Trailing nasturtiums, regal delphiniums, rainbow hued irises — all have been in riotous bloom for past few months, encouraged by cool days and light breezes.

But the long spring is on the way out, and summer conditions on their way in.

Now is the time to ask — what to plant in the garden once the spring annuals fade?

“That’s what Louisiana Super Plants are for,” said Dr. Regina Bracy of the Hammond Research Station of the LSU AgCenter.

“We test nearly 50 plants at a time to find those that can perform well during hot and humid days and warm nights.

“Plants in the Gulf South don’t get to rest at night like they do in other places because it doesn’t cool off, so Super Plants are those that can take those kinds of demanding conditions.”

Each spring and fall since October 2010, research station scientists have met with industry reps to review the group of plants that have thrived despite everything the research station has thrown at them and to whittle the list down to three or four Super Plants for the coming season.

The spring 2014 winners are varieties of torenia, buddleia and hibiscus that have outstanding characteristics.

“The (Flutterby Petite) Tutti Frutti Pink buddleia is different from the kind of buddleia normally found in local gardens, the kind that gets very large and kind of unwieldy,” Bracy said. “These stay compact, maybe 30 inches to 36 inches tall, and has a mounding habit with dark pink flower spikes standing up above the foliage. Put one in your garden now and it will attract butterflies like crazy.”

A second Super Plant, Kauai torenia, is notable not only for its pretty multicolored blooms but for its shade tolerance.

“If you have a spot in the garden that gets a little too much shade for other plants you like, try this one,” Bracy said. “It stays about 10 inches to 12 inches tall and provides eye-catching blooms all summer long. It makes a carpet of color that’s made for the shade.”

Nearly every local garden has a hibiscus of one kind or another, but the Luna hibiscus (the third 2014 spring Super Plant) has outstanding traits that make it a must-have.

“The blooms are enormous — 7 inches to 8 inches wide — and the plant doesn’t get much taller than 3 feet,” Bracy said. “It would work well in the mid-ground of a bed — not the back or front but the middle. It just loves heat and humidity.”

When the LSU AgCenter’s Super Plant testing program originated in 2009, it was intended to educate both residential and commercial growers about overlooked and new plant varieties that perform well and can add dramatically to the garden palette.

Since the first Super Plants were named in the fall of 2010, a total of 26 have been recommended (see the complete list www.lsuagcenter.com ). Every plant has been rigorously tested for a two-year time period and must perform well as far north as Shreveport and as far south as Venice.

“Some of the ones we test are old favorites that people have forgotten about, others might be something someone found in their grandmother’s garden,’” Bracy said. “We are really lucky here in Louisiana to have some great plant breeders who stay in contact with us and help us find plants to test.”

The AgCenter works with retailers and encourages them to make the Super Plant selections available at their nurseries.

Download a list of Super Plant retailers from the AgCenter web site and then get growing.

R. Stephanie Bruno can be reached at rstephaniebruno@gmail.com