How to Mulch in Winter | 8 Reasons why you should

Mulching in winter will protect your plants and soil. Mulch works like a blanket to balance soil temperature, protect soil microbes and keep nutrients in your soil. Adding mulch to your soil before and during winter is important to keep your plants happy and healthy until spring.

Why you should mulch in winter

  1. Keep soil in place in heavy rain
  2. Keep nutrients in your soil
  3. Balance soil temperature
  4. Protect soil microbes
  5. Protect garden worms
  6. Stop plant root from freezing
  7. Spread water more evenly through the soil
  8. Prevent winter weed growth
Adding bark mulch to soil will help to protect plant roots and soil over winter.

Why you need to mulch in winter

Keep nutrients in your soil

Adding mulch to your garden beds in preparation for winter will help to stop too much water soaking your ground and washing away nutrients and microbes. The mulch you add to your garden in fall and winter will absorb some of the excess rain and move it more evenly through you soil.

Mulch will also stop heavy rain from washing your soil away from your garden beds. Mulch like straw, bark chips or fall leaves will hold the soil in place and keep your plant roots safe.

Add mulch to the top of flower garden beds, vegetable gardens and to the top of pots and containers to keep excess moisture.

Use straw mulch on top of vegetable garden beds over winter.

Balance soil temperature

Mulch added in winter will help to even out the soil temperature in the upper layers for your plants. Mulch acts like a winter blanket so keeps heat in longer and slows down how quickly your soil cools overnight.

Keeping your garden soil a more even temperature will help to avoid plant stress and help to prevent root damage. Adding a good layer of mulch in winter will take care of your plants so they are ready to add on new growth in spring.

Protect your soil microbes

Cover your soil with mulch in winter to protect the soil microbes. Soil that does not have mulch cover can freeze over winter which can kill off soil microbes.

The top layers of soil are very important for your plants as they contain most of the soil microbes. They work to break down organic matter and release nutrients in a way that makes them available to plants. If your soil gets too cold, the soil microbes may not survive.

Solve this by adding a 3-4 inch layer of mulch to the top of your soil to protect the microbes. Garden worms also feed on the microbes so keeping them alive will also keep your worms happy.

I add mixed tree mulch around annual flowers, Mediterranean herbs and around citrus trees.

Mulch prevents winter weed growth

Mulch your garden in winter to stop fast growing weeds from taking nutrients from your plants. I live in a sub-tropical climate and winter weeds will quickly take over any garden soil that is not covered in mulch.

If you live in a warmer area like me winter mulching is very important to stop your garden from being taken over by winter weeds. Chickweed and soursobs are quick to grow over winter. I always cover my soil with bark chips or sugar cane mulch in winter to stop them from taking over.

This area of my garden has some winter weeds coming through bare soil.

Best mulch for winter

Here are my favorite mulches to use in winter in different areas of your garden.

Plant typeWinter MulchAlternative mulch
Citrus TreesMixed tree mulchBark chips
Vegetable gardensStraw mulchSugar cane mulch
Strawberry PatchStraw mulchSugar cane mulch
Perennial flower bedsMixed tree mulchBark chips
Annual flowersMixed tree mulchBark chips
Tropical Fruit trees (eg. Mango)Sugar cane mulchStraw mulch
Apple and Pear treesMixed tree muchBark chips
Stone fruit trees (eg. Apricots)Mixed tree mulchLucerne
Mediterranean herbs (eg. Thyme)Bark chipsSugar cane mulch
Soft herbs (eg. Basil)StrawSugar cane mulch

Winter Mulches – A quick guide

Mixed tree mulch

Mixed tree mulch is made from tree trimmings and contains both leaf pieces, plant stems and branch piece. The mix of green and brown material breaks down quicker than mulch with only large bark chips so adds nutrients to your soil quicker. It will keep the soil an even temperature over winter.

Use mulch between stepping stones to prevent weeds.

Straw mulch

Straw mulch is a low cost, light weight mulch perfect for protecting vegetable gardens over the winter. It breaks down quickly adding organic matter to the soil and works well to insulate the soil against winter frosts.

Sugar cane mulch

Sugar cane mulch works similarly to straw mulch and will form a nice blanket over your soil in winter. Use sugar cane mulch if you live in an are that it is easy to access or if you can’t find straw mulch. I like sugar cane mulch because it uses up a waste product of the sugar industry while protecting my winter garden.

I like to use sugar cane mulch under tropical trees like mangoes.

Lucerne Mulch

Lucerne mulch is a nutrient rich alternative to straw or sugar cane mulch. It is a more expensive option but will contain more nitrogen to feed soil microbes over winter.

Lucerne will be higher in nitrogen than other mulches but is also more expensive.

Using compost as mulch in winter

Another great mulch option for winter that will work on all areas of your garden is compost. If you are have space for a compost bin at home, this can be the perfect material to add to your garden in fall before the winter chill.

Compost will protect the soil by evening out the temperature changes and will also feed soil microbes. As the soil microbes digest the compost they will make a small amount of heat which will also help to keep your soil temperatures more even.

Compost is best added as a layer underneath the other mulches I mentioned above. Layer 1-2 inches of compost then layer another inch of tree mulch, straw or sugar cane mulch on your garden. Compost on its own can dry out slightly which is why layering is the best option.

Fall leaves and leaf mold

Fall leaves can be used as a mulch in winter by adding them directly on open garden beds, around large trees or perennial shrubs. If you have made leaf compost or leaf mold the previous year, this will also work as a great mulch for winter.

I am making leaf compost in my new compost bag.

Fall leaves that have not broken down can blow away in windy areas so I like to collect them up and break them down into a compost ready for the next year.

Checkout my previous article on how to make compost without manure to find out more about making compost with just fall leaves.

Mulching in winter – Summary

Mulching in winter is important to protect your plants and soil. Add a 2-3 inch layer of mulch to the top of garden beds and underneath your vegetables to protect and prepare your garden ready for spring.

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