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Fertilize for Healthier Plants

Fertilize for Healthier Plants

All plants require light, air, water, and nutrients to grow. As they mature, plants use up the naturally occurring nutrients in the soil around the root zone. These nutrients need to be regularly replaced for the plants to continue to grow and remain strong. The plant food that gardeners provide is called fertilizer.

What do the Numbers Mean?

There are three numbers listed on all fertilizer packaging.

  • The first number is nitrogen (N). It’s responsible for promoting strong leaf and stem growth as well as plant colour. So, when foliage is normally a bright green and suddenly becomes pale, chances are nitrogen is required.
  • The second number is phosphorus (P) which promotes the strong root development that is essential for delivering nitrogen and other nutrients to the leaves. It also encourages greater flower production that, in the case of fruit, results in a larger crop.
  • The third number is potassium (K) which is needed for general vigor. It strengthens plants to resist insects and disease and to better withstand poor soil and drought.

Together, the three elements are referred to as “primary” micronutrients”. Micronutrients include copper, iron, manganese, zinc, boron, chlorine, and molybdenum. Some or all of these may be included in the formulation and are listed accordingly.

fertilized soil transfer

The actual number represents the percentage present of that element. Fertilizer often contains smaller quantities of nutrients like calcium, magnesium, and sulphur.

Why Are There Different Formulas?

Plants are individuals and they need different things.

  • Evergreens are mainly foliage plants and require a lot of nitrogen. The most common formula for this group is Evergreen & Shrub Food 30-10-10.
  • Annuals are grown for their continuous flowering so higher levels of phosphorus would be beneficial. Flower Plant Food 15-30-15 is excellent for promoting blooms that last longer.
  • To minimize the shock of transplanting, a formula like Transplanter 5-15-5 would immediately strengthen and promote root development.
  • Spring lawns need nitrogen to encourage strong, green growth. Lawn Food 21-6-12 is perfect for this purpose.
  • As weather gets cooler in the fall, lawns start to go dormant and their need for nitrogen is less. Fall Lawn Food 6-8-14 strengthens grass roots for winter with a higher concentration of phosphorus and builds up resistance to disease and injury with more potassium.

sprout in woodchip mulch

  • There are fertilizers available for specific needs. Super Phosphate 0-20-0 is just phosphorus for plants that may be sluggish about flowering.
  • Bulbs grow better with Holland Bulb Booster 9-9-6.
  • The formula for Jobes fertilizer spikes for roses is 12-16-12.
  • A simple way to feed most outdoor plants is with a general fertilizer like All Purpose Plant Food 20-20-20 or Garden-All 4-12-8, specifically formulated for vegetables.

One of the best ways to determine the health of your soil is with a test kit available at our Garden Centre.

How is Fertilizer Applied?

  • Fertilizer comes in a granular slow-release form or a compressed spike that’s pushed into the soil. It’s also available as a powder or liquid that is diluted with water.
  • Granulars are spread over the surface of the soil or lawn, at the recommended rate, by hand for smaller areas or with a spreader for larger areas. Generally, it lasts 6-8 weeks.
  • Spikes for trees and shrubs, fruit trees, and evergreens are pushed into the ground at the drip line in spring.
  • For mature specimens, a root feeder mixes water with a fertilizer pellet and distributes the solution through a long shaft pushed into the soil. It can also be used for deep watering during periods of prolonged drought.
  • Liquid and powder fertilizers are applied over a large area with a hose-end sprayer that attaches to a garden hose. Or, for small jobs, diluted with water in a watering can or bucket.

leaf in fertilized soil

When Are Fertilizers Applied?

  • Spring is the best time to fertilize when outdoor plants start growing again.
  • Be aware of the time period that fertilizers release nutrients so you know when or if you need to reapply.
  • Most granular fertilizer is slow-release and may be applied once or twice a year for perennial and mixed borders.
  • Lawns are fertilized 2-4 times a year depending on their general condition. Fertilizer spikes are put into the ground once in spring.
  • Anything mixed with water is quickly used by plants and is, therefore, applied more often.
  • Grass needs fall feeding. Stop fertilizing most plants after September 1, and roses by August 1.This allows the natural cycle of dormancy to take place rather than forcing growth that may not have time to harden off before winter.

What’s Organic Fertilizer?

  • Organic Fertilizer is derived from once living vegetable or animal material that may include kelp, seaweed, fish, bone meal (2-14-0), and blood meal (12-0-0). Even manure and compost can be considered organic fertilizers. Inorganic or synthetic fertilizers are manufactured from a chemical process or mined. The concentration of nutrients is usually higher.

Indoor Plant Fertilizer

Houseplants have their own needs.

  • Schultz Instant 10-15-10 is highly recommended for all.
  • For flowering plants try Schultz Bloom Builder 5-30-5.
  • African violets perform well with Schultz African Violet Plus 8-14-9 or Wilson Pow-R Caps 9-44-14.
  • Orchids like Schultz Orchid Food 19-31-17. Better-Gro makes two products for orchids: Orchid Bloom Booster 11-35-15 and Orchid Plus 20-14-13.

red cactus succulent

  • Even Cactus and Succulents have their own fertilizer. Schultz Cactus Plus 2-7-7 maintains healthy plants and promotes flowering.
  • Fertilize houseplants when they show active signs of growth. They often rest from November to March because light levels are low. At this time, it’s better to feed them once every 4-6 weeks.

In all cases, read package instructions carefully and follow dilution rates exactly. If in doubt ask the staff of trained horticulturists at our Garden Centre.