One of the most common questions we receive at Royal City Nursery is ‘What fertilizer should I be using? The answer, however, is not a one-size-fits-all. Whether you’re tending to lawns, trees, shrubs, flowers, vegetables, or fruit trees, each plant has its own unique needs when it comes to fertilization. Tanya Olsen, third-generation owner of Royal City Nursery and a Professor in the Horticulture program at Humber College, breaks down the different types of fertilizers you can use. She also explains the all-important three numbers you see on the product and what this actually means for you and your plants.
Watch our latest video on youtube to learn more or scroll to continue reading.
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Types of Fertilizers
Granular Fertilizers: Granular fertilizer is applied to the surface and typically lasts anywhere from 4 to 8 weeks, with a 6-week average. Some hanging basket-specific granules can last for up to three months. Every time it rains or you water your plants, the prill, the individual granule or bead, dissolves and releases nutrients into the soil, providing a steady supply of fertilizer over time. This method is ideal for spring and fall months in the garden, or during the growing season for plants in containers.
Liquid Fertilizers: Liquid fertilizer is added to water, allowing the plants to immediately absorb the nutrients. It’s fast-acting and suitable for long term use with containers, vegetables and annuals as well as a ‘pick me up’ for trees and shrubs in the spring. The same is also true for powdered fertilizer you mix with water. Liquid fertilizers are best used in spring and early summer, from April to mid-July, when plants are actively growing and need a quick nutrient boost.
Understanding the Three Numbers
All fertilizers come with three numbers on the package, such as 4-10-2. These numbers represent the percentage of three macronutrients: nitrogen (N), phosphorus (P), and potassium (K), in that order. An easy way to remember what they mean is to think of them as “up, down and all around”.
Remember: Up – Down – All Around
When choosing a fertilizer, consider what you want your plant to achieve. For example, for trees and shrubs in the spring, use a fertilizer with a higher middle number (phosphorus) to encourage root growth, which in turn supports overall plant health and growth.
Lawn Fertilizer
For your lawn, consider a couple steps depending on the season. Using Fafard’s Lawn Program, in the spring, use step 1 and 2, which are higher in nitrogen (7-2-3) to promote overall green of the leaf. In the fall, switch to step 3, which is higher in potash (4-2-9) to support plant health as it becomes dormant. Fall fertilizers generally contain less nitrogen, as plants need to focus on overall health during dormancy.
Our experts are always happy to help you pick out the perfect fertilizer for your plants! Come in-store and chat with our team. We look forward to seeing you. Happy planting!
About Tanya Olsen:
Tanya is a third-generation garden centre owner and landscape designer.
Teaches Horticulture Apprenticeship at Humber College in Ontario, Canada.
Has a weekly segment on CTV news.
Has a Bachelor of Landscape Architecture.
YWCA Woman of Distinction.
About Royal City Nursery:
Guelph, Ontario’s only third-generation, full-service garden centre! We specialize in creating custom outdoor living spaces and unique solutions for all your garden, landscape, and seasonal decorating needs! At our new greenhouse, located between Guelph and Cambridge, we are the garden centre of choice for discerning homeowners, landscapers, and designers.
