Making the Most of Gardening Zones

No matter where we garden, we all have a bit of zone envy – the itch to grow something not suited to the heat, cold, moisture or dryness of our region. Gardeners in the North want tender tropical plants to survive their cold winters, while Southern gardeners try to grow plants that need more of a chill than their mild winters provide. But the desire doesn’t end there. Pick any growing condition that limits plant selection, and I bet you’ll find a gardener trying to grow outside the lines.

Pushing the Gardening Zone
Some gardeners try extreme measures. I met a wonderful couple in Southern California who had moved from the Midwest years before. They missed the fragrance and beauty of the lilacs growing in their Wisconsin garden, so they bought and planted one. When it was fully grown they created an artificial winter by surrounding it with blocks of ice—and were even able to force a few blooms!

An easier solution might have been growing California wild lilac (Ceanothus), which has similar flowers in white, blue and lavender—though, granted, minus the intoxicating scent. Most bloom in spring and are suited to Southern California growing conditions. In fact, I wish I could grow these beauties in the Midwest. But then again, I can grow lilacs.

Tulips, daffodils and many other spring-flowering bulbs also fall into this category, but it’s much easier to push their limits outside their gardening zones. Most of these plants need 12 to 15 weeks at 35 to 45 degrees to bloom. Areas with mild winters don’t have the necessary cold period, but you can push the envelope a little. Look for low-chill cultivars that bloom in milder climates. If there aren’t any suited to your region,
try precooled bulbs; growers give them the needed chill before you ever plant them. Or cool bulbs yourself. Plant in a pot of well-drained potting mix or pack bulbs in peat moss and put them in the refrigerator for at least 15 weeks. Then just plant and enjoy.

Try a New Breed

Gardening Zones Ian Grainger shutterstock

Many of the new plant introductions expand the regions and growing conditions of some old favorites. Gardeners in the Pacific Northwest have the perfect climate for growing hundreds of plants, but not tomatoes. Many gardeners in that area find cherry tomatoes the best option, but Bonnie Plants offers several larger-fruited varieties, such as Seattle’s Best of All and San Francisco Fog, which produce substantial tomatoes in the cool, wet coastal climate.

Gardeners who enjoy mild winters are justly proud of their blue and pink bigleaf hydrangeas, whose large, colorful blossoms are hard to beat. Most of the common cultivars bloom on old wood—so when these plants die back to the ground, so do gardeners’ dreams of glory. Northern gardeners try all kinds of winter mulches to preserve the flowering wood, and when winters are mild they sometimes get lucky.

Breeders have been working on remontant (reblooming) varieties that flower on old and new growth. Then, if winter destroys everything above ground level but the roots survive, the plants should still bloom. Endless Summer, Twist-n-Shout and Penny Mac are a few remontant cultivars. Providing ample moisture in spring and early summer, along with a low-nitrogen, slow-release fertilizer like Milorganite, will help boost the bloom.

Other Limitations
It’s not just the heat and cold that limit our growing potential and promote zone envy; soil acidity can do the same. Those gardening in sour or acidic (low-pH) soils may tire of liming, while those in sweet or alkaline (high-pH) areas long for blue hydrangeas, blueberries and red maples.

The bigleaf hydrangea is a very visible example. The flowers are pink in alkaline soil and blue in acidic soil where the aluminum is more readily available. Adding aluminum sulfate will help, although most gardeners end up with a muddy blue. Sometimes I think spray paint might be easier, but I’m sure the breeders are working on something.

You can also grow the plants in containers, where it’s much easier to control the soil environment. The super dwarf Jelly Bean blueberry forms a 1- to 2-foot mound and a bountiful harvest—perfect for small-space gardeners and those with high-pH soils.

Gardening Zone Substitutions

Like tropical plants or desert natives but don’t have the appropriate conditions? Consider growing your favorites as annuals or in containers, so you can provide the needed environment indoors or out. Or substitute look-alikes that will thrive in your climate.

The garden around the Thai Pavilion at the Olbrich Botanical Gardens in Madison, Wisconsin, uses cannas, bananas and other tropicals that can be overwintered as dormant rhizomes or grown as houseplants. The staff also uses a lot of hardy plants for a framework. Kentucky coffeetrees have been pruned to look tropical, and the native senna (Cassia) and some of the hardier ornamental aralias provide the look and feel of the tropics.

So don’t let gardening zones envy get the best of you. Pushing the limits and waiting to see what happens is one of the most fun – and sometimes humbling – parts of gardening.