As living material, our soils and composts are resilient, but proper storage helps ensure germination potential and protect against contamination. When choosing where and how to store your bagged soil or compost, consider the following:
Exposure to Light
It’s best to store bagged products out of direct sunlight. The sunlight will degrade the woven polyethylene bags over time, as well as heating and drying out the product. If bags are stored outside, try to place them to the north side of a building, but be sure that they are not under a drip edge.
Temperature
Our soils and composts are a living media. The biota in our products survive freezing temperatures, even for prolonged periods. They become active again when the soil media reaches their ideal temperature zone. It is perfectly fine for your soil to remain outside (as long as it is well covered from precipitation) or in an unheated building throughout the winter. Remember that our soil does take time to defrost. Plan on a few days or more for fully frozen sling bags to become workable. Once defrosted, it’s best to bring soil temperature to an appropriate range for best germination rates.
Storing soil in a heated building or greenhouse can cause the soil to dry out over time. While it’s possible to rehydrate the soil and achieve satisfactory results, it’s best to store your soil in a cool environment whenever possible.
Moisture
To help maintain proper moisture, please ensure that bags are adequately protected from sunlight and precipitation while stored outside. If you’re storing bags along the edge of a building, make sure that rain doesn’t drip off the roof and onto the bags. Tightly tie slings bags while not actively using them, especially if they’re in a warm greenhouse. As a result of temperature and exposure to the sun, soil generally retains more moisture over the winter than over the summer.
If soil has dried out slightly, mix wet and dry layers to achieve uniform soil moisture just prior to use. If the soil has excessively dried and appears dusty, please water to almost full saturation, and allow it to sit for 24-48 hours so that biological activity can resume. Always moisten a potting medium with warm water before using, as plants potted in a dry medium and then watered will have inconsistent moisture levels in their root zones and will take longer to establish.
Time
Storage time is a function of temperature, exposure to light, moisture retention and other factors. For optimal performance, we generally recommend a maximum storage period of 6-9 months, depending on these conditions. However, your soil may still perform adequately for up to 12 months.
Before using a soil that has been stored longer than 9 months, we suggest trialing germination rates, and we strongly discourage the use of material older than 9 months for any plantings you depend on. Old soil can be added to beds to increase organic matter and fertility.
Preventing Rodents and Other Contaminants
Occasionally, growers will find that rodents have burrowed into their soil and compost piles. While it’s almost impossible to eliminate all rodents on a farm, rodents can carry seeds into your soil. Use best practices for rodent exclusion, including storing in a closed container whenever possible, setting traps, and employing barn cats and dogs.
Likewise, we work hard to provide a product that is free of contaminants. Be conscious about keeping fluids like gasoline, diesel, and oil away from your soil. Also consider road salt contamination while transporting and storing your soil in the winter. We recommend wrapping soil, top and bottom, in a tarp when moving it in an open truck or trailer.
Finally, be sure to clean and sanitize trays and pots between uses. Pests, diseases, and weed seeds can hitch a ride between plantings on leftover soil and other debris. Using clean, sanitized trays ensures that your potting soil will perform at its best.
Some Successful Storage Examples:
- Sling bags stored along the north side of a barn, not under a drip edge, tightly tarped and brought into the greenhouse as needed in the spring
- Pallets of bagged soil stored in a unheated barn or garage, then thawed and warmed before seeding
- Bulk soil kept under a roof or well secured tarp and monitored for rodent activity
Do you have specific questions about storing our products? Email us at info@vermontcompost.com
Thank you to Speedwell Farm and Gardens and Vermont Youth Conservation Corps for their images.