FERTILIZING
FERTILIZING TIPS
A few general fertilizing tips for our prairie–foothills climate, where soils tend to be alkaline, low in organic matter, and often quite dry. Our recommendations for fertilizing are in keeping with our mission to contribute to greener, healthier and more sustainable communities.
Key Ingredients
Along with climate, moisture and soil conditions, there are several nutrients important for plant growth, but we’ll stick to the big three here. You’ll generally find these letters on a fertilizer label and the numbers represent the percentage by weight of each nutrient.
Nitrogen (N)
– Drives green, leafy growth.
– Helps plants build chlorophyll and established deciduous trees thicken their canopies.
– Use mid spring/summer.
-Avoid use on newly planted trees, conifers and in late summer/fall.
Phosphorus (P)
– Supports root development, helping young plants establish faster.
– Encourages flowering and fruiting.
– Use at planting time for trees, shrubs, and perennials, especially for fruiting and flowering trees and shrubs.
– Bone meal is a natural source.
– Avoid use when you’re planting native prairie species (they prefer low-P soils).
Potassium (K)
– Strengthens cell walls.
– Boosts disease resistance, improves drought tolerance, and enhances winter. hardiness — very important in Alberta.
– Use for trees and shrubs going into winter, in dry, sandy, or alkaline soils (common in Southern Alberta), for fruiting plants to improve quality and yield, and/or when plants look weak or stressed despite adequate water.
– Wood ash is a natural source (use sparingly; raises pH), as are kelp meal and compost.
Fertilizing Newly Planted Trees in Southern Alberta
1. What newly planted trees actually need.
New trees don’t need heavy fertilization. Their priority is root establishment, not fast top growth. Over‑fertilizing, especially with high‑nitrogen products, can stress the tree or push leafy growth at the expense of roots.
2. The essentials for the first 1–2 years:
– Moisture: deep, consistent watering is more important than fertilizer.
– Soil structure: Roots spread best in loose, well‑aerated soil.
– Organic matter: Helps retain moisture and improves nutrient availability.
– Mild, slow‑release nutrients: Enough to support root development without burning.
3. When to Fertilize:
– At planting: Use organic matter and gentle amendments, not strong fertilizers.
– First growing season: Avoid high‑nitrogen fertilizers.
– Second year onward: Light fertilization in early spring can help if soil is poor.
4. Natural Fertilizers/Soil Amendments:
All of these are gentle, slow‑release, and safe for new plantings when used correctly.
Compost (yard waste or municipal)
– Widely available at: local garden centres, municipal compost depots.
– Benefits: Improves soil structure, moisture retention, and microbial life.
– How to use: Mix a small amount into the backfill and apply 2–3 cm as a surface mulch.
Composted (not fresh) manure (cow, sheep, chicken)
– Slow release
– Adds organic matter and nutrients.
– How to use: Apply sparingly as a top dressing or mixed into the top 10–15 cm of soil around the tree, not directly against the trunk or in the hole.
Bone meal
– Provides phosphorus for root development.
– How to use: Mix a small amount into the planting hole or apply around the dripline.
Mycorrhizal inoculants
– Helps roots absorb water and nutrients more efficiently.
– How to use: Apply directly to roots at planting.
Wood mulch (natural, not dyed)
– Conserves moisture, moderates soil temperature, slowly adds organic matter.
– How to use: 5–10 cm layer, keeping a gap around the trunk so mulch does not suffocate the root flare, as “volcano mulching” can cause rot.
Sample Fertilizing Plan
At planting:
– Mix compost into backfill (10–20%).
– Add bone meal or mycorrhizae if desired.
– Water deeply.
First year:
– Focus on watering.
– Add a thin layer of compost or composted manure in mid‑summer if soil is very poor.
– Maintain mulch.
Second year:
– In early spring, apply a light top‑dressing of compost or composted manure.
– Water deeply during dry spells.
Different Plants = Different Needs
- Coniferous Trees (spruce, pine, fir, cedar):
– grow more slowly and dislike strong fertilizers.
– conifers benefit from organic matter that gently lowers pH in the alkaline soil conditions of Southern Alberta.
– mulch is especially helpful.
- Deciduous Trees (aspen, poplar, elm, maple, fruit trees):
– more nutrients than conifers, especially if they’re fast‑growing species.
– organic matter–rich soil to support rapid root and canopy development.
– consistent moisture during establishment.
- Shrubs (ornamental or fruiting):
– shrubs often establish faster.
– moderate addition of organic matter
moisture is important, as shallow root systems dry out more quickly than trees.
– occasional nutrient boosts are helpful, especially fruiting shrubs like currants, raspberries, or haskaps.