Mulching In The Garden: Why, How, and When!
Mulching isn't exactly glamorous or exciting, I know! It's one of the last things you think about when gardening. But over the years, I've realized how essential it is. It's like wearing sunscreen in the summer or putting on a sweater during winter!
A good mulch layer can transform your garden, protect your plants, and make a big difference. It offers so many benefits and can even make your garden look polished and inviting.
Let's dig into why you should mulch, the different types, and how to apply it effectively.
Contents:
Why Should You Mulch?
Mulching does much more than merely making flower beds look tidy. Here are a few of the main reasons why I never skip it now:
Moisture Retention
Mulch acts like a sponge, helping to keep the soil moist by reducing water evaporation. This is especially helpful in hot, dry climates, or during the peak of summer. It is the quickest and easiest way to save on water.
Weed Suppression
A nice thick layer of mulch helps block light from reaching weed seeds, which means fewer weeds and less time spent on garden maintenance.
Soil Temperature Regulation
Mulch insulates soil, keeping roots cooler in summer and warmer in winter. This temperature buffer can be a lifesaver for many plants.
Soil Enrichment
Organic mulches (like wood chips, straw, or compost) decompose over time, adding nutrients back into the soil. This constant recycling helps keep your garden soil rich and fertile.
Aesthetic Appeal
On top of all the practical benefits, mulch really does make a garden look complete. A neat layer of mulch gives the garden a cohesive, cared-for appearance.
READ MORE: How to make the best organic garden soil
Different Types of Mulch
There are many mulch options—each with its pros and cons.
Organic Mulch
Organic mulches break down over time, which enriches the soil but also means they need to be replenished periodically. Organic mulches also attract useful micro-organisms and earthworms.
Wood Chips and Bark
These options look great, are long-lasting, come in a range of sizes and styles, and are readily available. In some areas, tree services even provide them for free. Pine bark should ideally only be used on paths, not for mulching beds and borders. When you use it in your garden beds, they require a lot of nitrogen to break down, thus depleating your soil instead of giving back to it.
Straw
Straw is great for vegetable gardens and is our go-to mulch option. It's light, so it doesn't compact the soil, and it decomposes slowly, adding organic matter back to the soil. It's also a very cost-effective option. Straw is easy to either rake up or work into the soil when it's time to plant again.
Tip! Be careful not to use hay, as there are too many weed seeds. Always use a seedless straw.
Grass Clippings
Grass clippings are definitely the cheapest option. They are also very light, but they decompose quickly or get blown away by the wind, so they need to be replaced regularly. Just be sure not to lay them too thickly, or they'll start to smell and get slimy. Grass clippings can get matted and form a barrier preventing water penetration into the soil.
Pine Needles
Pine needles, or "pine straw," make an excellent, natural mulch, especially around acid-loving plants like blueberries, azaleas, and rhododendrons. Pine needles are lightweight, stay in place well, and decompose slowly, making them a long-lasting choice. They add organic matter to the soil, though over time, they can make soil slightly acidic, so they're best used around plants that prefer a lower pH.
Compost
Compost works double duty as mulch and fertilizer. It is great for keeping weeds off empty beds that are resting over winter, waiting for their spring planting. When you are ready to plant in spring, simply lightly fork the manure in, and you have well-fertilized, weed-free soil to start planting.
READ MORE: A Beginner’s guide on how to use compost in the garden
Shredded Leaves
Fallen leaves can make a wonderful, natural mulch. They're free, readily available, and decompose to enrich the soil. You'll want to shred them a bit as unshredded leaves will mat together and repel water in rainy areas.
Inorganic Mulch
Inorganic mulches don't break down, so they need less maintenance but won't add any nutrients to the soil.
Gravel and Stones
Gravel or stone mulch can look beautiful and is very durable for pathways and rock gardens. It also provides excellent drainage for plants that prefer drier conditions, like Mediterranean plants. But these are not the best options for less permanent plants like vegetables and annuals that get replaced often.
Landscape Fabric and Plastic
If you're trying to combat a serious weed problem, you can use landscape fabric under a layer of organic mulch. It's very effective, but it's not a good choice if you want the mulch to enrich the soil. Fabric and plastic are also best for foundation plantings, shrubs, and trees that are more permanent and don't require frequent fertilization.
Just be aware that plastic can get very hot for the plants and is not the most eco-conscious choice. In this case, landscape fabric is the more environmentally friendly choice.
