Regional Gardening Reports :: National Gardening Association

In the Garden:
Coastal and Tropical South
July, 2010
Regional Report

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Asparagus fern combines with Bordeaux Supertunia to beat the heat.

Joys of the Summer Garden

On a visit to a friend's garden for dinner, I found a perfect summer tableau. The centerpiece was a pot of petunias in full bloom sitting alongside a huge watermelon. The smell of roasting peppers was mouth-watering, until a breeze moved it aside to make room for heady jasmine coming from the back stoop. Such a night!

The petunia family
We fondly call any one of several flowering plants "petunias," but not all of them are truly the same species. Petunias are native to South America and are closely related to tobacco and tomatoes. The simplest petunia is a small velvety trumpet flower on a slim stem with a few leaves in white and pastel shades of pink and blue. Plant breeders began there, and today's gardeners have their choice of literally thousands of different, but true, petunias.

Two very popular modern petunia groups are known as 'Wave' petunias and 'Supertunias'. The main difference in the two is in their growth habits. 'Supertunias' are less than a foot tall and spread 3 feet in every direction with flowers all along the branches. Original 'Wave' and its double-flowered sister truly hug the ground and spread 2-4 feet in well-drained soil. 'Easy Wave' is a bit taller and spreads, while 'Tidal Wave' is more upright and taller than the others. Both groups respond well to being cut back and fertilized several times during the spring and summer and therein lies their appeal. Classic petunias and older varieties are much less heat tolerant and will usually go to seed by mid-July.

Calibrachoa looks like small petunias (flowers and leaves) on steroids and are most often sold by the descriptive name 'Million Bells' or something similar. While petunias have 14 chromosomes, calibrachoas have 16.They were developed in Japan and released publicly in 1998. The main advantage to growing calibrachoas is that they are self-cleaning; that is, their faded flowers drop off neatly to make room for the next bud to form. The result is a plant that looks neater more of the time.

Other heat lovers
The summer garden depends on plants that can brush off a thunderstorm, take on a drought and stand night time temperatures above 70 degrees and daytimes up to and including 100+. The stalwarts include several jasmines, asparagus fern, colorful coleus and two "new" plants that are fast becoming favorites, 'Diamond Frost' euphorbia and the truly wonderful trailing vinca. The Euphorbia family is famous for poinsettia and crown of thorns. While 'Diamond Frost' is not as showy as these relatives, it is more reliable, with colorful burgundy and green leaves and delicate white flowers that do not fail or fade. Trailing vinca (Catharanthus roseus) brings the pinwheel flowers and shiny leaves of traditional vincas to the 21st century without their considerable baggage. The plants march neatly for at least 2 feet, covered in large flowers, many with the classic white eyes.

Hot peppers
The best news for gardeners in our regions is that all these plants can be added to pots and beds for a midsummer burst, maybe even at a sale price. If you haven't grown hot peppers before, give them a try, too. Start with a large pot (10-15 gal) and a very well-drained potting mix. Find a spot in full sun close to a source of water. Peppers need great drainage, so if you use a popular mix that has fertilizer and water-holding crystals in it, amend it with half its volume of ground bark. Peppers will also need more fertilizer than the soil mix provides. Consistent applications of water and fertilizer are keys to good pepper growth. Let pots dry out a little between deep waterings; add fertilizer every 7-10 days. Hot peppers are easier to grow than bell peppers and many are conversation pieces. After all, the jalapeno in those nachos rates only 2000 Scoville units, but the cute Scotch Bonnet habaneros heat it up to 300,000+. Now that's food for thought.

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