A successful garden planting begins with proper site preparation. Removing competing weeds and grasses from the planting site preserves soil nutrients and moisture for desired plants to utilize. When choosing a method please take into consideration how long you have before planting
Mechanical:
-Digging. Using a sod stripper or a shovel, remove sod and other shallow root plant material. Deeper rooted plants can be dug out with a trowel or shovel as needed. Disturb as little soil as possible because seeds, that are lying dormant in the soil, will be exposed and germinate. Once the area is clear of competition, rake the site smooth and cover with 3 inches of mulch. This method is very labor intensive, but can be planted immediately and works quite well.
-Tilling. Using a rototiller, turn the top 2 inches of soil over and let the plot rest. Tilling deeper than 2 inches can expose unwanted seeds and disturb the water transfer system in place in the soil. For best results we recommend 3 tillings to be completed in the spring, summer and fall. The plot can be planted after the fall tilling.
Covering:
With these methods the area is covered for at least one month, but ideally a full season.
-Cardboard. Cover the area with 2+ layers of cardboard, tape removed. Overlap sections to be sure weeds don’t grow in between pieces. Cover with mulch or topsoil to weigh down the cardboard. The earliest you can start planting is after one month but leaving it for at least one season is ideal.
-Black plastic. Cover the area with black plastic weighed down with rocks or bricks. Leave the area for at least one season before planting. Though this is a pretty hands-off method, it is good to check on it periodically to be sure the plastic is still solid. If it begins to break apart, remove it and recover with new plastic.
Herbicide Spray:
-Organic sprays. These usually contain acetic acid, citric acid, essential oils and sulphates. Please refer to the label for concentrations and repetitions needed for that specific product. Organic sprays are more effective on plants less than 4 inches tall; therefore, these are usually more effective when used together with a mechanical removal.
-Chemical sprays. A general-purpose herbicide like Glyphosate will kill both broadleaf and grass species. A 3% solution of glyphosate should be applied 2–3 weeks prior to planting.
Caution should be used in application to avoid drift and creating off target damage. It is also important that you read the label on the product you are using for active ingredients and product use. Many big box and hardware stores offer products that have additional ingredients added to the mix to extend the activity period of the product. Many of these additives have negative impacts on plants you are installing. Use products that only contain glyphosate for your project. Once the vegetation has turned brown it is safe to rake out the litter or plant right into it.
Mechanical and Herbicide:
This process may take longer but is the most effective for weed control. Remove vegetation from the planting site with a shovel then rake smooth and allow the site to green up (about two weeks). Once the new growth is about one inch tall spray with an herbicide spray. After 2-3 weeks the area is safe for planting.
Once prepared
Once the area is prepared using your desired method(s), if there is any time delay until planting, cover the area with 3 inches of mulch to prevent any further weed development. The best mulch to use is double ground red pine bark. If double ground isn’t available, then any red pine bark is fine.
Here are a few video tutorials:
Michigan Wildflower Farm Site Preparation
Prepping a Difficult Site: Killing plants that refuse to die