002 GGW – Why leaves shed in fall, disposing of chemicals, mulch

This week’s featured stories include a follow-up to last week. Now that you know why leaves change color each autumn, learn why leaves fall in fall. Also, learn more about the latest issues with Plastic Pot Recycling. So many pots—so few options! Plus, learn how to Choose Organic Products with Confidence. We also hear a tip about how to avoid buying bulk mulch containing hazardous materials, and Joe answers a listener’s question about disposing of garden chemicals safely. Free Book giveaway opportunities included throughout the show!

002 Show Notes

Why do Leaves Shed in Fall?

Wouldn’t it be nice to enjoy those brilliant autumn leaf colors all year– rather than for a few short weeks? Maybe so, but the changing leaf color each fall is part of an important and complicated process that ends in their being shed at the end of each growing season. The actual term used to describe the process of leaf drop is known as abscission.

Although some parts of trees (like stems and buds) can handle freezing temperatures, most leaves cannot. So, in order to protect themselves, trees and plants shed diseased, damaged or dead tissue (namely leaves) – while simultaneously sealing the point where the leaf petiole connects to it. The abscission layer (as it’s known) consists of unique cells that can separate from each other based on certain physiological occurrences.

As changing climate and light conditions of autumn evolve, hormones within trees change too. The most notable is auxin. It’s produced in the leaves and body of trees and plants. This balance of auxin levels between leaves and branches is key to determining if and when leaf drop occurs.

During the active growing season, production rates of auxin in leaves are consistent with other parts of the plant or tree. As long as these rates are steady, the cells of the abscission layer remain connected. That, in turn, keeps leaves attached. However as days shorten and temperatures cool, auxin production in leaves starts to decrease in response to changing conditions. This causes fracture lines to develop at the base of the leaf petioles, and scarring builds up at the same point to form a protective barrier. Eventually, it’s just a matter of time before wind or rain provides that last nudge, and the leaves are released, at least for most trees.

Oaks and beech trees are another story. They hang on to many of their leaves well beyond that of other broadleaf, deciduous trees. These brown and tan, dead-looking marcescent leaves cling to branches until newly emerging growth pushes them off in spring.

Although leaves falling in autumn is a predictable event, leaf drop is not only seasonal. Plants and trees can lose their leaves for a number of reasons, namely drought and other physical or environmental stresses. Although any tree is subject to leaf drop under such conditions, not all trees are considered deciduous or even semi-deciduous. Narrow-leafed evergreens such as fir, hemlock, pine, and spruce are able to survive winter without foliage loss for two reasons. First, their leaves develop a protective waxy coating. Second, the fluid inside their cells contains a version of nature’s antifreeze. The attached foliage remains undamaged, so there’s no need for it to be shed.

While evergreen trees are beautiful year-round, deciduous trees are desirable for another reason. Their leaves provide vital organic matter and build structure and water holding capacity in the soil. So each autumn, enjoy and savor the brilliant display of color, and in winter take pleasure in the evergreens. At the same time, be thankful for all those leaves on the ground. They’re doing more good than you might have ever imagined.

Much Ado About Mulch; Buyer Beware

This week’s tip deals with buying mulch in bulk or by the truckload. I’m a big fan of mulch. I always have been. The more I learn about all the direct benefits, the bigger fan I become. Yet, what I didn’t know about the potential hazards was even more important!

A couple of years ago, I was in search of some bulk mulch. When I arrived at the town’s local source for these products, my heart raced. In the distance, I could see mountains of what appeared to be well-ground and thoroughly-composted mulch. I like to think of it as black gold. The worker offered to drive me down to the mulch pile in his truck for a closer look. I was so excited that I barely noticed the cold and rain. Upon inspection, I saw what looked to be exactly what I was hoping for – a nice combination of coarsely-ground branches, sticks and leaves. It was all composted and ready for my garden…or so I thought.

