Mulch is necessary when soil and plant roots need protection from conditions they can't handle well on their own — temperature swings, moisture loss, weed pressure, and erosion. It's one of the most high-value, low-effort things you can do in a garden.

Core reasons mulch becomes necessary:

Moisture retention — bare soil loses water rapidly through evaporation, so if you're watering frequently but soil dries out fast, mulch is needed

Weed suppression — exposed soil is an open invitation for weeds; a 2–3 inch layer blocks most weed seeds from germinating

Temperature regulation — mulch insulates roots from summer heat and winter freeze-thaw cycles, which are particularly hard on plants in Ontario

Soil erosion — if rain is washing soil out of beds or down slopes, mulch absorbs impact and holds soil in place

Soil health — organic mulches break down over time and feed soil biology, improving structure similarly to topdressing on a lawn

Specific situations that call for it:

Newly planted trees, shrubs, or perennials — roots are establishing and need consistent moisture and temperature protection

Garden beds going into winter — a fresh layer protects perennial roots from hard freezes

Around trees in lawn areas — prevents mower and string trimmer damage to bark, which is a leading cause of tree decline

Vegetable gardens — keeps soil warm, reduces disease splash-back from rain, and suppresses weeds between rows

How much to apply:

2–3 inches is the standard for most beds

Keep mulch a few inches away from plant stems and tree trunks — piling it against bark (called "volcano mulching") traps moisture and causes rot and pest damage

How often: Organic mulches decompose and need topping up annually or every two years depending on the material. Shredded hardwood and wood chips last longer than straw or grass clippings.

Types and when to use them:

Shredded hardwood or bark — best all-purpose choice for ornamental beds, long-lasting

Wood chips — great around trees and shrubs, breaks down slowly

Straw — ideal for vegetable gardens and overseeded lawn areas

Compost — doubles as a soil amendment, good for vegetable beds but breaks down quickly

Stone/gravel — permanent, low maintenance, good for drainage-focused areas but doesn't improve soil