Resources

Fall Soil Preparation

Amend your Garden Soils in the Fall for more Beauty Next Year
The growing medium is critically important for the health of your plant materials. Soil structure is as important as its fertility. Fall is a wonderful time to amend your garden soils for several reasons.

1. The soils are generally much drier than in the spring. One should never till or turn wet soils as it created compaction and has just defeated your purpose of lightening and aerating the soil.
2. Fall is also preferable for soil prep as you can see where all of the perennials are growing. In the spring, hostas, lilium, perennial hibiscus all emerge late and you risk digging them up.
3. Typically there is time in between the first frost/closing down the garden & when the ground is frozen. There are not a lot of other garden chores to tackle at "down time" before winter mulch is applied.
4. Lastly, the spring is so busy with all kinds of other chores, that if you can get something out of the way I would advise doing so.

Soil Testing & Quality
Taking a soil test 5 to 10 days before your garden reclamation is suggested to ensure your county extension agents have adequate time to process your request so that you can make appropriate amendments to your soils. The University of MN provides this service for $15 each test. To take a soil test you need to scrape off the top soil, dig out three different cores of soil 4" to 8” deep from the same bed, mix them together and place in the soil test bag.

Besides the three basic elements Nitrogen (N), Phosphorous (P) and Potassium (K) attention should also be paid to the many micronutrients and mycorrhizae required in a healthy garden. Mycorrhizae are a group of fungi that has a symbiotic relationship with plant roots. Mycorrhizae increase plant roots' ability to extract water from soil. The surest way to kill off many of these beneficial trace nutrients is to apply an herbicide (like preen) which basically cooks the soil. An herbicide can be recommended for extremely weedy gardens at first, but then to guarantee a healthy gardens’ return, a more organic approach is suggested.

Just as important as the nutritional value or pH of a garden, is the soil structure. Heavy clay soils have difficulty supporting even the hardiest of plant life. Optimum is a loamy garden soil that sustains nutrients while providing adequate drainage. For more information on soil science, go to: http://cru.cahe.wsu.edu/CEPublications/eb1633/eb1633.html.

Digging Steps
First we dig out any plant materials in the garden and place them on a tarp out of the sun, and then we look at the edge of the bed. If you have a fabricated edge (plastic, brick, paver, etc) this is the perfect time to re-lay that edging if it has been damaged by the lawn mower, heaved, and settled or if you wish to change the lines of the bed. We use spray paint (or lay a garden hose) to identify where we would like the new border of the garden. No matter what kind of edging will be going back in, we use a flat edging shovel to create a clean line at a 90 degree angle in between the soil of the garden bed and the turf, patio, sidewalk or whatever is on the other side.

Fall Soil Preparation
Sometimes amending the existing soil by simply turning in compost or manure is sufficient. We use a shovel or spading fork to flip the soil and break up the clumps. The old English method of double digging works beautifully but can take a lot of time and energy. We feel using a rototiller fractures the soil and breaks down all of the soils’ structure and should be avoided.

However, many times, where there is new construction, or in heavy clay soils, adding amendments is not enough and it is advised to excavate garden soils to a depth of 12" to 24” and begin again. To make sure that you have not created a bath tub effect after the excavation where the remaining soils do not interface with the added soils, we suggest mixing in a clay conditioner into the bottom of the excavated hole. Then compost, manure, pine bark or garden soil mix (which is parts compost, peat, sand, and soil) can be added. Never add straight sand to help with drainage. Remember sand plus clay makes cement. If soil does become compacted from working it when it is wet, Mother Nature will straighten it our again over one freeze-thaw cycle. By the time goes through the winter and then thaws, it should be lighter again. This would also be the perfect time to empty your compost bin into your borders & amend their soil with your own home grown compost! This works well now also as it clean out your compost for the winter so you have plenty of room to put your kitchen scraps in it all winter long.

Landscape Fabric
We suggest that no landscape fabric is laid down in either perennial or shrub borders. While this barrier helps to keep weeds down for the first several years, after that, weeds simply grow on top of the fabric so very quickly the one benefit no longer exists. More importantly, while manufacturers suggest that air, water and light can all penetrate through to bring moisture and nutrients to the plants, the reality is that landscape fabric does not allow the plants basic needs to reach its roots. Many times the roots grow into the fabric and not down into the earth. The plant also will only grow as large as the hole cut in the fabric for it. Landscape fabric helps for the short term, but does not promote sustainability in the garden.

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