Buyer Beware. I asked my host how he was able to create such a massive and seemingly endless volume of product, considering we were in such a small town. He proudly went on to explain that he had many sources. The City delivered waste from fallen trees and such, and landscapers and weekend warriors offloaded their accumulations of a hard days work, etc. Then, he went on to say something that took me back. Some of this mulch was the remnants of former decks, play sets, fence posts, and more. I realized all that gorgeous mulch was also full of lots of treated wood, chemicals, paint, varnish, etc. All that translates into four letter words if you speak organic!

As a gardener who tries to be as chemical-free as possible, this mulch source was no longer an option. It was no coincidence that about the same time, I suddenly noticed the rain and how cold it really was. The lesson I learned from this experience was to be much more cognizant of what might be in my mulch and to always ask where its coming from. Hopefully, you will too.

So, what’s the answer to finding mulch that’s free of any unacceptable material – like arsenic-laden pressure treated wood? Unfortunately, there’s not yet a national certification program for bulk mulch. If you buy mulch in bulk, you should do whatever is necessary to make sure you feel comfortable. Know the source of the mulch. That might include talking to supplier management staff or seeing if they have any documentation on what’s in their mulch. Physical inspection is something I always make time for too.

Plastic Pot Recycling-One Silver Lining in an Otherwise Dismal Effort

As gardeners and weekend warriors, we do so much to beautify our lawns and landscapes. But in the process of planting, pruning and ongoing maintenance, we generate a great deal of waste. Sadly, much of that ends up in the landfill. Of the total landfill volume, estimates list the percentage of compostable waste from yard debris at about 12%.

Another contribution we gardeners make to this mountain of waste is the millions of plastic pots we discard each year. Unfortunately, options for what we do with them once they’re empty are much more limited. Unlike yard debris, plastic pots can’t be composted and most aren’t easily recycled. So even the best intentioned, environmentally conscience steward is given few options when it comes to responsible disposal.

According to the EPA, of the nearly 27 million tons of plastic generated in the United States in 2003, only 3.9 of it was recycled—and very little of that was garden-related. Unfortunately, gardeners are in for a long wait before recycling horticultural plastic is widely accepted by processing facilities. Of the pots that can be recycled, most municipalities lack the resources to manually segregate those from the many more that can’t. Adding to the problem, manufacturers, growers and nurseries have yet to seriously consider a uniform standard for recyclable containers, and with many variables and competitive interests to consider, finding an acceptable solution will be difficult.

Yet in the midst of this less than encouraging news, positive things are happening. Since 1997, the Missouri Botanical Garden’s Plastic Pot Recycling program has successfully prevented over 300 tons of horticultural waste from going into landfills. The Garden’s successful program in St. Louis is the most extensive public garden-recycling program in the United States.

Elsewhere, there is a concerted effort by a group in the nursery and landscape industry to consolidate horticultural container sizes in an attempt to simplify the recycling process. Although I applaud their efforts, standard sizes will have little effect on the bigger problem. I believe the answer is to standardize the materials used to make the containers so they’re all recyclable, no matter what the size. It will no doubt take the cooperation from many sides. The nursery and landscape industry and we as home gardeners and weekend warriors do great things to beautify the environment, but we need a way to eliminate the impact left behind in doing so.

Disposing of chemicals safely: This week’s question comes to us from a listener in Michigan. She wants to know what are on a lot of people’s minds these days, and for good reason!

Collectively I can only imagine how many leftover containers and bags of lawn and garden chemicals are sitting around the sheds, and basements of the world! In our very busy and time-starved lives, it would be easy to pour the excess chemicals out into the street or down a drain. But Pesticides or any chemical for that matter poured into the street feed directly into storm drains which feed into streams, rivers, ponds and lakes. When these chemicals reach waterways, they can harm fish, plants and other living things.

Similarly, they should never be poured down the sink, tub, toilet, or into the sewer or street drain. Pesticides can interfere with the operation of wastewater treatment systems and many municipal systems are not even equipped to remove all pesticide residues.

So what can we do to dispose of chemicals properly and safely? Well, According to the Environmental Protection Agency and other sources, The first thing we can do is to use or give them to your neighbor so they can use them to treat a similar pest control problem. Although this is certainly a valid way to consume the product, personally I find it hard to suggest using more chemicals in your landscape simply to use it up.

