Potting soil should be stored in its original bag within a protected container, such as a storage tote. Large rubbermaid bins, as well as repurposed dishwasher detergent containers, work great. If the original potting soil bag cannot be re-sealed, re-seal it with tape or place it into a reusable sealing bag. Be sure to label the container clearly so you can find it again when you need it.
If you plan to keep the soil for more than a few months, such as for future growing seasons, we recommend that you freeze it first. This prevents any weed seeds from germinating once the soil thaws out during the spring.
To freeze potting soil, spread it out on a plate and put the plate back in the freezer for about an hour. This process kills any weed seeds and ensures that your soil will not ice up during cold weather. When defrosting, use care not to let it get too warm; 75 degrees F is ideal. If it gets warmer than this, your soil will not dry out as quickly which could cause it to become moldy.
Mold can grow anywhere there is moisture and little oxygen, so make sure to protect your soil during winter by using one of these methods: A thick layer of mulch, pine needles, or shredded cardboard will help prevent heat from reaching the soil and may also help suppress weeds while allowing water to drain if applied carefully.
Storing Bagged and Bulk Garden Soil: If you have an excess of bagged garden soil, place it in plastic storage containers and store it in a garden shed, garage, or other dark, dry location. Avoid exposing soil to light which can cause it to lose some of its organic matter.
Soil should be stored in a clean, dry location away from any source of heat or moisture (such as windows or doors that can be opened during cold seasons). Use only as much soil as you need during each growing season and replace the soil when it becomes depleted of nutrients.
Do not reuse soil that has been used for another purpose such as planting a lawn or doing a large container plant. This soil may contain chemicals used to control weeds or insects that could be harmful if consumed by your plants.
Soil that has been shipped by courier service is usually packaged in polybags. These bags are made of petroleum-based material and should not be disposed of with regular trash. Instead they should be returned to the supplier for recycling or disposal.
Methods for Reusing Potting Soil What is the simplest method to repurpose leftover potting soil? Simply take old plants out of their containers, fluff up the dirt, and replant. If you've been reusing the same soil for several years or it's formed a white surface crust, you may need to replace it with 50% fresh potting soil and/or apply fertilizer. The key is to keep the soil loose and workable while watering new plantings so that air can reach the roots.
Soil quality can be improved by removing any dead or diseased plants or tree branches from it. All plant material should be removed as soon as you notice signs of disease or damage. Allow the soil to air-dry before adding more organic matter like compost or manure. Manure contains high levels of nitrogen which will help promote healthy root growth. You can add 15-20% manure or compost to soil as a source of nutrients and organic matter.
Soil should be added to container soils when planting out bulbs, corms, and tubers. This will help them get established quickly since they won't have access to the roots of existing plants for food. Make sure to include some sand in your bulb trays or else the bulbs will drain too much water and an unhealthy environment will develop. If using bare-root plants, fill the hole with soil and gently push the plant into it. If using transplants, place them in the hole and fill around the stem until it's just below the soil line.
Reusing Potting Soil. Reusing potting soil is typically OK if the plant you were growing in it was healthy. Even if your plants appeared to be problem-free, or if you did discover pests or illnesses, sterilize the mix before reusing it to avoid infecting next year's plants.
The best way to do this is by heating it in a 200°F (93°C) oven for 30 minutes with a few layers of newspaper or strips of tin foil placed between the pots and the heat source to prevent any burning. Allow to cool before adding to your garden.
Heating the soil will kill any diseases that may have infected the mixture as well as any weed seeds that might have been planted along with the good plants. It also helps to break up any clumps in the soil so that everything gets equal treatment when it comes time to fertilize or amend the plot.
If you want to use fresh soil instead, simply mix in enough used soil to raise the pH of your new bed to 5.5 or higher using materials such as lime or wood ash. This will help protect your plants against diseases that may have been present in the old soil.
So yes, you can reuse potting soil if you're planning to repot or transplant your plants and want to minimize costs. But be sure to sterilize the mix first to avoid spreading diseases.
Potting soil does not need to be changed on a yearly basis. However, the soil must be treated to provide proper drainage and enough nitrogen levels. Old potting soil frequently becomes compacted and shrinks away from the container's sides. This stops the soil from adequately draining. It also can cause root damage if the roots are forced to bend too far to reach water or nutrients.
Outside temperatures have an effect on how often you should replace your soil. If the temperature stays below 50 degrees F for several months, you will not need to add more soil when planting in the spring. Summer heat and frost can decompose organic material in the soil, causing it to become acidic. Unless you are growing plants that like acid soil, you should add more base (such as wood ash or lime) to make up for any lost alkalinity.
If you want your plants to grow quickly, get large flowers or fill containers fully, you will need to add more soil when re-potting in the spring. The amount you add depends on how much space you plan to give each plant. When filling larger pots, it is best to add a small amount of soil and pack it in firmly so there are no air pockets to disturb growth.
As long as you do not over-water or under-water your plants, you do not need to change the soil too frequently.