Fertilizer from a friend –


Hi! A friend gave me a container of 10-52-10 by BioFert. I don’t know much about fertilizer. I have added worm castings and cow manure. Should I use this other fertilizer? I’ve read it’s too strong and could kill plants?? Any suggestions? And if it’s ok to use, what ratio of fertilizer to water would you suggest? Thanks so much!! Stay safe :)


Good on you for using (well-rotted) cow manure and worm castings!

We at Toronto Master Gardeners are big fans of using organic materials to amend your soil, such as the cow manure and the worm castings (vermicompost) you mention, as well as other types of compost (mushroom, shrimp etc.), leaf mould, and mulches such as bark or shredded leaves.

Organic materials have more benefits than just providing the three main nutrients listed on most commercially-available fertilizers, whether synthetic or organically-based.  Those three nutrients (N-P-K) are nitrogen (1st number; promotes leafy growth); phosphorous (2nd number; promotes flowers and fruit); and potassium (3rd number; promotes root development).  In addition to providing N-P-K, organic materials have other trace elements and minerals, and they make your soil lighter and fluffier, which enables roots to take up water and nutrients more readily.  They promote moist well-drained soil, which is a requirement for many plants.  They also provide the right nutrients in small amounts at the right time, when a plant is ready for them.

Below is an article written in partnership with the City of Toronto on the benefits of using organic amendments.  Note that although the article mentions digging amendments into your soil, you can also place these directly on top of your soil and around plants (but not directly touching plant stems to avoid burning them).  The amendments will naturally decay, and earthworms and insects will also go to work, carrying the material down into the soil and loosening it.  Unnecessary digging can sometimes bring up undesirable dormant weed seeds to the surface, and it can disturb the web of beneficial fungal mycorrhizae that live under the soil surface at the root level.


Too much fertilizer can have a detrimental impact as it can burn tender roots and inhibit the plants’ ability to take up nutrients and moisture from the soil.  The BioFert 10-52-10 is likely meant to be a plant starter fertilizer for flowering plants at time of transplanting, as the nutrient numbers are quite high.  If you do decide to use it, either for its intended purpose or as an all-purpose fertilizer (for instance to provide an occasional boost in spring and/or midsummer to flowering plants that are heavy feeders such as roses or clematis), you will want to double or triple the amount of water suggested on the package directions, so that the fertilizer is at half-strength or one-third strength.  Use sparingly (0.25 litres to 1 litre, depending on size of plant).  Do not use it after mid-summer, as it could cause the plant to produce too much tender new growth that may get killed by early fall frosts.

Happy gardening.