Design trends

What to Do in the September Garden

Grevillea lanigera is a good low water groundcover that attracts hummers

Summer is winding down. It’s still warm during the day but the nights are cool and there’s less and less daylight hours. The soil is still warm so it’s the perfect time to start thinking about planting. Like the saying goes, “gardening is a way of showing that you believe in tomorrow.”

Gardening makes us learn new things. If you water less frequently, some plants may decline or even die eventually. Remove those that do and replace them with plants that will thrive with less water.

Fertilize shrubs lightly one last time if you haven’t already done so last month. All shrubs, especially broad-leaved evergreens such as rhododendron, pieris, camellia, hebe, need to calm down, stop growing and harden off to get ready for the winter cold. Some plants have already set next year’s buds.

Roses especially appreciate a bit of fertilizer now, encouraging them to bloom another round in October. To keep them blooming make a habit of pinching and pruning off old flowers. Always cut back to an outward facing branchlet with five leaves. There are hormones there that will cause a new rose to grow much sooner than if you cut to one with only three leaves. You can always cut lower on the stem if you need to control height.

Deadhead flowering annuals and perennials in the ground as often as you possibly can. Annuals like zinnias and cosmos will stop blooming if you allow them to go to seed. The same is true of repeat blooming perennials like dahlia, scabiosa, echinacea and lantana. Santa Barbara daisies will bloom late into winter if cut back now. These plants know they’re on this earth to reproduce. If they get a chance to set seed the show’s over, they’ve raised their family. Try to remove fading flowers regularly and you’ll be amply rewarded. If you want to start perennial flowers from seeds this is the time so that they’ll be mature enough to bloom next year.

Now through October, divide summer blooming perennials like agapanthus, coreopsis, daylilies and penstemons that are overgrown and not flowering well. You can also divide spring blooming perennials like candytuft, columbine, astilbe, bergenia and bleeding heart but sometimes they don’t bloom the first spring afterwards due to the energy they use re-establishing themselves. If you’re on a roll out in the garden, go for it now.

It’s still a little hot to plant cool season veggies starts in the ground. They appreciate conditions later in September when the soil is still warm but temps have cooled. It is OK to plant seeds of beets, carrots, spinach, arugula, mustard, leeks, onions, peas, radishes and turnips.

If you aren’t going to grow vegetables in the garden this fall consider planting a cover crop like crimson clover after you’ve harvested your summer vegetables.
It’s never too soon to start planning for erosion control in those areas that caused you problems during last spring’s storms.

Cut back berries vines that have produced fruit. Canes of the current season should be trained in their place.

Spider mites are especially prolific during hot, dry weather. Sometimes you don’t even know how bad the infestation is until all your leaves are pale with stippling. Periodically rinse dust and dirt off leaves with water. Spray the undersides of infected leaves with organics like insecticidal soap switching to neem oil if they build up a resistance to one of the pesticides.

Now that you’ve taken care of your chores reward yourself by adding perennials to your garden for color in late summer through fall. Take a look at the garden areas that aren’t working for you and replant. Good choices include aster, chrysanthemum, coreopsis, and gaillardia. Abutilon (Flowering Maple) come in so many colors that you probably need another one in your garden. Petite Pink gaura looks fabulous planted near the burgundy foliage of a loropetalum. Don’t overlook the color of other foliage plants like leucodtendron ‘Jester’ or Orange Libertia in the garden. A favorite ground cover that hummingbirds love is grevillea lanigera. Consider it for those hot areas.

One last to do: Make a journal entry celebrating the best things about your garden this year.

Design trends

California Natives for Containers

Native Western Azalea are so fragrant you can enjoy their scent from a distance.

Adding California natives to my collection of container plants has been a goal for a long time. Besides attracting birds and wildlife to the garden they use less water than most container plants plus they are beautiful. Since I have limited ground to garden I mostly have containers and have been quite successful as long as I match the sun or shade to the right plant. You’ve heard it before: “Right Plant, Right Place”
So here are some tips on native plants that do well in containers.

At my front entry that gets morning sun only I have a huge coral bells (Heuchera micrantha) that started out as a cutting wrapped in wet paper towels that a neighbor had found growing at the edge of the forest nearby. It loves it here. Other plants like salvia would not be happy there at all.So it’s definitely the right plant for the right place.I ’ll have to divide and transplant it next spring but it blooms for such a long time and the hummers love it so I never want to disturb it.

Gardening in containers is easy. You can control the soil, water and light and the gophers can’t undermine your efforts. There are a lot of California native plants that do well in containers and I’m going to place them where both the birds and I can enjoy them.

For some of my largest containers I’ll choose from natives like Western Azalea (Rhododendron occidentale), Deer Grass, Chaparral Pea or Giant Chain Fern. Any of the taller growing ceanothus and manzanita would look great too by themselves or combined with smaller growing plants.

For small to medium containers I can use Conejo Buckwheat, Hummingbird Mint, Penstemon heterophyllus, Verbena de La Mina, Mimulus, Woolly Blue Curls or Coastal Daisy, These combine well with colorful Lewisia, Dog Violets or Wild Strawberry.

I might combine a madrone with a Canyon Gray Coastal Sagebrush (Artemisia californica) which grows about a foot high and will trail over the side of the container adding beautiful gray color to contrast with the rich green of the other leaves. I also like the combination of California Hazelnut, Deer Fern, Redwood Sorrel and Wild Ginger.

