Washington State University Extension

Garden Tips


GARDEN TIPS – written by Marianne C. Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Written July 16, 2015


I adore flowering annual plants and have eight large pots lining my patio. They provide delightful color all summer long. However, many annual flowers are not particularly heat tolerant and stop growing and flowering during the hottest part of summer. The trick is selecting only types and cultivars that are heat tolerant.

My top five favorites annuals that do not fail even in hot summer weather are:

Wave Petunias and Others: I admit to being a big fan of Wave petunias and have previously talked about them at length. They still can not be beat for their ability to keep flowering throughout hot summer and early fall weather. I currently favor the Easy Wave petunias because they have a more mounded trailing habit and don’t become as leggy in late summer. They are available in a variety of colors, including pinks, purples, red, burgundy, yellow, coral, plum, and white.

Despite my devotion to Wave petunias, I still like to give other petunias a try. The Charm series from Proven Winners also have excellent heat tolerance and a mounded, trailing habit. I am “charmed” because even though the flowers are relatively small, the plants stay covered with colorful blooms all season long. This year I am growing Rose Blast Charm with bright raspberry and soft pink bicolor flowers. Wow!

Sweet Potatoes: These heat loving vines are prized for the colorful leaves. I tend to stick with the older cultivars, Blackie with dark purple leaves and Margarita with lime-green leaves. However, there a number of newer cultivars, including the Proven Winners Sweet Caroline and Sweet Caroline Sweetheart series. The cultivars in these series come in a variety of foliage colors, including light green, dappled green, yellow-green, bronze, dark purple, and reddish green.

Mealy Cup Sage: While they do not make the color impact of scarlet sage (Salvia splendens), I prefer the very heat tolerant mealy cup sage (Salvia farinacea). They make great upright “thrillers” in containers, are very heat tolerant, and have few pests. Plus, they are a magnet for bees and butterflies. I usually plant mealy cup sage cultivars with purple-blue flowers, but this year I came across one with white flowers called Evolution White, so I decided to give it a try.

Lantana: Not that long ago, I told you that I had discovered the beauty of the many newer cultivars of lantana. It seems like the hotter it is, the better lantana grows. In milder climates lantana is a woody perennial, but in our region they are used as annuals. When plant shopping this year I could only find a few cultivars of the Proven Winners Bandana series. They are all lovely with vibrant yellow, orange, cherry, white or pink flower clusters that open as one color and then the center flowers turn a different color. The Bandito and Lucky lantana series from other companies are also very nice.

Coleus: The fifth on my list of annuals are heat and sun tolerant coleus. Coleus of yesteryear did perform well in heat or full sun. A number of new coleus cultivars are sun tolerant, but they do not stand up well in extreme heat. Plant tags must say “heat tolerant” or I will not buy them. I am growing several of the heat tolerant Proven Winners ColorBlaze coleus series, including Lime Time, Sedona with orange-pink-bronze leaves, and Marooned with dark purple leaves.

Those are my top five. What are yours?

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