Hard Work makes the Dream Work
Don't look at me like that. Maintenance is an important part of the process and employing good maintenance practices in the beginning will make it easier for your plants to thrive and will require less effort for you down the road. And, good news for you, native perennial gardens are already relatively low-maintenance!
Mulch Ado About Nothing
Apply a 1" layer of mulch in the spring. You can probably get mulch at your local yard waste facility. Or it can be made right in your yard by composting leaves, food waste, and shredded wood material. Spread the mulch evenly across the beds, but stay away from the stems of the plants to prevent rot and keep good air circulation. Once the plants are grown together and generating their own leaf litter, you'll probably be able to mulch less frequently or not at all.
Lost in the Weeds
The best way to get rid of weeds is to yank them out. A layer of spring mulch can help to suppress any unwanted plant pests as well. Don't use herbicides!
Taking Care of Your Native Buddies
This basically means cutting off flower heads after they're done blooming. It's not absolutely crucial to do this but it can prolong the bloom because it prevents the flowers from going to seed. This also controls the spread of flowers that self-seed. However, some birds enjoy eating the seeds in the winter.
Staking & Cutting Back
Some plants will grow so tall that they start to flop over. Tying them up with twine and a wooden pole can keep them looking perky and prevent them from shading other plants.
To keep taller-growing perennials a little shorter, you can also cut them in half in early spring, stunting their growth.
Winter is Coming
Before winter comes, there is some optional garden maintenance you can do. One thing is to trim back all the the dead flower stalks. If you want to keep them for winter interest, go right ahead. This will also provide food and nesting material for winter birds and mammals. At the end of winter, you can also cut back any grasses.
More on Maintenance
Below are a list of sources that you can use to find more detailed information about keeping your native garden maintained and happy.
Missouri Botanical Garden
Edge of the Woods Native Plant Nursery