Do something about your lawn. Raise the lawn mower blade an inch; mowing high this time of year gives the grass roots a little shade, and keeps the ground from drying out too fast in the heat. It also shades out weed seeds, keeping late-season emerging seeds from being triggered by sunlight. Lawns are also especially aggravated by dog pee in the summer, so if you have a place that your canine friends prefer, make sure it stays watered to dilute the nitrogen in the urine before it burns your grass. If there's enough traffic to actually kill the grass, find ways to divert the dog walkers, add compost, and reseed as soon as we get a week of cooler weather.
Learn about butterflies. There's actually an official day to learn about butterflies — March 14 — but I didn't know about it until today (and I'm betting you didn't either), so let's celebrate it now. The first monarchs are starting to show up in Philadelphia, which means a third generation has happened along the journey from Mexico, where they overwinter. They're attracted by many different flowers but will lay their eggs only on plants in the milkweed family. It's not too late to plant a few more of these, and while you're planting, put in seeds for more dill and fennel, as these are favorites for the young of swallowtail butterflies. They still have time to push out another generation or two this summer.
Do some maintenance on your birdbath. Be sure to change your water on a regular basis so that mosquito larvae don't live in it. Try moving it to a shady space, so the water doesn't get too hot. And scrub it out once in a while, using a handful of something rough, like dry grass clippings or sand, to keep algae from growing.