Zone Denial?

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Zone Denial?

Categories: Blog, Garden Guru

For at least 6 years, most areas of the Greater Kansas City region have not had winter temperatures much below zero Fahrenheit. When I moved here 13 years ago I was constantly reminded of prior bitter cold in excess of -20F and that the area, save for some sheltered spots in the city was “zone 5” with minimum temperatures from -10F to -20F on average. Over the past 13 years of living here, the coldest we have recorded at Powell Gardens at our official weather station was -10F (rounded down). We have even had one winter with a minimum of only+17F! Have we migrated into a new warm zone 6 (average low between 0 and -5F) or are we just in a short mild stretch soon to be broken by a bitterly cold winter?

The region’s plants are showing our climate change. Our crape myrtles (Lagerstroemia) were just dieback perennials when I moved here but now are large shrubs and even small trees! Crape Myrtles are hardy above ground only to temperatures around -5F at best. Here, just outside our Visitor Center, gardener Shelly Bruellisauer poses next to our ‘Zuni’ crape myrtle (Lagerstroemia indica x L. faureri). Spencer Crews, Powell Gardens’ former Director of Horticulture and now Director of Omaha’s Lauritzen Gardens was astonished to see how large our crape myrtles have grown. It got down to -21F at their garden last winter! They cannot grow crape myrtles there.

Powell Gardens now has quite a few crape myrtles growing around the southern end of the Visitor Center and in the Perennial Garden. Acoma Crape Myrtle is a beautiful clean white blooming cultivar that is a Plant of Merit. Look for it just south of the Visitor Center’s Hummingbird Garden.

Hopi Crape Myrtle is a very good pink-blooming crape myrtle and can be seen just outside the Visitor Center. All the crape myrtles with these Native American names are hybrids with more hardiness than typical species. Many of the new hybrids are from the National Arboretum in Washington D.C. but many are also from Oklahoma. Look for dazzling red ‘Dynamite’ crape myrtle, purple-flowering ‘Catawba’ crape myrtle and several other cultivars in the Perennial Garden.

Lindley Butterflybush (Buddleia lindleyana) is another tender shrub that has not died back in many years and has become quite a large fountain of its pendant lavender blue flowers. This butterflybush is a favorite of hummingbirds and butterflies and can be seen just out the south end of the Visitor Center while young plants are along the steps down to the Fountain Garden. This butterflybush is sterile but does spread a bit by easily removed runners.

Mimosa (Albizzia julibrissin var. rosea) is another somewhat tender tree that is really becoming large locally. Hardy strains that originated from cold Korea are what we have at Powell Gardens — this strain is also much more refined and not invasive like typical southern strains. We have several mimosas around the north end of the visitor center including the new cultivar ‘Summer Chocolate’ with deep purple leaves. Summer Chocolate mimosa is from Japan and probably not as hardy as typical.

We are tempted to try some Camellias outdoors with these moderated temperatures. Depicted is true Tea (Camellia sinensis) in bloom in the Heartland Harvest Garden’s Seed to Plate Greenhouse. Yes this is the plant whose fresh young leaves are brewed into tea. Tea, Sasanqua and Oil Camellias all bloom in late summer to fall, while the large flowering C. japonica blooms in late winter into spring. We have the hardiest cultivarSochi‘ tea from Russia that may be a good hardiness trial in a sheltered spot in our area.
I had to throw in a picture of another “first” in our Heartland Harvest Garden. The Sapodilla (Manilkara zapota) have their first fruit forming. We have had a Sapodilla (its sap is the source of chicklets gum, and its fruit are a favorite in tropical climates) for many years and it has been an indestructible indoor plant with beautiful glossy leaves. Our new grafted for fruit varieties are performing as you can see. Maybe consider this plant as a good edible indoor plant — put it out for the summer and indoors for the winter.
Come out to see Powell Gardens crape myrtles and other plants currently flourishing in our zone denial. I feel we should always be pushing the envelope with our gardens, testing and learning more each year. By writing this I feel I have baited next winter to be a really cold one–it always seems the climate here wants to make a liar out of you. If the crape myrtles die back this winter, we will let them bloom next year on new growth from their roots and be none the worse for wear. Just be leary of spending big dollars to by a tree form one at a local big box store.