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Plants for north side of houses include hydrangea, bleeding heart, hosta, lenten rose, caladium, Campanula poscharskyana, Geranium spp, Pulmonaria, Brunnera, astilbe, ferns, Liriope, wild ginger, jacobs ladder, bee balm, etc. All the seed and plant online retailers have lists of plants that do well in shade and clay. Or, just search for shade plants in zone 5. Avoid plants said to need well-drained or freely-draining soil. Clay is fertile and moisture retentive but brick hard if allowed to dry out. Be sure to use at least 2 inches of mulch and nest a couple inches of compost under each plant.

Sun, shade, dry or wet area? These are all important things to know when choosing any plant. If the area gets sun, a creeping (horizontal) juniper, pussytoes, sedum and creeping thyme are nice. For shade, consider ferns, solomon's seal, bearberry and epimedium. There are many, many more! Here is a website to give you ideas but check nurseries near where you live. Buying local in the case of plants means you are getting a plant accustomed to your weather conditions. https://www.bluestoneperennials.com/groundcovers.html?ext_title=All%20Ground%20Covers

We need more info to give you sound advice. Please repost, or add to this one, with your location, type of soil in the area and whether you seek to grow shrubs, perennials or annuals. Does the area get filtered sunlight, morning or evening direct light or would you characterize the area as deep shade? thank you

This article may have some possible plant choices for your experiment.

https://www.gardeningknowhow.com/ornamental/flowers/fgen/winter-sowing-flower-seeds.htm

If you get get any plant from a local nursery, then they will be able to direct you on water requirements, but most native nurseries will sell plants that are adapted for your environment. This link will help you find you local extension service: https://www.gardeningknowhow.com/extension-search/

This will depend on your area, and climate zone. I will include an article for plants that do well in these situations: https://www.gardeningknowhow.com/special/slope-hill/plants-that-grow-on-slopes.htm