The Simple Way To Replenish Container Soil Before Summer – So You Can Keep Reusing It For Years

As the growing season fast approaches, you may be wondering if the soil in your containers will suffice for another year. With a limited amount of resources, container plants are notorious for quickly depleting whatever goodness is in the soil and can struggle as a result.

In urban environments or for those without beds or borders, container gardening can be a great way to grow. From patios and terraces to balconies, containers are ideal for smaller spaces and can even be taken with you when it is time to move.

Over my career, managing community, kitchen and commercial gardens, I have cared for numerous pots and planters filled with edibles and ornamentals. Read on to discover the best way to replenish container soil to support your plant's future growth and save time and money.

Why Replenish Container Soil

At this time of year, many of us will be looking at our containers and wondering if we can get away without replacing all of the compost, a costly and time-consuming process for those of us with lots of pots and planters.

Unlike plants grown directly in the ground, those grown in containers only have a limited amount of soil and nutrients available to support their growth. With the goodness and nutrients often being used up within a matter of weeks or months, replenishing container soil is key to keeping pot-grown plants healthy and vigorous.

Certain plants use up the soil’s fertility more quickly than others. For example, roses and tomatoes are considered hungry specimens and can use up nutrients far faster than slower-growing trees and shrubs, which might only need their soil replenished every couple of years between being re-potted.

Step 1: Top Dress Containers

Depending on how quickly they grow, plants generally need repotting every 3 to 5 years to give them more space.

For the years in between, refreshing some of the soil will help provide the plant with the nutrients it needs to thrive. To do this, remove the top few inches of soil from the planter or pot. This can either be replaced with a suitable new potting mix, such as Miracle-Gro potting mix available from Walmart, or reused once fortified.

If you opt to reuse the container soil, remove any roots that might be present and add a similar quantity of nutrient-rich organic matter, such as garden compost or well-rotted manure, and mix thoroughly.

Leaf mold can also be used, but it is considered lower in nutrients. You can then use this refreshed mix to top up the container and give the plants a boost.

Step 2: Add Extra Nutrients

Along with many others, the main plant nutrients needed to support growth include nitrogen (N), phosphorus (P), and potassium (K), which sustain leaf growth, root development, and flowering and fruiting.

You can help provide these key nutrients through top dressing or repotting with fresh compost, but for less-hungry plants, you may be able to add a slow-release fertilizer or a DIY fertilizer instead.

You can use organic or inorganic fertilizers, but whichever type you choose, you will want to provide the right nutrients for the plants.

For example, chicken manure pellets such as Espoma organic chicken manure available from Amazon, support leafy growth as they contain high levels of nitrogen, whereas Muriate of Potash from Amazon delivers high levels of potassium, used to encourage flowering and fruiting.

For hungry specimens, it can be best to not only refresh the top few inches of soil but also to incorporate a slow-release fertilizer, which will help feed the plants over the coming months.

However, depending on what you are growing, the above methods may not be enough, and further fertilizing using a water-soluble feed over the summer months may be required to support ongoing flowering or fruiting.

Reusing Container Soil

If you have many containers, the amount of spent container soil left over after repotting and topdressing can be considerable. To reduce waste and keep your garden as sustainable as possible, you can use it rather than take it to the garbage dump.

You can use it to mulch borders, top up raised beds, and even add it to your compost pile.

You can also add any surplus soil from old containers to your compost bin. Even though depleted, it will still contain organisms that will help break down food and garden waste.

To avoid overwhelming the current compost heap and its brown-to-green waste ratio, you may need to add it in layers slowly over time. If you do not have a home composting system, you can start with a DIY system or purchase one such as this Efurden 45-gallon compost tumbler available from Walmart.

However, it is important to only reuse soil from healthy plants. Do not reuse any soil from waterlogged, root-rotted, or otherwise diseased container plants, as this may contaminate future plants.

Growing certain plants and crops in the same soil year after year can lead to nutrient depletion, pests, and diseases. To prevent this, you should avoid growing the same plants in the same spot year after year and instead follow a crop rotation.

Along with the soil’s fertility, soil health is key to supporting healthy plant growth. Encompassing its structure, pH, beneficial organisms, and organic matter levels, soil health can be a good indicator of your natural environment and its ability to support wildlife and sequester carbon dioxide.

Furthermore, research has shown that getting our hands in healthy soil can be good for our mental health as well.

You can boost your soil’s health through several methods, including avoiding compaction and practicing no-dig methods, but incorporating organic matter is perhaps the most beneficial.