You Should Mulch Your Flower Beds Now for Better Blooms in the Spring—Here's How

Winter mulch safeguards delicate plants from cold damage and enhances plant health by improving soil structure, boosting watering retention, and suppressing weeds. However, mulch needs to be applied at the right time and in the right way for maximum benefits—and some plants shouldn’t be mulched at all! If you’re ready to master the art of winter mulching.

This guide will walk you through the basics of when and how to mulch flower beds over winter and help you avoid common mulching mistakes.

When Should You Apply Winter Mulch?

Timing your winter mulch application correctly can help you avoid damaged roots and flower buds, and it may even extend your growing season. But exactly when mulch should be applied depends on the types of plants you’re growing and your growing zone.

Annuals

Since annuals are generally more cold-sensitive than perennial plants, it makes sense that they should be mulched a bit earlier. For the most part, the best time to mulch annuals is when the weather begins to cool and before the first frost.

Perennials

Mulching perennials too early can keep plants from entering winter dormancy and increase the chances of cold damage. To avoid this, mulch perennials when the plants die back after the first hard freeze.

Vegetables

Some cold hardy vegetables can be grown through winter in mild climates, but they’re more likely to survive with some mulch. For best results, treat plants like beets, carrots, and radishes like annuals and mulch them when the weather begins to cool.

Trees and Shrubs

Like perennials, trees and shrubs should be mulched after the first hard freeze. Mulching these plants too early may attract rodents and increase the chances of rot.

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5 Benefits of Winter Mulching

Alan Mitchell, the head gardener of Dr. Neil’s Garden in Edinburgh, Scotland, explains how winter mulching is useful in many ways.

“It suppresses weeds, retains moisture, helps plants cope with temperature extremes, and is especially beneficial for establishing young trees," Mitchell says. “It also clearly outlines an area around plants where you shouldn't cut or trim grass."

Adding organic matter to the soil will help with fertility and moisture retention, Mitchell adds. Clearly, winter mulching has many advantages and it helps plants in a number of different ways. But as Mitchell points out, some of the main reasons why you may want to mulch in winter include:

• Plant protection. Winter mulch is particularly helpful for plants on the edge of their hardiness zone, as well as new plantings. It protects tender stems and shoots from frost damage and reduces frost heaving, which can harm roots and unearth shallow plants.
• Soil improvement. Mulch adds organic matter to the soil as it breaks down, but mulching also improves water retention, stabilizes soil temperatures, and prevents erosion.
• Reduced weeds. Weedy growth slows in winter, but sturdy weeds can have a growth spurt during spells of warm weather. However, weeds have a much harder time intruding if you keep your soil covered with mulch.
• Less work in spring. Mulching in winter can help you cross off one item on your busy spring gardening to-do list.
• Wildlife habitat. Natural mulches provide a habitat for hibernating pollinators and other beneficial insects. Not to mention, mulching also increases the activity of earthworms and beneficial microbes.

Which Plants Shouldn't You Mulch in Winter?

Although mulch is beneficial to most plants, there are a few plants that you may want to avoid mulching altogether. If you do decide to mulch these plants, apply only a light layer of mulch around their roots.

• Rot sensitive plants. Mulch is well-tolerated by plants that naturally grow in moist soils and shady spots, but it may not be the best choice for some plants that prefer drier soil. This includes woody-stemmed herbs, like lavender and creeping thyme, as well as salvia and veronica.
• Succulents. Succulents, like sedum, also prefer relatively dry soil and they may rot under thick layers of mulch.
• Spring bulbs. Many spring bulbs don’t need mulch and heavy applications of mulch can keep them from sprouting.
• Self-sowing plants. If you want plants like coneflowers and black-eyed Susan to self-sow seeds, avoid adding much mulch. These plants readily self-sow if you let them, while mulching can limit their spread.

How Much Mulch Do You Need for Winter?

Today, there are tons of natural mulches to choose from. Wood and bark mulches, as well as pine straw, are always popular picks for ornamental beds, while compost and weed-free straw are commonly used in vegetable gardens.

How much mulch you’ll need for your garden depends on how deep you’d like your mulch layer to be and the particle size of the mulch.

Fine Particle Mulches

Compost, grass clippings, and other fine-grained mulches should be applied in layers that measure between 1 and 3 inches deep. Thicker applications of these mulches can condense and cause drainage issues.  

Coarse Particle Mulches

Straw, chopped autumn leaves, and mulches made of other bulky items should be applied in thicker, 3 to 6-inch deep layers. Thin applications of these mulches can allow weed seeds to sprout.

No matter what type of mulch you choose to use, you’ll need about 1/3 of a cubic yard of mulch to cover 100 square feet of gardening space with 1 inch of mulch. That means that if you want to apply 3 inches of straw mulch over a 100-square-foot veggie garden, you’ll need about 1 cubic yard of mulch.