What color mulch should we use? I get asked this question all the time by my landscaping clients. Its an interesting question because the industry offers the consumer so many choices, but what is the right horticultural choice? Dose it matter to the health of your plants? Or is this just a purely aesthetic question?

The red mulch that you see everywhere these days started out as a solution to an international fast food chain's waste problem. Some very smart and savvy executive back at corporate headquarters here in Illinois was tasked with solving the problem of what to do with the disposal of a growing number of damaged wooden skids. The idea was to grind-up this waste and use it to mulch the landscape around their fast food stores. Why the bright red color? Well, their corporate colors are bright red and yellow. Red dyed mulches sold today may not all be ground waste materials, but they still are a wood based product. The key thing to remember is that it is ground wood.

Microbes, especially bacteria in our soils feed on the carbon in organic mulches. To consume this carbon, the microbes must also consume nitrogen. Initially this nitrogen comes from the soil. If the organic mulch has a ratio of carbon to nitrogen (C:N ratio) of 30:1 or less, then the microbes will return more nitrogen to our garden soil than is consumed in the composting process. Unfortunately wood mulches have a C:N ratio of 200:1 to 400:1. This means that wood mulches create a big nitrogen drain on our garden soils. And this can have a negative impact on the health of our landscape plants.

Cedar and Cypress mulches are also predominately wood based mulches. These types of mulches can have the same negative affect on soil nitrogen levels. So what is the best mulch to use in our gardens? Bark based mulches have a typical C:N ratio of 60:1. Though the composting action of a bark based mulch will reduce the soil nitrogen levels slightly, it has much less impact on our landscape plants than wood based mulches. Therefore, I always advise my clients to use a good quality, double shredded bark mulch. The health of our plants are much more important than the color of the mulch.

How do you keep back your grass from creeping into your landscape beds? How do you keep your mulch from washing out into your grass? Spade edging is one of the best solutions to both of these problems. What is a spade edge? You take your spade and dig straight down 3-4" along your plant bed edges. This vertical edge will not allow weeds to germinate and the "gutter" created by this cut will keep your mulch back when it rains. Grass spreads by underground, horizontal shoots called rhizomes. Rhizomes will turn away from these exposed spaded edges and grow back into your lawn, away from your plant beds. A good spade edge should last a full growing season. This means that it should be cleaned up each spring. Is a spaded edge the best edge for landscape beds in all situations? No! I was recently on a client's property where the spade edge would erode within three months. The reason for this condition was too much shade. With so much shade the grass was thin and weak and, therefore, there was not enough root mass in the lawn to hold the edge together. If your lawn is weak and thin, consider a different edge treatment than a spaded edge.

It's often said of Chicago voters that we vote often and early. The Lawn Care Industry would have us belive that the same should be true for our lawns, but fertilizing early and often in spring, particularly with a fast release fertilizer can be detrimental to ours lawns. Research shows us that early applications of fast release nitrogen in this area can lead to disease problems later in the season. So when should we fertilize in spring? Its best to fertilize after the grass is actively growing. If you have mowed your lawn two times (because it was needed), then we can consider fertilizing our lawns. Don't apply more than 1 lb. of nitrogen per 1,000 Sq. Ft. and use a fertilizer with at least 50% slow release nitrogen. Plan on only one spring fertilizer application. Any more than one application is just an invitation to disease and unneccessary. Happy mowing!