Here is a picture of when we did not follow our own advice and used mulch in the garden beds. NOT a good decision and one we regretted immediately.
When to Apply Mulch
When you apply mulch depends a lot on your climate and what you're trying to achieve.
Spring
Spring is my favorite time to lay down a fresh layer of mulch. As the soil begins to warm up, the mulch will help keep weeds at bay and retain moisture for the growing season. However, you do want to pull back the mulch where spring bulbs and perennials will start to emerge.
Fall and Winter
In colder climates, adding mulch in the fall helps insulate roots and prevents soil from freezing and thawing too frequently. This can be especially helpful for tender perennials and younger plants. Mulch like compost or leaves will also replenish empty beds with nutrients during the dormant months.
After Planting
Anytime you plant new seedlings, it's a good idea to mulch around it. This helps keep soil moisture consistent and prevents weeds from competing with the new plant. BUT never mulch in beds planted where you have just planted seeds, as they need light and oxygen to germinate. Only mulch the soil after the seeds have grown.
How to Mulch Garden Beds
Mulching garden beds is pretty straightforward, but I've picked up a few tips and tricks over the years.
Prepare the Bed: First, I clear away any existing weeds. This might seem obvious, but it's important—mulch can suppress weeds, but it won't kill mature ones. You can also hoe the ground lightly to improve ventilation.
Water the Bed: I always water the garden bed before applying mulch. This ensures the soil beneath the mulch is well-moistened and helps plants stay hydrated.
Spread Evenly: When applying the mulch, I aim for an even layer. Too thin, and it won't suppress weeds or retain moisture well. Too thick, and it can block air from reaching the soil.
Keep Space Around Plant Stems: One mistake I've learned to avoid is piling mulch directly against plant stems or tree trunks. This can lead to rot and attract pests. I leave a small gap around each plant to keep the stem dry.
Tip! Do not mulch Mediterranean plants such as lavenders and rosemary as they do not like or need the extra moisture or nutrients.
READ MORE: Raised beds vs. in-ground beds—how to decide which is best
How to Mulch Around Trees
Mulching around trees is similar to garden beds, but we follow a few extra guidelines to protect the tree's health.
Create a Mulch Ring: I start by clearing a ring around the tree's base, removing any grass, weeds, or debris. Ideally, this ring should be about 3-4 feet in diameter.
Keep Mulch Away from the Trunk: One of the worst things you can do is create a "mulch volcano" by piling mulch up against the trunk. Leave a few inches of space around the trunk to allow airflow and prevent moisture buildup.
Spread Evenly: I apply the mulch in an even layer, just like in garden beds. The mulch ring not only looks neat but protects the tree's roots, reduces competition from grass, and helps retain moisture.
READ MORE: Grow bountiful fruit trees with the Ellen White tree planting method
How Thick Should Mulch Be?
For most garden beds, a 2-3-inch layer of mulch works best. Here's a general guide to follow:
Garden Beds: 2-3 inches of mulch is usually enough to retain moisture, suppress weeds, and insulate the soil.
Vegetable Gardens: For vegetable beds, 1-2 inches is usually sufficient. I don't want to smother young plants or make it difficult to sow seeds.
Trees: Around trees, you can go a bit thicker, around 3-4 inches. The extra depth helps to insulate the soil and protect the tree roots.
How to Calculate How Much Mulch You Need
Calculating mulch is pretty simple once you know the formula. Here's how to do it:
Measure the Area: First, measure the length and width of the area you want to mulch, then multiply them to get the square footage.
Convert Depth to Feet: Decide how thick you want your mulch layer (e.g., 2 inches), then divide by 12 to convert it to feet (e.g., 2 inches ÷ 12 = 0.167 feet).
Multiply by Depth: Multiply the square footage by the depth in feet to get the cubic feet of mulch needed. For example, for a 100-square-foot bed with a 2-inch layer, you'd need approximately 16.7 cubic feet of mulch.
Convert to Cubic Yards: Since mulch is usually sold by the cubic yard, divide your cubic feet by 27 (since 1 cubic yard = 27 cubic feet).
READ MORE: How much to plant per person in the vegetable garden
Mulching is one of the secret ingredients of a successful garden, friend. Whether you're trying to keep weeds at bay, protect young plants from the elements, save some water, or just give your garden a tidy look, it will greatly help!
I hope these tips help you make the most of mulching in your own garden.
Happy gardening! Annette, xx