Hi Ashley,

I understand about trying to garden in Champlain Valley clay! I, too, resorted to raised beds.

Regarding what to use to line your raised beds I would suggest the cardboard - either heavy weight (you can get these at places like furniture stores which receive heavy item shipments) or 2 layers of standard cardboard. Try to remove all the tape and overlap as to best block weeds coming up. Water down before you put the soil in.

My reason for having cardboard in the beds is that it will slowly break down and is not fully impermeable. This allows important soil microbes access to your beds and helps with soil quality.

However, other substrate that will remain intact longer, may better resist unwanted plant growth (aka "weeds") and grass. This would probably be a good choice for your paths (assuming you are going to lay stones or mulch down?). Something to consider is growing a low ground cover in the path areas – it makes kneeling next to the beds less painful! You would, however, first need to smoother or remove whatever vegetation is currently there. And do keep in mind that no amount of prep work will eliminate the need to weed – seeds will fall and eventually the strongest plants will likely break through; but you are right to start off with the best ‘foundation’.

Yes, you can mix soil with compost for your beds. Depending upon the nature of the compost, it might be a good idea to also ‘lighten’ the soil – peat moss, vermiculite, coco coir, etc. You can find many recipes online and I’m not aware of any good data to recommend one over another. In my quick search of ‘.edu’ references (ie: University extension services like ours), I found ratios from 1:1 topsoil to compost down to only 20-25% compost. If you know what you want to grow, you can also try to tailor your mix to its needs – soil testing of the compost and the topsoil can provide guidance.

There are sources of compost and topsoil in VT that sell by the yard directly that would be less expensive than buying from a gardening store/nursery. Some will deliver, but most are ‘pick up’ only so access to a pickup truck or seeking out someone who will do this for you is a consideration. Two that I know of are Foster’s in Middlebury and Vermont Compost Company in Montpelier (they also sell their raised bed mix by the yard for pickup) but I’d ask your neighbors (through Front Porch Forum perhaps?), local garden club, or do an online search to find more options and compare pricing.

I’m attaching a link from The University of Maine Cooperative Extension answer to a question on raised bed substrate – I’m also attaching the bulletin and fact sheet that is referenced in the link in case you want additional information.

https://extension.umaine.edu/gardening/2022/04/20/improving-the-soil-in-a-raised-bed-vegetable-garden/

Thank you sooooo much!