I would say to plant what you can and will use if the space is small.* If you use herbs in cooking, those would be my first choice.* I plant extra of some herbs that we use in cooking for butterfly larval food and plant others just for the caterpillars.* Here in Maryland the black swallowtail butterfly caterpillars (cats) love my fennel.* I also plant extra parsley so they can have some and I can too.*** Some years I use parsley to edge my flower beds.* Some herbs will be perennial in your hardiness zone.* Here's some sites about herbs.
Here's a Canadian site about butterflies.* At this site at the bottom of the page, it says, " Plant suggestions are provided below for four Canadian regions...", but the links are actually on the left.* Oh, and if you click around at this site, beware that you may find their recording of a frog!* Two of my 60 pound dogs jumped on me to find the frog, and that's quite an awakening if you're a bit sleepy at the 'controls'.* :shock: :shock: :shock:
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.