By Jim McCausland, Sunset senior garden writer

Blue star creeper (Pratia pedunculata, aka Laurentia fluviatilis, and aka Isotoma fluviatilis) is one of the few ground covers blessed with sky-blue flowers—a rare thing in the plant world.

It's also very easy to grow if you live in a part of the West that has mild summers and mild winters, and has a long season of bloom (now through much of summer). I love it because it covers ground so well, and fills into the garden's cracks and crevices so well.

You can buy the sky-blue version, or darker blue versions such as 'County Park', 'Dark Blue', or 'Kelsey Blue', though the sky-blue forms seems toughest.

Plant in full sun or partial shade, keep it well watered, and you'll soon be seeing as much sky blue below your feet as above your head.

By Sharon Cohoon, Sunset senior garden writer

Santa Fe has beautiful gardens, but normally you don't get a chance to see them without an invitation.  Well, here's two.  You can visit four private gardens in Tesuque on June 1 by car.  Or you can visit four eastside gardens in historic old Santa Fe on June 8 on a walking tour.  Both tours are sponsored by the Santa Fe Botanical Garden and the proceeds go to the Garden.  For more information about either tour, visit the Garden's link or call (505) 428-1684.

By Jim McCausland, Sunset senior garden writer

Garden hydrangeas naturally come in the white/pink/red/purple/blue range, but in some measure, flower color depends on soil pH. Here are the principles.

White-flowered hydrangeas will always be white.

Some reds and blues will always be red or blue. Some two-tone (red- or pink-and-blue) will always be two-tone.

Some hydrangeas (like 'Masja', €'Nigra'€™, and €'Tricolor'€™) will be either pink or blue, depending on soil pH and aluminum content. More acid soil (lower pH) with more aluminum tends to produce blue flowers, while more alkaline or basic soil (higher pH) with less available aluminum tends to produce pink or reddish blooms.

For blue flowers, water aluminum sulfate in around the base of established hydrangeas at the rate of 1/2 ounce per gallon of water through the growing season. Only apply the solution after you’ve already watered the plant. You can buy aluminum sulfate at local nurseries or online from Hydrangeas Plus.

For pink flowers, mix lime or superphosphate into the soil at planting time (easiest if you're planting hydrangeas in big pots). Virtually every nursery and garden center sells these amendments. You can also scratch them into the soil around already planted hydrangeas, but in such cases the soil pH is only altered slowly, so you may have to keep at it for two or three years to see much change.

By Sharon Cohoon, Sunset senior garden writer

Santa Monica garden designer Nancy Goslee Power is an unapologetic romantic.  And her own garden, which we feature in our June issue, starting on page 51, which is now on the newstand, proves it.  Here's a preview peek.

The Weaver's Garden at The Arboretum of Los Angeles County, which Power designed, is further proof, we think.  Try walking through this woven archway without feeling a bit like a kid again.  I don't think it can be done.

By Jim McCausland, Sunset senior garden writer

In the mild part of the Pacific Northwest where I garden, lawns and most non-native plants usually need about an inch of water per week to thrive. But from May through September, Seattle-area rainfall averages just 1 to 2 inches per month. So unless you have a drought-tolerant garden, plants will go dormant (lawns), die back, or die completely if you don’t supplement occasional summer showers with serious irrigation.

Whenever it rains, it’s easy to just skip that week’s watering. But it’s smarter to measure each week’s rainfall with a gauge that measures precipitation in hundredth’s of an inch, then subtract that from the amount of water you apply. Very often you’ll find that several hours worth of drizzle only amount to one or two tenths of an inch, and though your plants have wet leaves, most of their roots are on the dry side.

To check rainfall, I use a type of gauge that’s been around for more than a century. You can buy one like it (and only part of the gauge is pictured here) for about $30 from The Rain Gauge Store. To check the amount of water sprinklers put down, I use another very old tool: the empty tuna can. It holds just over an inch of water.

When you water, apply it slowly. If it starts to run off before you've put down an inch, turn the sprinklers off and let it soak in before you continue.

By Sharon Cohoon, Sunset senior garden writer

Salvia x sylvestris 'May Night' gets more press, but 'Snow Hill' is prettier.  It consistently produces more blooms per cycle.  The clean white blooms sparkle even from a distance whereas you need to get close to 'May Night' to appreciate it.  And I get more bloom cycles from 'Snow Hill'.  It consistently reblooms three times in my garden; 'May Night' often only blooms twice, and the second time sparingly at that.

Why aren't more people growing this little beauty?

I've used the designation that the Sunset Western Garden Book uses for this salvia for this post, but you're more likely to find it as Salvia nemerosa 'Snow Hill' in nurseries and catalogs.  It is also sometimes called Salvia x superba.  But it's all the same plant.

If you can't find plants at your local nursery, you can mail order from Bluestone Perennials.

By Jim McCausland, Sunset senior garden writer

Jim and Paula Umbeck have such a lovely, mossy winter garden that we published it last January in a story called Let Your Yard Go Wild. But even then I regretted the decision: though this is one of the finest winter gardens I've seen, it's even better in late spring and early summer, when woodland plants run riot in western Washington.

Walking through this blissful, lakeside space yesterday afternoon, I saw several plants that deserve a place in more gardens.

Japanese Jack-in-the-pulpit (Arisaema sikokianum), far left, earns its keep with striking leaves and flowers that look like porcelain art. Japanese tassel fern (Polystichum polyblepharum), paired at center with a blue hosta, has a kind of coarse perfection that's irresistable. If you like more delicacy, go with maidenhair ferns (Adiantum), shown at right with the ground covering Blechnum penna-marina and a red Japanese maple.

I'm also taken with the many colors of heucheras used in combination (left), and with Podophyllum 'Kaleidoscope', pictured here with maidenhair fern.

You have a chance to see this garden for yourself. It's on the Northwest Perennial Alliance Open Gardens list next month. Join and you can visit.

By Julie Chai, Sunset associate editor

If you've not yet gotten your tomatoes in the ground, do it soon. You can still get seedlings of heirloom varieties at Love Apple Farm in Ben Lomond. The seedling sale dates are Saturdays, Sundays, and Wednesdays from 10 a.m. to 3 p.m. through May 31 (or while supplies last).

And if you miss this year's planting window, you can always swing by later in the season to buy gorgeous, biodynamically-grown tomatoes...

By Sharon Cohoon, Sunset senior garden writer

Twilight Thursdays.  June 5 through August 28.  A different event each week.  Possibilities include Brazilian music night, an outdoor movie under the stars, bluegrass music, and kid's pajama night.  The Garden stays open until 9 pm.

Weird Plant Sale  June 7, 8 am to 12 pm.  Weird plants and even weirder pottery promised.  Vendors come from all over Arizona for this yearly event.  Admission free for the sale.

How weird?  Take a look:

Tucson Botanical Gardens is located at 2150 N. Alvernon Way, just south of Grant Road. 

By Jim McCausland, Sunset senior garden writer

When Kinsman Company started offering border columns for summer annuals, we tried them in Sunset's test gardens. Results were spectacular.

Designed by Pamela Crawford, these elevated containers have coco fiber liners that are pre-cut with side planting holes, so the trailing and spilling annuals don’t get in the way of those growing out the top of the container.

Just fill each border-column container with a combination of trailing and upright annuals and vines, and within a few weeks bloom will be spectacular. Fertilize, water, and deadhead occasionally for a riot of bloom and texture all summer long.

You can get border pillars in different heights and use them alone or in combinations. To buy, go to Kinsman Company; for more information about plant combinations and techniques, to go Pamela Crawford’s side-planting web site.