6 Things to Know About Pine Straw Mulch

Not every mulch is created the same. Pine straw could be a great choice if you know what to expect.

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In some areas of the country, the choice between pine needles and wood mulch is a tough one. Since the 1980s pine straw has been the favorite mulch in the South. It is inexpensive, effective, and attractive, especially in the vicinity of the ever-present loblolly and longleaf pines.

Like most mulches, pine needles contribute valuable organic matter to the soil, supporting an impressive diversity of native and ornamental landscape plants including trees, shrubs, perennials, and annuals. If you’re considering pine straw for your landscape, here are a few things you should know.

1. Pine straw mulch is lighter in weight than wood mulch.

Mulch weight might not be the first thing on your mind as you begin a spring landscape cleanup. But after loading up, unloading, and spreading a few bags, your arms and back might start asking questions. Wood mulch is deceivingly heavy, but pine straw can be deceptively lightweight.

The best way to compare the two is by taking a look at coverage per pound. A single bale of pine straw, weighing on average 35 pounds, covers about 50 square feet. Compare that to a standard 2-cubic-foot bag of wood mulch that weighs about 25 pounds and covers 12 square feet.

The pine straw covers close to 1.5 square feet per pound, while wood mulch covers about 0.5 square feet per pound. That’s one-third the weight per square foot of coverage, or three times the coverage per pound by pine straw!

RELATED: The Dos and Don’ts of Mulching the Garden

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2. Pine straw mulch can be sustainable.

The pine straw that is sold in stores and landscape supply centers is harvested from timber farms. These privately held properties are managed for a diverse set of goals, so measuring the environmental impact of the straw harvest is a complex undertaking that differs from one property to the next.

But, homeowners who have loblolly or longleaf pine trees in their own yards can take advantage of fallen needles by reusing them to mulch the landscape, rather than bagging and disposing of them. It’s free mulch, and you only have to pick out the cones and sticks. This is a more sustainable way to keep the driveway, lawn, and deck clear, while protecting and beautifying landscape beds.

3. Pine straw mulch is significantly less expensive.

To compare the cost of pine straw versus mulch, look again at the coverage per bag of mulch versus coverage per bale of pine straw. It’s pretty common to see 2-cubic-foot bags of wood mulch for sale at three for $10, or $3.33 each. Since each bag covers 12 square feet, that’s 36 square feet for $10, or 3.6 square feet per dollar.

At an average cost of about $4 per bale, and each bale covering about 50 square feet, pine straw comes in at 12.5 square feet per dollar. Buying pine straw instead of wood mulch stretches a dollar nearly 3.5 times further.

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RELATED: How to Make Mulch from Scratch

4. Pine straw is an excellent insulator.

In addition to conserving moisture, preventing erosion, and blocking weeds, pine straw mulch also helps to keep the soil cool in summer and warm in winter. Its lofty structure creates trapped air space, like a blanket. The trapped air resists daily air temperature swings due to daytime and nighttime differentials and warm or cold fronts passing through.

It takes long-term heat or cold due to seasonal changes to affect the soil temperature beneath the mulch layer. So, pine straw protects plant roots both in summer and in winter.

5. Pine needles maintain soil moisture well.

The same qualities that allow pine straw mulch to protect soil from temperature swings also help to conserve soil moisture. Water perks into and evaporates out of soil through tiny pore-like channels. This well-defined structure is a sign of good soil health and also allows plants to establish deep root systems. If the soil surface is unprotected from the sun’s rays, it dries out quickly.

A layer of pine needle mulch on the soil surface creates trapped air space that allows liquid water to pass through into the soil. But because of its cooling effect, it greatly reduces moisture loss through evaporation.

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RELATED: How to Mulch Your Flower Beds

6. Pine straw mulch isn’t the best option for preventing weeds. 

While pine straw makes an excellent protective covering to maintain soil temperature, structure, and moisture levels, it does have a weak point. Compared with other mulch types, it does not do a great job of smothering weeds. The open structure allows moisture and light to penetrate deeply into the surface, which encourages weed seed germination. It also makes a wonderful habitat for trailing perennials like Virginia creeper, bermuda grass, poison ivy, and others to spread where they’re not wanted.

Control weeds in mulched areas by maintaining a 3-inch deep layer of pine straw, applying weed preventer, pulling weeds before they go to seed, and by spraying judiciously with liquid weed killer.