The many possibilities of petunias in Sonoma County gardens

Ever cheerful, giving and forgiving, petunias are ubiquitous summer annuals.

They’re featured everywhere, gracing containers or used as bedding plants in large assemblies so over-the-top some would call them vulgar. Each year brings new color combinations with contrasting veins, striping, edging and hues.

Some petunia varieties change color as the blooms age and some fade to nondescript tones. If you’re buying plants that are already flowering, you might be able to see this. I confess to mostly using basic colors like deeply saturated magenta-burgundy and deep purple. Both are non-fading colors and held on plants that have very good frost and heat tolerance and that bloom uncomplainingly for months.

In terms of design, it’s easier to combine single-color flowers and more simple flower forms with other summer annuals that also grow well in containers. These include trailing verbena, the dangling bells of dwarf flowering maple (Abutilon), plumes of celosia, zinnias and other colorful summer annuals. But there is no unpleasant combination and endless scope of fun possibilities with petunias.

‘Wild White’

A very simple petunia I like for a naturalistic setting is the ‘Wild White Petunia,’ an ancestor of modern petunias from Annie’s Annuals and Perennials nursery in Richmond.

According to the nursery, the seed originated from the UC Berkeley Botanical Garden. This is a much larger plant than the modern hybrids that have been bred for compact growth. It’s upright, with simple large white upward-facing flowers. Long-blooming and scented of vanilla, especially at night, it attracts hawk moths as pollinators. This petunia is not demanding in terms of soil fertility and water use.

Other more unimproved cultivars that are easy to grow from seed are heirloom mixes called ‘Balcony Blend’ and ‘Old Fashioned Climbing,’ which include varieties with simple flowers in deep violet, pastel pink and white, some with veined throats. Both are available from Baker Creek Heirloom Seeds Co. in Missouri and Select Seeds in Connecticut.

Unlike modern hybrids, these selections are open in growth habit. They usually benefit from a cutback about halfway through the growing season to remove spent flower stems and stimulate new growth.

Open-growth-form petunias are nicely woven through other plants, in containers, or in the ground. Put somewhere you can catch the wafting evening scent of violet and vanilla and watch hawk moths visiting. A good way to see them is to go out at night with a flashlight. The moths’ eyes are iridescent, and you can see them with a flashlight, darting swiftly from flower to flower.

Fancy new hybrids

On the other end of the flower spectrum, I’m excited to try some new ultra-fancy large-flower hybrids and heirlooms available this year from Baker Creek Heirloom Seeds. These are the Superbissima line, imported from the Cerny Seed Co. in the Czech Republic.

Many of the selections use superlatives as descriptors. In common across the varieties are blooms a shocking 5 to 7 inches across, all melodramatically flounced and ruffled, many with contrasting violet-veined throats. Like characters in a romance novel, they’re filled with drama. Besides their incredible appearance, they are fragrant and very attractive to pollinators. A couple of varieties that stand out are ‘Superbissima Cerny’s Triumph Mix’ and ‘Superbissima Giant Alba.’

The color selection in the mix varies from deeply saturated magenta-burgundy through deep pink to the lightest pink, all with violet-veined throats. The plants are 1 to 2 feet tall. ‘Superbissima Giant Alba’ is a more compact plant that grows to only 9 inches tall but spreads to 28 inches wide with “white- and pink-tinted blooms with heavily ruffled edges and dramatically veined violet throats,” according to their description. I am envisioning it blooming alone in a pot by my door this summer.

An heirloom cultivar from Cerny Seed Co. dating to 1934 and sold by Baker Creek Heirloom Seeds is Karkulka. In contrast to the Superbissima line, its flowers are a more normal 2 inches across. It is single, crazily bi-colored bubblegum-pink and white with ruffled and frayed flower edges. Endlessly cheerful and optimistic, and an indulgence in frivolity, these flowers will delight.

Practically speaking, I suspect the ultra-large petunia blooms will suffer from overhead water irrigation, so try setting up pots or containers on drip irrigation or take extra care when watering from a hose. Slugs and snails will drool at the sight of the flowers, so they are probably best grown in a container.

Modern hybrid petunias, in general, do best with regular irrigation and high soil fertility. Add mulch to containers and soil along with compost. Apply a monthly application of granular organic fertilizer or weekly liquid fertilizer to keep these cultivars looking their best. Protect them from slugs and snails with nontoxic baits, as needed.