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Why Pine Straw Mulch?

June 12, 2023


If you’ve been to Holden Arboretum lately you may have noticed a change in our mulch selection as seen in the Butterfly Garden and West Layer Rhododendron Garden.

Most gardeners are familiar with bagged mulch and the ease of use and of purchasing such a product – often needing more than 5 bags, with larger spaces requiring bulk purchases. But did you know that there is a better option? Consider pine straw mulch instead, minimizing single use plastic bags and reducing carbon emissions. Although, I should note that the twine used during the baling process is plastic – not ideal for compost-ability. However,  with some creativity,  it can be reused in other ways such as knitting reusable shopping bags.

So, are you wondering about the host of other reasons?

How sustainable is it?

Pine forests, grown for logging, are the primary source of this product. No machines are used during this process – instead, bales are hand raked & bundled and loaded onto trucks.

Since it is a lightweight product, it is more cost-effective to transport. Whereas, the weight of bagged goods and bulk mulch MUST be taken into consideration for hauling such large quantities of shredded mulches – 350 pine straw bales is equal to approximately 80 yards of mulch. Just imagine what 80 yards of mulch would look like! Now consider the process of delivering and storing such a delivery of shredded mulch.

Here at Holden Arboretum we have significantly reduced hauling to and from our gardens due to the light weight nature and the stack-ability of pine straw, reducing emissions and fuel costs, not to mention the reduction in labor required to mulch such vast garden beds!

Stock Photo

Is it really that good at weed suppression?

Here at Holden Arboretum, we are using long needle pine straw. Although it is quite fluffy when first applied to garden beds, it will interlock and mat down. This allows weed seeds to collect on top, preventing them from contacting the soil below. Traditional shredded mulch is not as effective at creating a barrier. One reason is that it takes less time for shredded mulch to break down & seeds find the gaps in the mulch, germinating much faster & easily rooting through it.

Seemingly, the mat-forming barrier of the pine straw is much more effective. Since mulching the garden bed seen below, I have pulled very few weeds. The seeds that have germinated, have done so in open areas where the mulch is thinner due to animals digging.

Of course, that’s not to say that seeds will never germinate on top of pine straw mulch – they can. But walk through a pine forest and there are very few weeds growing. Could it be the acid in the straw, as well? Although pine straw will not break down fast enough to affect the PH of the soil, it is possible that the acidity of the straw itself plays a role in preventing seeds from germinating.

West Layer Rhododendron Garden, Holden Arboretum

Why is it pollinator friendly?

Since it is so important for pollinators to leave leaf litter and cut stems for overwintering insects in garden beds, the pine straw can be strewn early enough to cover the vast amount of unsightly debris left from the previous season’s cuttings. This helps keep the overall aesthetics in tip top shape, while allowing the insects to emerge easily through the pine straw and out of their winter homes in cut stems.

Butterfly Garden, Holden Arboretum

What are the long-term cost savings?

The cost is comparable to regular shredded hardwood mulch on the first purchase but the overall, long-term, cost is lower due to the fact that you will not have to add as much pine straw the 2nd year (and beyond) as in the first. A little freshen up is all you need, filling bare spots as necessary.

Yeran Tribute Bed – Sherwin Pond, Holden Arboretum

Why it works –

It’s natural and non-dyed! Did you know that most dyed & shredded mulch sold in bags is actually shredded and dyed pallet wood?

Year after year homeowners have been taught to mulch their flower beds but is this the best practice? In short, no. What happens over time, is that shredded mulch builds up, burying plants and can, often, hold too much moisture around the crown or lower stems of plants, leading to rot in the crown of perennials and can cause the bark to crack on trees and shrubs. As a result, disease and pest issues can become problematic.

Note – shredded mulch should be kept at least two inches from the stems of plants, including the “crown” of perennials.

The downside to shredded pallets, specifically, is that the mulch forms a thick crust over time. It is this crust that reduces water and air from penetrating into the roots. As a result, the crust becomes hydrophobic during dry conditions, preventing water from reaching the roots. Most homeowners are unaware of the barrier that is created from repeatedly adding these products year after year. When watering, chances are, you’re just scratching the surface of the mulch & water is not reaching its intended location! As a result,  the plants struggle – roots grow upward in order to access air and water, instead of growing deep into the soil below. When roots sit close to the surface, plants are less cold hardy and less drought tolerant.

Pine straw is different – a light top dressing of pine straw can be placed up to and over the crown and stems of plants because it does not hold moisture like shredded hardwood or bagged mulches do. It allows water and air to penetrate deep into the soil and acts as a soil conditioner over time, keeping the soil structure light and airy.

The color is similar to oak leaves and provides a tidy, natural appearance.

Pine straw is easier on the back!

As you can see here, it is next to impossible to mulch a slope, at least it feels that way! Navigating plants and handling wheelbarrows or bins on any slope comes with hazards to you, as a gardener, to the landscaper and to the beloved plants on the hillside!

A much easier and lighter option is pine straw mulch! One bale of pine straw will go a long way & equals 45-50 square feet at a 2-3” depth. I should note that I have been applying it a little thicker in West Layer Rhododendron Garden,  so the square footage of coverage is slightly less at 40-45 square feet.

Butterfly Garden, Holden Arboretum

“Where can I purchase pine straw?” & “I don’t see it in garden centers!” – are questions I am often asked since using this product in West Layer. We are sourcing the product from a local-ish company in Cincinnati, Ohio . Homeowners can purchase this product from the same company we use here at Holden Arboretum and they will schedule a time to deliver it to your home!

Don’t be afraid to mulch early – we began mulching with pine straw in our respective gardens in early April! Unlike traditional shredded mulches – which are discouraged from being used until the ground warms and dries from the winter snow or cold spring rains – pine straw can be used as soon as the soil is workable. This opens gardeners up to getting a head start on mulching and, as a result, future weeding – two popular gardening chores!

Let us know what you think!

MaryAnn Thesing

MaryAnn Thesing


MaryAnn Thesing joined Holden Arboretum in May, 2022 as Horticulturist for “Old” Layer Rhododendron Garden, which includes the Murch Canopy Walk. MaryAnn has over 7 years’ experience as a Garden Designer/Installer & Garden Coach and is a Japanese Maple & Bonsai enthusiast, owner & caretaker of The Japanese Maple Garden in Euclid, OH for 16 years.

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