[Kajazy]

My clayey soil has, unsurprisingly, baked hard in the recent dry weather following the rains. Should I be doing something to break it up? Will it hinder my plants' growth?

[Trillium]

It has formed a hard crust that will cause any rain/water to simply run off rather than soak in.

Best to get the hoe out and pretend you're weeding to break up the crust everywhere. this will both let in more air plus let any rain soak in easily. Once you hoe up the soil, some mulch would be a good idea to keep the crust from reforming and to trap in any moisture. Use whatever you can get - straw, leaves, compost, old grass clippings, etc.  If you do nothing, then the dryness will stress the plants which will attract more pests.

[Kajazy]

Ok - thanks for that. I'll do a general hoe around, then water those plants that need watering and mulch those straight after that. I'll wait for (hopefully) the rain later this week and then do a general mulch around.