The robust health and rapid growth of nursery plants stem from professional feeding techniques designed for maximum efficiency and precise nutrient delivery. Commercial nurseries use specialized products and application methods to ensure consistent, optimal growth throughout the production cycle. This system relies on fertilizers designed for prolonged, predictable release, supplemented by quick-acting liquid feeds for immediate needs.
Controlled-Release Fertilizers
The backbone of modern commercial nursery nutrition is the use of controlled-release fertilizers (CRFs), which are granular products encapsulated in a polymer or resin coating. These coated pellets contain a precise blend of nutrients, including nitrogen, phosphorus, and potassium, protected from immediate dissolution. The coating acts as a semi-permeable membrane that regulates the rate at which water enters the pellet and dissolves the nutrients inside.
Once water penetrates the coating, the dissolved nutrients slowly diffuse into the potting media, providing a steady supply to the plant roots over an extended period. The release rate is primarily controlled by the thickness of the polymer coating and the ambient temperature of the growing media. Higher temperatures increase nutrient diffusion, while lower temperatures slow it down, matching the plant’s metabolic demands.
Nurseries choose CRFs based on their longevity rating, which indicates the expected release duration, typically ranging from three to 14 months. Growers select a product that aligns with the time the plant is expected to remain in the container before sale. Applying the fertilizer once at the start of the production cycle drastically reduces labor costs associated with repeated feeding.
Supplemental and Liquid Feeding
While controlled-release fertilizers provide foundational, long-term nutrition, nurseries frequently employ water-soluble or liquid feeds to address specific, short-term requirements. These supplemental feeds dissolve instantly in water, making nutrients immediately available to the plant roots. This rapid availability is ideal for correcting immediate nutrient deficiencies.
Liquid feeding is also standard practice for delicate young plants, such as fresh cuttings or seedlings, which have not yet been transplanted into media containing CRFs. These propagules require a gentle, readily available nutrient solution to support initial root and shoot development.
Specialized granular fertilizers are sometimes used to make precise adjustments to the potting media itself, rather than just feeding the plant. For instance, dolomitic lime is a common amendment added to soilless media to increase the pH level and supply calcium and magnesium. This helps maintain the overall chemical balance necessary for optimal nutrient uptake.
Application Methods and Scheduling
Professional nurseries utilize several highly efficient methods to apply these specialized fertilizers, integrating the process directly into their production workflow. The most efficient method for controlled-release fertilizers is incorporation, where CRF granules are uniformly mixed directly into the potting media before potting. This ensures the fertilizer is distributed throughout the root zone, minimizing nutrient loss and guaranteeing access to the full nutritional program from day one.
For established plants or those with a longer production cycle, a technique called top dressing is employed. The CRF pellets are measured and spread onto the surface of the container media. This method is often used to re-fertilize a plant whose initial CRF charge has expired or to provide a supplemental boost for heavy feeders, as irrigation water dissolves and carries the nutrients down into the root zone.
Liquid fertilizers are most commonly applied using a technique called fertigation, which involves injecting concentrated water-soluble fertilizer directly into the main irrigation lines. This process delivers a precise, diluted nutrient solution every time the plant is watered, ensuring consistent and uniform feeding across thousands of plants simultaneously. Application scheduling is continuous, based on the plant’s growth stage and the CRF longevity, ensuring optimal feeding until the plant is ready for sale.