Some of the most dramatic containers utilize the concept of combining a thriller, some fillers and spiller or two. Not all my containers will use this formula but I seem to be drawn to those that do. Plants in nature can be quite random in the way they grow together and still be lovely. Containers need a bit more order to dazzle and direct the eye.

Thrillers act as the centerpiece of a container. They are usually big, bold and beautiful. Giant Elk Clover is one such California native that is an attention getter. Chilopsis linearis (Desert Willow) is another great subject for containers as it is slow growing and beautiful in leaf and flower. Other architectural natives that will catch your eye as the centerpiece of a container are Hardy Hibiscus (Rose Mallow) and Pacific Dogwood. The thriller goes in the center of the pot or if your container will be viewed from only one side it goes in the back.

Next come the fillers. They can be foliage or flowering plants but they should complement and not overwhelm your largest plant. Usually they have a mounding shape and I’ll plant several around the thriller. Good fillers include Heuchera micrantha and Western Maidenhair fern.

The last plants I’ll add are the spillers which are small and will soften the edge of the container. Redwood Sorrel, Wild Ginger and Miner’s Lettuce are good choices. California Fuchsia would look spectacular with its red or orange flowers and grey foliage spilling down the side of my container.

The best overall soil mix for natives in containers sharp sand and horticultural pumice added to a good potting soil. Never use perlite or that puffed up pumice because it will float and look terrible. Happy Container Gardening.

Design trends

Planting Under Trees

This hardy geranium looks great below tree canopies if spaced well.

Many of us live under oaks or are surrounded by redwoods. We know the value of trees in the landscape. Trees shade us in the summer. We anticipate their showy blossoms in the spring and enjoy their beautiful colorful foliage in the fall. You can hang a hammock between two of them or tie a rope swing for the kids from a large branch. Trees are our companions, but how can you create a garden under one of them with the Cal Fire regulations in mind? Here are a few general guidelines.

Low growing grounders are acceptable under trees if the lowest tree branches are at least 6 feet high and the plants are not continuous. This can reduce the chance of fire spreading from one plant to another. Small non-woody perennials can also be used if they’re well maintained and don’t create a continuous fuel bed. Don’t plant dense shrubs directly under tree branches which would create ladder fuels and keep them separated from each other. Limb tree branches at least 3x higher than any shrubs.

Planting under a mature tree can be a challenge. You need to avoid damaging their roots and your new plants will need to cope with dry soil, shade, root competition and ever-changing moisture and light conditions. You want both your new plants and your tree to thrive.

Meet your tree’s needs first. Some trees are more agreeable than others about giving up some of their ground. You can still plant beneath trees that are sensitive to having their roots disturbed but you’ll need to make a few concessions. When purchasing plants to grow under trees, think small. Small plants require a smaller planting hole and this will minimize disturbance to the roots. You may have to buy more plants but you’ll have an easier time tucking them among the roots.

Don’t alter the grade of the soil around a tree or change the soil pH very much. Even adding a layer of soil that is more than 2 inches deep can reduce the amount of moisture and oxygen available to the tree and hinder gas exchange to existing roots, causing trees to suffer or even die.

Only the toughest plants have a chance of surviving among the surface roots of shallow rooted trees. Be careful when disturbing sugar maples, elms. cherries and plums, dogwoods, magnolias, pines and oaks. The majority of a tree roots are small woody roots and fine hair roots that grow within the upper 12-18 inches of soil and extend far beyond the trees drip line. These roots are responsible for absorbing water and nutrients from the soil.

If you encounter a root larger than 1 1/2 – 2 inches in diameter while digging a hole for a plant, move the planting hole a few inches away to avoid slicing through the root. You will sever mats of small tree roots when digging, but they’ll regenerate fairly quickly.

To avoid wounding the bark, which may cause insect and disease problems, start planting at least 12 inches away from the trunk. Oaks shouldn’t have any plantings closer than 6-10 feet from the trunk and those should be drought tolerant. After planting, water to settle the soil and spread 2-3 inches of mulch to conserve moisture and keep weeds down. Be sure to keep mulch at least 12 inches away from the base of the tree. Mulch can hold moisture against a tree’s bark and cause rot and disease.

So what plants will transform your bare patch of hard earth and knobby roots into a shady nook? If you’re going for a lush look, consider hostas and ferns, paired with the hardy geraniums like Biokova or Carmina. Other good companions are astilbes with their feathery flower plumes and variegated euonymus fortunei with bergenia or digitalis mertonensis with liriope, lamium, vinca minor, hellebore or brunnera.

Trees with branches limbed high look good with small shrubs planted underneath. Red-leaf barberry can brighten up this spot and also provide fall color. Small nandinas like Harbor Dwarf make a good ground cover and their foliage takes on an orange-red color in winter. Fragrant sarcococca grows well in this situation, too.

Low groundcovers make a simple statement under the crown of a tree. Ajuga, pachysandra and sweet woodruff all grow well here. Or you might like the look of the shade tolerant grass-like plant like carex morrowii ‘Evergold’. This stunning sedge makes a beautiful clump 1-2 feet high and 2-3 feet wide with dark green leaves and a central band of creamy white.

You can have a beautiful garden under a mature tree by following these tips.

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