Hi Molly.  It's so great that you're replacing parts of your lawn with native plants.  I've been doing this myself and it's a very satisfying experience.

As to your question, let me first ask you a question--have you already obtained the plants?   If not, I recommend waiting until the early fall--late August or early September--and buying and installing them at that time.

If you already own the plants, then, yes, you can safely plant them now.  In fact, it's better to get them in the ground now rather than leave them in pots over the course of the summer.  If you keep them in pots they will be more at risk for drying out, and the roots will be compacted. 

Here is a useful link from Maryland Extension with general information about perennials, https://extension.umd.edu/resource/perennials/

Let me offer several specific tips for summer planting.

While you should get the plants in the ground as soon as you can, it's better to avoid doing so on a hot sunny day.  A cloudy day is best and worth waiting for.  If you have no choice but to plant on a sunny day, do so as late in the afternoon as possible--early evening is even better.  That will avoid the plants being stressed during their first hours in the ground.  

After you dig the hole for a plant, fill the hole with water and let it drain.  Then install the plant and water it thoroughly.  Add a generous layer of mulch to retain moisture and keep the roots cool.  After that, water the plants often, every day in dry and hot conditions.  If it you get a legitimate rain there's no need to water that day, but a light drizzle may or may not be enough--check the moisture level of the soil.  

If your plants are exposed to hot sun right after planting, they may wilt, possibly a lot. Don't panic, just keep up with the watering and they should recover.

After a couple of weeks, you can cut back the watering to every other day or every few days, but make sure the soil never dries out completely.  If you're going on vacation or traveling, ask a friend or neighbor to continue whatever level of watering is needed.  

Finally, be patient.  Plants installed in the summer may not look great their first year, and flower production may be less than normal or even non-existent.  But if properly cared for this year, they should come back great next season and you can brag to your friends about the good work you're doing for pollinators and the environment.

Best of luck.

Bob

Hi Bob,

Molly, sounds like a good plan. 

FYI, here's info from University of Maryland Extension on turfgrass removal methods, https://extension.umd.edu/resource/lawn-turfgrass-removal-methods/   Here also is info about what to plant once the turf is gone, https://extension.umd.edu/resource/lawn-alternatives/

Bob