleas work well because the needles just fall through their leaves. I plant rhododendron, iris, lilac, lilies and viburnum in small groups just inside the drip lines of our pines close to the house.

2009-Planting under oaks, Helichrysum ‘Moe’s silver’, Blue fescue, Lamb’s ears

Under one oak, I planted Helichrysum petiolare ‘Moe’s silver’ and Blue fescue, Festuca ovina ‘Glauca’ and I’m pleased with the silvery-grey carpet near it’s base. Helichrysum is ‘evergrey’ and needs so little water that’s I consider it a very valuable Mediterranean in the garden.

2008-Planting under oaks Leave a space around the trunk, Artemesia, wild rose, sage

Under oaks and pines these plants need little water and work well if kept about four feet away from tree trunks:

Columbine, Aquilegia formosa
Low-growing Manzanitas, Arctostaphylos
Artemisia, any
Oregon Grape Berberis or Mahonia aquifolium
California native bulbs, Brodiaea and Triteleia
Catmint, Nepeta faassenii
Helichrysum, any
California wild lilac Ceanothus, any
Soap Plant, Chlorogalum pomeridianum
Ferns: Wood Fern, Sword Fern, Maidenhair Fern
Alumroot or coral bells, Heuchera
Douglas Iris hybrids, Iris

Planting under oaks, Helichrysum ‘Icicles’, Golden oregano, Lamb’s ears, Rosemary

Rosemary
Western Wallflower, Erysimium capitatum
Pacific Woodrush, Luzula comosa
Sulfur Flower Eriogonum umbellatum  ‘Shasta Daisy’
Autumn sage, Salvia greggii
Bush Monkeyflower, Mimulus aurantiacus
Purple Needlegrass, Nassella pulchra; also other native grasses
Evergreen Currant, Ribes viburnifolium
Lamb’s Ears, Stachys byzantina
Snowberry, Symphoricarpos albus laevigatus
Blue fescue, Festuca glauca
Dusty Miller, Senecio cinararia

2008-Planting under oaks, lavender, heuchera, fern, sage, iris

All these plants I hand water during the hottest part of the summer and some have light sprayers for when we travel.  I’m happy that I’m being able to replace spray emitters with more and more ‘goof plugs’ because the plants are established enough to do without.  With proper care our oaks and pines to have long, long lives and be a pleasure all through the seasons.

2008-Planting under oaks, Cleveland Sage, White sage, Lamb’s ears