Pretty perennials to plant in your Sonoma County garden

While springtime may be the best time to plant ornamental perennials in our gardens-it’s not the only time. So don’t worry if you didn’t plant all the perennials you wanted many months ago. From mid-July through September, there’s plenty of time to set them in the garden, where their roots will have time to grow, the root hairs to make contact with the soil, and for them to get ready to sail through winter. And then, next spring, when they wake up and start growing again, they’ll be in every bit as good a shape as the perennials you planted in the previous spring, just not quite as advanced in their maturity.

There are some rules of thumb for planting in the hot, dry months of summer and early fall, though. Since we are no longer in the cool, moist throes of spring, our task now is to give newly-planted perennials conditions as close to spring as possible.

This means a thorough soaking of the soil where the perennials are to go, preferably with an overhead sprinkler to mimic a refreshing spring rain. Remember that by July in our parts, uncultivated soil is dry deep down, and so a gentle soaking over 8 to 10 hours will get water down to where the roots will plunge.

The word “gentle” is important here, so that the water penetrates the soil and isn’t applied in such quantities that it runs off the surface.

The sun is also blazing hot in July and August. Once the soil is wet and the perennials are put in, I cover them with a cardboard box for at least the first day, if not the first two days, depending on whether we’re in a foggy-morning (cool) period or a heat wave.

A day or two of complete shade won’t hurt the plants and will give them a chance to get set in the soil without having to respire so much water just to deal with the stark sunlight.

After that initial total shading, it’s good to continue to give them some shade. This may not be necessary if we’re in a cool and foggy stretch of weather, but if it’s hot and sunny, simply propping up a piece of plywood against a ladder, or other such homemade device to throw some shade, will help them get started without drying out.

You can also buy garden shade cloth- a fine mesh cover that cuts sunlight by about 50 percent.

This can be erected like a simple tent over the perennial patch or even just laid down over the plants with a few stones on the edges so it doesn’t blow off in afternoon winds-it hardly weighs anything.

Keep the soil moist but not sopping wet. After a week, you can expose the plants fully to the elements. The perennials should be acclimated to their new home by then, but keep an eye on them for any signs of stress, such as wilting, insect damage, or the predations of gophers and deer.

The easiest perennial to transplant is probably the herbaceous peony (Paeonia hybrids). They don’t mind their tuberous roots being moved any time of the year, although the best time to transplant them is in the fall after their foliage and stems die back. They may sulk a bit after being moved during the growing season, but they’ll recover.

Be aware that there are some perennials-usually those with tap roots-that resent being moved at any time. Tap-rooted perennials should ideally be sowed from seed where you want them in the garden.

That big tap root is by far the plant’s main organ for absorbing water and nutrients from the soil, so when you dig it up, it breaks the connection between plant and what it needs to live.

Perennials that shouldn’t be divided or transplanted include the Balloon Flower (Platycodon grandiflorus).

Despite its delicate flowers, it dislikes being disturbed. Bugbane (Cimicifuga racemosa) throws up lovely tall, slender wands of white flowers in shady parts of the garden, but don’t try to transplant it.

Orange-flowered Butterfly Weed (Asclepias tuberosa) has a deep tap root, but may self-seed some volunteers.

If you lift them carefully when they’re still babies, you may have success transplanting them to a new spot.

Hellebores don’t want to be moved and they don’t need to be moved. They just get more sturdy and impressive as the years go by. In moist shade, hostas (Hosta sieboldii) will naturalize and so don’t need transplanting, but snails and slugs as well as deer love them.

Use Sluggo for the snails and fencing for the deer. Monkshood (Aconitum napellus) makes a pretty blue statement late in the season, refuses transplanting, and every bit of it is poisonous, so use gloves if working with it.

Finally, we see Russian Sage (Perovskia atriplicifolia) ubiquitously here in the North Bay, with its silvery foliage and bluish flower spears, but don’t even think about dividing it.