Excessive heat triggers need for vigilant watering of first-year native plants

Editor’s note: Johnson’s Nursery has partnered with SOS Save Our Songbirds to donate native plants for events and other learning opportunities in 2023. We are grateful for their support and their expertise, shared in this blog post.

MENOMONEE FALLS – Wisconsin’s drought and the heat dome that’s been making life miserable in the southern U.S. for the last month is expanding and bringing excessive heat warnings to much of Wisconsin through the end of July.

That forecast makes it doubly important to water first-year native plants to keep them and the wildlife that depend on them healthy, native plant experts say.

“In the heat of the summer like this, it's really hard to over water,” says Ben French, vice president of propagation and product development for Johnson’s Nursery in Menomonee Falls. He’s been growing plants for Johnson’s Nursery for more than a decade.

“Plants are ectothermic and depend on the outside heat to grow. Once installed, as long as you can water them to their needs, then they'll establish even quicker and grow even faster.”

He advises checking plants every day during particularly hot stretches of weather, noting that every plant has its own specific water needs that differ by species, how long the plant was growing in the container before it was planted in the ground, and the outside weather.

 “The more often you can check, the better job you can do,” he says. “Sometimes that's not realistic for a company or if it's a very large planting, but the more you can watch them, the more you can see what they need. The plants will tell you if they're a little bit thirsty.”

Thirsty plants will start losing water pressure inside of its stems, and the leaves will start to tilt and wilt. “The plant is going to start going backwards at that point,” French says. “And what you don't want to happen is have the plant reach permanent wilting point, which means it's going to droop to where it can't refill itself up with water.”

A native prairie plant purchased in a one-gallon container and planted in the dirt could use a whole gallon of water every day during these particularly hot and humid days, French says. See their explainer on nursery stock sizes.

 French notes that exceptions to watering every day include woodland ephemeral plants, like a Trillium, Bloodroot or Jack-in-the-Pulpit. “They need very little water at this time of the year. They just have to not dry out completely,” he says.

Bare root plants have roughly the same watering guidelines as plants grown in a container and then transferred into dirt.

Find more guidance on watering on Johnson’s Nursery Water Your Plants webpage.

Second year-plants need little outside watering

The good news is watering needs decrease significantly after the first growing season, and that’s one of the many benefits of planting native plant species that have evolved in the same geographic area where they’re planted.

“I would say most plants, if you do a fair job their first growing season in the ground, you'll probably only have to water them that first season and the next season, they should be good.”

French says people may also have to watch and water native plants in their second growing season under certain conditions --“if it's a plant that's a little bit slow, a little bit root bound, or you got it in at the wrong time of the year, or you picked a really hard spot for it to grow.”