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  • Naomi Stephens | Permaculture Designer

Filling Gaps in Your Raised Bed: Ensuring Healthy Soil on Concrete



As city dwellers, we often find ourselves craving for a deeper connection to nature. However, when it comes to gardening, limited space and the lack of access to soil can often make it difficult for us to flex our green thumbs. This is where raised bed gardening comes in handy, allowing us to grow vegetables and herbs even in small spaces with limited earth access, such as patios and balconies. However, when you're gardening on concrete, it's no secret that the lack of access to soil can be a challenging hurdle. But with the right techniques, filling gaps in your raised bed can guarantee an abundance of healthy soil for your plants to thrive.







Start with a quality soil mix


Filling gaps in your raised bed involves preparing your soil mix with a high-quality soil mixture. A soil mixture that includes a combination of organic material such as compost, worm castings, and peat moss, with minerals such as perlite, vermiculite, and sand, will ensure that your plants have everything they need to grow healthy roots and stems. Using a quality soil mix will also save you a lot of money in the long term as your plants will be healthier, requiring less attention and fewer fertilisers.


Compost your kitchen waste


Composting is an excellent way of adding nutrients to your soil and reducing the amount of organic material going to the landfill. You can easily compost your kitchen waste by setting up a compost bin in your balcony or garden. Coffee grounds, fruit and vegetable scraps, and eggshells are all good sources of compost. After the compost has matured, add it to your soil mix to enrich the soil and improve the structure of your raised bed.


Use a cover crop


Cover crops are excellent at filling gaps in your raised bed. They not only add nutrients to the soil but also prevent soil erosion, suppress weeds, and improve water retention. Some examples of cover crops you can use include clover, rye, and buckwheat. Once the cover crop has matured, it can be mowed and tilled into the soil to further improve the soil quality.


Mulch your soil


Mulching is an excellent way of preventing soil erosion, conserving moisture, and suppressing weed growth. Mulch also adds organic matter to the soil, which enhances the soil structure and fertility. You can use a variety of mulching materials, including straw, wood chips, and shredded leaves. Apply a 2-3 inch layer of mulch on top of your soil, making sure to keep it away from the plant stems.


Choose the right plants


Finally, selecting the right plants can make all the difference in ensuring your raised bed has healthy soil. A common mistake city gardeners make is planting a variety of plants with different needs for soil types and nutrients. As much as possible, it is best to select plants that have similar nutrient requirements so that they thrive together without competing. Additionally, selecting plants that are well suited to the soil types in your area can also ensure better growth.



With these tips, filling gaps in your raised bed on concrete need not be a daunting endeavour. A little bit of planning and effort can go a long way in creating a healthy and thriving garden in even the smallest of spaces. Just remember to start with a quality soil mix, compost your kitchen waste, use a cover crop, mulch your soil, and choose the right plants for your raised bed garden. With these techniques, you can grow an abundance of fresh vegetables and herbs, and connect to nature in the comfort of your own home.



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