​Oenothera gaura, Biennial Gaura or Biennial Beeblossom

This species made it onto my seed wish list due to a species-by-species read through of the Evening Primrose genus on VASCAN in an effort to figure out the correct species name of the Sundrops growing in a lot of older gardens and often offered at community plant swaps. You can find that whole story here https://www.facebook.com/ACultivatedArt/posts/pfbid038JieFHGsQ7u8y7CtWzvRFYK63Rd2QFBhHxJyZnVZZVYDJjcBkaYnwBDbkmuvUch6l

While working down the 15 Oenothera species growing in Ontario (6 are introduced) I came across Oenothera Gaura. Gaura? Like, Butterfly Garua, the short-lived, tender perennial that blooms all summer with delicate pink and white flowers? That Gaura? Not exactly, the Butterfly Gaura sold in garden centers is Oenothera lindheimeri and is native from Louisiana to Texas.

Oenothera gaura is a biennial species, spending their first growing season growing a large, ground hugging rosette of leaves that is almost identical to Common Evening-Primrose (Oenothera biennis). The similarity in their appearance continues into the early part of their second year, as they start sending up tall, green stems with narrow, pointed leaves that seem to be considered tasty by a range of small critters. Where their difference begins to become apparent is at the start of flower bud set. Biennial Gaura have finer, more elongated blooming stems and reddish buds that open to the airy, pink to white blooms that bob lightly in the breeze, the trait that I suspect leads to their other Gaura cousins so often being compared with clouds of butterflies.

From that ground hugging rosette, they stretch to over 6’ in height by the end of August, when their first blooms begin to open. They continued flowering until the first frost in mid October, making them a lovely addition to the fall bloom season.

Unlike their Common Evening Primrose relatives, they develop a single large, hard seed from each flower, rather than a pod full small, hard grains the size of poppyseeds. When it comes to gathering them, they actually come loose from their supporting stems before completely drying or browning. I learned to gently grasp the stem and pull it through my hand to knock free any loose seeds as a way of gathering them before they fell on their own. I am sure that quite a few dropped between gatherings and that the finches consumed many more but I still ended up with plenty for growing and sharing. They are generous in their seed setting.

While it looked by late fall that most of the plants had done the biennial thing of exhausting their store of resources to grow as many seeds as possible, a couple of plants had a smaller, offset rosette coming along at their base so I hope to have a few blooms again next year, while the next generation is growing their rosette of leaves for the following season.

These are an incredibly lovely, if short-lived, species to include in any sunny, average-to-dry garden. A few other tall species that could thrive alongside them include Big Bluestem, Giant Purple Hyssop, Tall Tickseed, the late blooming strain of Wild Bergamot, Compass Plant, Prairie Dock, Stiff Leaved Goldenrod, Missouri Ironweed and, of course, Common Evening-Primrose.