August Gardening Calendar

Warm to hot days with cooler nights are the general rule for coastal Humboldt County. Exceptions are portions of the coast where hot weeks may alternate with foggy cool ones, and coastal inland valleys where daytime heat lessens after dark. One-half of a percent of our annual rainfall comes during the months of July and August, mostly in the form of an early morning foggy drizzle.


Watering is by far the most important task. Only a garden of native plants can be left without a "sitter" for more than a week. Every day some part of the garden needs extra moisture. Do not rely on surface appearance but check a foot or two deep where the roots are. Low humidity this month damages many plants. If camellias, azaleas and rhododendron get dry for even a short time, they may drop many of their flower buds. Nightly hosing of the foliage, after the sun goes down, refreshes these plants, as well as tuberous begonias and fuchsia flowers. Camellias in containers will need almost daily watering. A mulch over the soil will help, as will wrapping the container with several layers of burlap. The sun's rays, shining on a black flowerpot, may raise the temperature of the potting mix to above 100 degrees, causing a rapid loss of water and a great deal of stress to the plant.

Start disbudding camellias now. Most varieties have much larger and prettier flowers if all but one flower bud in a cluster are removed. Allow one flower bud for every three inches of stem. You can tell the flower buds from the leaf buds because they are fatter.

Most perennials, such as delphinium, coreopsis and Shasta daisy, are at the end of their bloom cycle. But if they are cut back, fertilized with a balanced plant food and kept watered, they will produce another crop of flowers this fall.

Madonna lilies are planted now, though other lilies are planted later. If gophers are a problem, set the bulbs in a hardware cloth basket, made deep enough to extend one inch above the surface and wide enough to accommodate the bulb and two or three inches of roots. Baskets are available at the nurseries, or you can make your own. Hardware cloth is good, chicken wire baskets rust out in a few years. I build my raised beds on hardware cloth also, keeps the critters from digging in.

Citrus need regular watering, about once a week in sandy or silty soil, and more often in hot weather. If they get too dry they will drop their leaves and fruits. Fertilize young citrus once a month. Those in containers should be fed every other week. Watch for, and spray for aphids, mite, and scale. One of the largest growers of dwarf citrus recommends malathion for all three of these pests.

Dahlias are at the peak of their beauty. Be sure their heavily laden stems are securely staked and tied to prevent breakage. Watch for mildew and at the first sign of it spray with an all-purpose fungicide-insecticide. Water heavily once a week, filling a basin around the plant.

Fuchsias are also at their prime. Most fuchsia hobbyists drop nitrogen from the twice-monthly fertilizer program at this time, and use a 0-20-0 fertilizer to keep the flowers coming.

Top perennial of the month is phlox. The showy heads of fragrant blooms give an opulent effect to the summer border. Pink varieties are especially pleasing with clumps of steel-blue globe thistle or clear blue veronica. They combine well with edgings of petunias, ageratum or lobelia. White phlox adds a soft glow to the garden at night.

This month the Cornish heaths come into bloom. Three varieties, 'Mrs. D.F. Maxwell', 'Lyonesse' and 'St. Keverne' are a mass of pink and white appreciated by the hummingbirds.


Every season I audition several new or promising plants. Two outstanding plants that I have added to my summer repertoire are an annual and a bulb. The annual is the dwarf Godetia 'Satin Mix' (actually a Clarkia) available at most nurseries in six packs in the spring. This easy to grow foot-tall plant spreads out two feet and is covered in blooms all summer. Colors are soft lilac through pink and white. Pinch the tops as they grow and the plant will reward you with multiple blossoming stems. Shear the tops when done flowering and you may get another flush. They reseed, but the progeny reverts to a lackadaisical lavender color.

The bulb is the tongue-twister Rhodohypoxis baurii platypetala (I sure hope someone comes up with a common name soon on that one!) and I purchased this at the now-closed Harris Street gardens in Eureka. After separating clumps of the tiny bulbs I spread them around in a rock garden where they happily multiplied. My original purchase was a four inch pot, and the area after several seasons had exceeded several square feet. The grassy foliage is approximately three inches tall with the numerous one-inch white flowers carried slightly higher.

Rhodohypoxis baurii platypetala

The effect is stunning with Blue-eyed Grass (Sysirinchium bellum 'San Bruno Mountain') and Blue-star Creeper (Laurentia fluviatilis), with Lobelia 'Crystal Palace' as a solid splash of rich dark blue color. You could use the 'Cambridge Blue' Lobelia if you needed a softer blue, but this lobelia would require a little more protection from the sun. Rhodohypoxis is also available in pink and rose red.

It needs summer water and must have good drainage, but it's best kept cold and dry during the winter when it goes dormant. After one particularly wet winter this dainty little bulb did not reappear. They are easiest when grown in pots which can be pulled out for storage during the wet season. It excels as a bonsai garden plant.

OK, since you insist; roe-doe-high-POX-sis boar-ee-eye plate-tee-PET-uh-la, I think, but you don't have to be able to pronounce it to grow it.


Shrubs are the major structural plants of your yard, and almost as permanent and dependable as it's architecture. There are hundreds--evergreen and deciduous, short and tall, flowery or mostly foliage, sun-loving or shade-tolerating. Their uses are as varied as their appearance. Before you can make wise selections, you must decide where and when you are going to use each shrub, and the requirements it must meet. Then scan the available plants to see what fills the bill for you (yeah, all well and proper, but many gardeners do as I do--buy a plant because they like it and then look for a spot for it.) Usually your choices boil down to only a handful of topnotch candidates. There are even computer programs that can assist you with this task. Sunset produces a CD-ROM, which determines from your answers to certain questions, including your ZIP code, what this ideal candidate would be. Someday when we have time we'll add something similar to this web site... Some day when we have time, my mantra.

The ideal shrubs look well the year around. Evergreens of course are superb, especially for entrance plantings and for areas that you see from your windows during winter. But deciduous shrubs are interesting also, even when leafless. Flowers may or may not be important. For example, with hedges and screen plantings, dense, healthy foliage is what you are after and blossoms are a secondary asset.

Take into consideration each shrub's eventual mature size and shape, so you will not have to keep pruning it to try to make it fit a smaller site. And plan spacing according to future needs. All bushes are deceptively small to begin with, unless you buy big, old specimens, so you can be fooled about how large they will become in a few years. The first season after planting they will grow very little, while roots become established. But within three to five years they will achieve full size. They grow best when not crowded, so if you buy too many and cram them into a small space you waste money, and the plants do not do as well as if you had set out fewer. You can plant annuals to fill the empty spaces between shrubs while they are small.

The best time to plant is fall through spring.

Sun angles for August

August sun passage, click to enlargeEnlarge image

During August, at a latitude of 40° north and at solar noon, a board fence six and a half feet high will cast a shadow that is three-and-a-half feet long to the north, more so during the the rest of the day. The sun's altitude (elevation) will peak at approximately 60°, or a little shy of three-quarters of the way up the southern sky.