Compost is often referred to as “black gold” because of its rich colour that radiates nutrients and the energy boost that it provides to support soil life

Though it would seem that spring is the right time to give your garden a boost, compost needs a little time settling into its new home, so the optimal time to give your garden that shot of nutrients is right before winter.

How compost works for your garden

Food for the soil: Soil is home to a rich ecosystem of organisms, and the top few inches are just teeming with life. In order to keep these beneficial microbes thriving, we have to mimic nature’s recycling strategy by adding in organic debris. Compost is decomposed organic matter that has stabilized, yet continues to decompose at a slower rate once it’s on your garden bed. Adding compost (aka organic decomposed matter) invites earthworms, insects and other microorganisms for a little snack. They repay you by keeping your soil healthy.

Nutrients for the plants: Adding compost to your garden before planting is essential to how well your plants will do. Compost contains nutrients like potassium, nitrogen and phosphorous, as well as micronutrients like manganese, zinc, cobalt, iodine, iron, copper and boron. This garden bed “superfood” will release these nutrients into the soil, which will later be absorbed by plants, eventually enriching our garden veggies come spring.

Water retention for all: Compost increases the water retention capacity of your soil. Soil that’s rich in organic matter works like a sponge and holds onto water so that plants have lower watering needs (which means you water less). If you have sandy soils, compost will improve your soil structure as sandy soils are known for poor water retention.

Clay soils, however, have good water retention capacity, but the soils can fill up quickly with water and exclude oxygen and nutrients, which will eventually drown the plants. This is known as water saturation, and can also cause soil runoff because the soil doesn’t have the capacity to hold onto more water. Adding compost in this case will aerate the clay soil, increasing its capacity to hold onto water, oxygen and nutrients needed for healthy plant growth.

Why autumn?

frost on leavesPhoto by Lukasz Szmigiel on UnsplashIn the winter, soils are often left bare until we’re ready to plant our spring gardens, but this leaves us with nutrient-depleted soils and more weeds come spring. Bare soils also lead to compaction, and tight soil conditions make it challenging for organisms to survive. Adding compost and organic debris before winter will provide a hospitable environment for organisms, and those microbes will repay us with keeping the soil functioning at its best all winter long.

Incorporating the compost before the first frost in late fall allows it to break down slowly and to be worked into the soil. Because compost is still continuing its natural process of decomposition, the winter allows it the time to continue this natural process. The nutrients aren’t always available for plants right away; adding compost directly before planting can tie up the nitrogen that the plants need, so this winter period allows the soil food web to continue working on unlocking the nutrients for plants once the warmer season arrives. If you’re also planning on adding compost to your garden in the early spring, be sure to give it about two weeks to settle into the soil before planting into it.   

Adding compost before winter is a game changer. On top of being an amazing support for plants’ root systems during dormant season and providing soil with the energy to withstand the colder temperatures, you’ll notice the difference in water retention, weed reduction and overall plant growth next growing season.