All About Mulch

Healthy plants surrounded by a hardwood mulch.Garden mulch is simple topic that is often misunderstood by so many people. Mulch is far more than just a decorative finish for a garden bed. Used properly, mulch is one of the key ingredients for maintaining a healthy landscape. Used improperly and mulch can actually kill plants and drive off precious moisture.

Let’s start by discussing dyed mulches. Mulch that has been dyed red or black is some of the most popular mulch out there, and one doesn’t have to look twice to realize why. It looks fantastic and can really make a boring garden bed pop. It used to be the case that dyed mulches used toxic and unnatural dyes. On occasion, especially with the cheapest mulch from the big box stores, this is still the case. By and large however, most dyed mulches use iron oxide for red and carbon for black and darker brown mulch. The toxicity of the coloring is no longer the issue: The quality and composition of the shredded wood is our main area of concern. With low quality dyed mulch manufacturers of the cheap stuff often use wood that has been stained, treated, or otherwise contaminated with chemicals we’d rather keep out of the garden. Whether it has been treated with creosote, arsenic, or old varnish and stains, any scrap wood is fair game for these unscrupulous manufacturers. Old pallets are another popular source, but the unknown origin of the wood still presents a problem for gardeners.

When it comes to selecting a mulch, look for a seal from the Mulch and Soil Council that certifies that your mulch meets their standards. Here at Desiree Gardens we prefer a shredded hardwood mulch made from all natural wood such as fallen trees. The majority of our in-house mulch comes from arborists who have cut down or pruned trees and need us to recycle it into garden beds. Dyes, if they are used, consist solely of iron oxide (which can be great for your beds needing more iron) or just carbon for the black mulches. Keep in mind that if you are using a black mulch that is dyed with carbon, you will need to rebalance the soil by adding some all-nitrogen fertilizer such as a 15-0-0.

Another solution we use for dark and black mulches is to partially compost the mulch or mix it with an existing compost. At the end of the day mulch is not just decorative, it is designed to break down and amend the soil as freshly composted nutrients wash into and break down into a rich loam. Cheaper bagged mulch is often dried out and actually will repel moisture instead trapping it and keeping it in the soil.

Mulch over cardboard weed barrier.If weed control is one of your goals with mulch you might consider putting down a base layer of cardboard to act as a weed barrier. This all natural product (don’t use the glossy stuff) efficiently controls most weeds and is an excellent solution for helping the soil to retain moisture. Inks in all modern cardboard printing is vegetable based and will not harm your garden. Top your cardboard off with a nice hardwood mulch and the cardboard and mulch will slowly break down to provide nutrients for your soil as it does its job as decorative finish.

The biggest mistake we see with mulch is two-fold: Not raking out old mulch, and adding too much mulch. This phenomenon is most pronounced under trees that have been “mulched” by less scrupulous landscape companies. If you’ve seen mulch “volcanoes” underneath trees then you’ve seen what we’re talking about: 12″-24″ of mulch piled up against the a tree like a miniature mulch volcano with the tree trunk erupting from the middle. Do not do this! Not only is the mulch trapping moisture against the bark of the tree, which can lead to fungal infections, but this practice often results in roots rising up and eventually girdling the tree and killing it.

Properly applied, mulch should be 1″-2″ deep on the ground underneath the tree canopy and extending out to the drip edge. Depending on the size, age, and water requirements of the tree some gardeners make a small berm 4″-6″ tall around the outside of the canopy drip edge. This allows irrigation methods such as using a flood bubbler to deeply water the roots under the mulch circle.

If you’re refreshing mulch, rake out the old mulch first. Adding new mulch over old mulch that hasn’t properly broken down just compounds the problem. If you have old mulch like this, and you are sure it’s an all-natural mulch, simply remove it and add it to your compost bin where it can continue to break down slowly. Now you can replenish the mulch with a moist fresh batch of all natural wood and hopefully a little compost mix as well.

Need help with your irrigation or sprinkler system? Does your garden need an overhaul or just a general checkup? Give us a call at 877-558-1496, or drop us a line and contact us here, to find out how Desiree can help you create a wonderful garden with a budget you can afford.

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