Keep your garden looking good with potted perennials

It was the genial Barry Sterling, proprietor of Iron Horse Vineyards near Forestville, who introduced me to an effective way to maximize the pretty displays of perennial flowers throughout the growing season. And it wasn't to grow them in mixed drifts in a bed or border.

His idea was simple. Grow them in containers and set them along the front steps when they are blooming, and when they finish blooming, remove them to a potted plant holding area around back, or otherwise out of sight, because little in the garden is less interesting than most perennials when they are just foliage.

But when they're blooming, they are a triumph of taste and beauty, far more than most annuals. The problem is that most perennials have a short season of bloom — often 10 days to three weeks — and then that's it. Annuals, on the other hand, pump out tons of bloom all season long, but they tend to overwhelm with color. There's nothing subtle about a container of blazing orange zinnias or a pot of purple petunias.

If you'd like to try Barry's trick, there are a few things to know about container-grown perennials. A perennial is any herbaceous, or not woody, plant that dies back to its roots in the winter or, at least in our climate, slows down and hangs out until spring. When the cold weather comes, it's a good idea to cut the perennial's stems back to 2 or 3 inches. It will send out new, succulent growth in spring that will maximize flowering.

Also, because your perennials will be in containers, they will easily become pot-bound after a season or two. This means the roots have grown so thick that they are curling around the inside wall of the container. When the plant is dormant in January or February, knock it out of its container. You will notice that it has made its growing point into two or more growing points called crowns.

You can use a knife, but it's better if you grab the root ball with two hands and pull it apart into separate crowns. Replant the healthiest looking crown into new, fresh soil in the container, water it in, and put it back in the holding area.

As for the extra crowns, pot them up and give them to friends, keep them yourself, or toss them in the compost pile. Your call.

Be aware that plants in containers get warmer and transpire more water than plants in the ground. And so water your plants in the holding area frequently as the weather turns warm. You want the soil in the pots to be moist, but not sopping wet. Make sure your pots have good drainage.

To suppress weeds, line the floor of the holding area with weed barrier cloth. You would be wise to spread a couple of inches of pea gravel over the weed barrier cloth to allow more positive drainage. Containers set right on the cloth will drain more slowly, and the soil may become soggier, which prevents air from reaching the roots. Perennials don't need a lot of oxygen, but if their roots are sitting in a swamp of retained water, most perennials will die.

Needless to say, growing your perennials in pots takes care of the gopher problem. But not the deer problem. If you live in an area where deer come to see what kind of salad they can make from your flowers, place the holding area next to a wall or deer-proof fence and attach bird netting from the wall or fence to the ground in front of the holding area.

When you see the plants start to send up flower stalks or show signs of impending bloom, keep your eyes peeled. As soon as you see any flower color, move them to the front steps, or to a deck or patio — anywhere they can be easily seen by you and by visitors. When the flowering is finishing up, move them back to the holding area, and bring out the next group that's just starting to flower.

They can be grown in cheap, plain plastic pots. Just slip them into good-looking ceramic pots that you've collected for their days in the spotlight, then back they go to the holding area while the fancy pots stay on the steps to hold the next wave of talent.

Consult the following information to create gorgeous perennial bloom through the growing season. These are suggestions. There are thousands of perennials to choose from. For more complete listings, visit sonomacountynurseries.com/nurseries for a listing of local nurseries that specialize in perennials for our climate. Google the individual perennial names to see images of the plants in flower.

Late Winter to Early Spring

All early bulbs such as daffodils, paperwhites, tulips, crocus, scilla and hyacinths do very well in pots.

— Iris reticulate (netted iris) 5-6 inches, deep purple flowers

— Aquilegia canadensis (wild columbine) 15 inches, red and yellow bicolor

— Brunnera macrophylla (Siberian brunnera) 8-12 inches, clear blue

— Dicentra spectabilis (bleeding hearts) 18-24 inches, deep rosy red

— Primua denticulate (Himalayan primrose) 8-12 inches, lilac and white

— Pulmonaria officinalis (Jerusalem sage) 8-12 inches, blue-violet

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Spring

— Campanula poscharskyana (Yugoslavian bellflower) 6-12 inches, pale blue violet

— Corydalis lutea, 10-15 inches, golden yellow

— Dianthus gratianopolitanus (cheddar pink) 8-10 inches, rosy pink

— Geum x borisii (hybrid geum) 9-12 inches, orange-scarlet to yellow-orange

— Tiarella cordifolia (foamflower) 6-12 inches, white to reddish white

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Summer

— Astilbe x arendsii (Hybrid astilbe) 12-24 inches, white, pink, and red hybrids are available

— Campanula rotundifolia (Bluebell, harebell) 6-12 inches, bright violet-blue

— Hemerocallis x hybrida (Stella D'Oro daylily) 6-12 inches, bright yellow

— Lewisia cotyledon (Lewis and Clark flower), 6-12 inches, shades of red

— Oenothera fruticosa (Sundrops) 12-24 inches, bright yellow

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Late Summer

— Ceratostigma plumbagoinoides (Plumbago) 6-10 inches, cobalt blue

— Dianthus biflorus (Greek dianthus) 10-16 inches, magenta

— Hosta lancifolia (narrow-leaved hosta) 15-24 inches, deep violet

— Liriope muscari (Big blue lilyturf) 12-18 inches, violet

— Stokesia laevis (Stokes aster) 12-24 inches, lavender-blue

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Autumn

— Aster Oregon-Pacific strain, 10-15 inches, white, pink, violet, blue varieties available

— Chrysanthemum hybrid (Asian short species) 12-18 inches, pink

— Colchicum speciosum (Asia Minor crocus) 8-12 inches, pale lilac to rosy lavender