The second option to consider is that most local municipalities have a department that deals with waste management and can advise you on how to dispose of excess chemicals other than by using them. Some even have a household hazardous waste collection program. Once or twice a year, many cities or counties provide a place for you to take such chemicals where they can be properly and professionally disposed of. You can find more information on these programs by contacting your local government agency. You may find the appropriate department listed under solid waste, public works, garbage, trash, or refuse collection.

In the United States, a third option is to call a toll free number for information and sites for recycling and disposing of hazardous household waste in your area. The number is 1-800-CLEANUP. An automated recording will guide you through the process and the number is accessible 24/7.

Of course you can always (and should) read the product label for disposal information. But be aware that state and/or local laws may be more restrictive than the Federal requirements listed on the label. Check with your local authorities before disposing according only to information listed on the product label.

Bonus Information:

According to the EPA, empty containers can be disposed of with your other solid waste after proper rinsing. A triple rinse is suggested before disposing. First, fill the container ¼ full with water, close the lid tightly and vigorously shake. The rinse water should be applied to an area needing treatment. Never pour the contents down the sink. Repeat the process two more times. Don’t triple rinse pesticide containers in a kitchen sink.

But you should also know this; some municipalities don’t even allow empty pesticide containers to be disposed of with solid waste. Instead, they’re considered as household hazardous waste and treated accordingly as I’ve already mentioned.

So now you know, disposal of pesticides should never be acted upon without taking the proper precautions. There’s a saying we use around my house to reduce the clutter; “When in doubt, throw it out”. And although that applies to much of the junk we accumulate, it does NOT apply to pesticides. Our health and environment depend on it.

There’s even more to this story, like what to do with the empty containers. And it’s not as simple as throwing them out. We have the expanded version of this explanation on the website. Dispose of chemicals safely.

Taking the Mystery out of Organic Fertilizers

So it’s finally cool for mainstream America to be green. Organic products are showing up everywhere from what we put in our gardens to the clothes we wear on our back. Some organic choices require very little thought, such as selecting organic carrots. But it’s not that simple when it comes to selecting eco-friendly products for your lawn or garden and fertilizer to grow food organically. Well that’s the subject of today’s feature. But now that you’ve decided to grow green, you’re as confused as the next guy when it comes to actually knowing what fertilizer to buy and how are natural products better?

So first the background; All plants receive their nutrients in chemical form. They can’t distinguish between how the nutrients were derived, whether organic or non-organic. When referring to plant nutrition, organic or natural generally refers to any fertilizer, which is derived from plant, animal or mineral origin, and it must have one or more essential nutrients for plant growth.

Non-organic fertilizers (also known as synthetic) on the other hand are manufactured chemically and therefore are usually listed simply by their numerical nutrient analysis on the packaging. They’re made to deliver nutrients rapidly, such as those that are water-soluble, or over time as a controlled release. Although synthetics are very effective for providing rapid or prolonged periods of feeding, they have a high salt index. The potential risk to plants and the soil food web is burning and dehydration with the leeching of unabsorbed chemicals into waterways and aquifers.

Unlike synthetics, organic alternatives are often listed not by the numbers but primarily by what they actually are, such as blood or bone meal or fish emulsion. These nutrients must first be broken down and digested by soil microorganisms, which then release them in a form available to plants. This process also produces humus, a vital ingredient to improving soil structure. As part of this structure, organically derived nutrients are highly resistant to leeching and contain a very low salt index. The net result is nutrients that remain in the soil until utilized by plants and little risk of burning or dehydration, even in periods of extreme drought or over application.

Organic soil amendments are a readily available way to provide all of the elements considered essential for plant growth that are absorbed from the surrounding soil. I rely on these natural amendments to ensure I’m feeding the soil, which in turn feeds the plants. It’s a safe, effective and environmentally responsible approach to gardening.

For an expanded version of this discussion, including a list of organic nutrient options to meet all your fertilization needs, there’s an article waiting for you on our website.