Forests lack gardeners. In the wild, there is no one to rake fallen leaves or blow them away. Foliage falls from trees and onto the ground, where it stays as it decomposes. It is the natural process. Raking and blowing leaf litter away is unnatural. It deprives the soil and organisms that inhabit it of significant organic matter that they crave. It also interferes with insulation and moisture retention.
Of course, there are some natural processes that are not so desirable in home gardens. After all, that is why raking and blowing is standard procedure. It is not practical to leave leaf litter on lawn, ground cover, pavement or roofs. Raking and blowing removes leaf litter from where it is unwanted, or at least moves it to where it is less visible. Leaf litter seems to be so useless and unwanted.
However, other procedures are necessary to compensate for the lack of leaf litter. Mulching insulates soil, retains soil moisture, and inhibits weed growth. Watering adjusts to deficient moisture in exposed soil. Weeding eliminates weeds that germinate and grow where there is nothing to inhibit them from doing so. Herbicide may be more practical. It is all so contrary to natural processes.
It is somewhat obvious why deciduous plants defoliate through autumn and winter. They do not need their foliage as much while days are shorter and sunlight is less intense. Also, they do not want to be battered by winter wind, or collect heavy snow. Yet, their desire to mulch their own soil is not so obvious. Evergreen plants do it also. They just do it slower, and generally throughout the year.
In fact, many evergreen plants are more efficient with their mulch than most deciduous plants are. Leaf litter of eucalypti, camphor, bay and nearly all conifers actually has a preemergent herbicidal effect. It inhibits germination of seed that can reach the soil. It can be a disadvantage for wildflowers, or an advantage for weed control. Incidentally, coniferous leaf litter is likely to be combustible.
Leaf litter, composted or left to its natural processes, is natural.
Fads are not necessarily bad ideas. Some evolve out of good ideas. Others are recycled old ideas that worked. The current popularity of stone, gravel and artificial ‘dry creek beds’ is probably the result of the drought. Yet, they were becoming popular before the drought. This is not their first time around either. They were popular through the 1970s and the 1950s as well.
Stone and gravel obviously do not need to be watered. Therefore, more area occupied by stone, gravel or dry creek beds equates to less area occupied by plants that want water. Such areas are not as useful as pavement or decking, but are more appealing where space does not need to be useful, and work nicely where the ground it sloped too much for pavement.
Stone around the trunks of mature trees works like an insulating mulch so that lawn grass and groundcover plants can be kept at a safe distance. Otherwise, the water needed to sustain the grass or plants against trunks can cause root or trunk rot. However, stone should not be piled so deeply that it holds moisture or interferes with aeration.
Stone is actually better than mulch in some situations. It does not decay. Stones and larger gravel are not likely to be blown or raked away, although small gravel can be difficult to separate from debris while raking. Since stone does not need to be replenished, groundcloth can be installed beneath it to prevent weeds from growing through.
Artificial dry creek beds do not need to be completely dry all the time. They can actually improve drainage in low spots that get saturated during rain. Stone on groundcloth drains better than soil or plants do. Artificial creek beds that are only ornamental should stay in low spots anyway. They look even more unnatural in high spots that water would not naturally drain to.
A few plants can go a long way in larger areas of stone or gravel, and particularly in artificial dry creek beds. If the stone is done properly and is appealing enough, the plants merely add a bit of color, form and texture, without completely obscuring the stone. Drought tolerant plants are of course more appropriate if the intention of stone is to conserve water.
Every living thing in our gardens came from the wild somewhere. A few plants might be natives trying to adapt to synthetic landscapes. Some might be from similar climates. Some are likely from very different climates. Even houseplants came from the wild somewhere in the World. Regardless of their respective origins, in home gardens, all plants want to behave as they would in the wild.
Many plants want to defoliate at this time of year. Even some evergreens want to shed some of their old foliage before winter. Some perennials die back to the ground. Most summer annuals are already dead. There is an abundance of deteriorating organic material getting discarded by the plants that produce it. In the wild, all this detritus would naturally fall to the ground and decompose.
That might be a problem in parts of our refined landscapes. Fallen leaves must be raked from lawns, decks, pavement and various other flat spaces outside. If left too long, they shade out lawns, ground cover and bedding plans. Fallen leaves can stain decking and pavement too. The worst diseases of roses and fruit trees overwinter in fallen infected debris that does not get raked away.
Unfortunately, raking the mess of autumn away deprives the plants that live in the garden of the abundant decomposing organic matter that they expect to be delivered this time of year. The soil is left exposed and uninsulated, allowing temperature and moisture content to fluctuate more than they would naturally. Nutrients are not replenished as readily as they would be from decomposition.
Mulch, which can be applied at any time of the year, is quite seasonably appropriate in autumn. This is when plants expect decomposing organic matter to arrive from above. Mulch compensates for the loss of what we consider to be a mess, but what plants consider to be an important component to their natural ecology. It gives them what they want, but is neat enough for refined gardens.
The best mulch for the job just might be fallen leaves that were raked last year and composted, perhaps with other debris from the kitchen and garden.
Most plants would prefer the real thing; how they do it in the wild. They drop their leaves, flowers and twigs. Deciduous plants do it mostly in autumn. Evergreens might spread it out through the year. The debris accumulates on the ground below, and decomposes at about the same rate as it accumulates. There is no one there to clean it up. Yet, the natural ecosystems know what to do.
The plants that produce the debris use the nutrients produced by its decomposition. So, with the help of the many microorganisms in the soil, they recycle their own trash. To exploit this resource most efficiently, feeder roots tend to congregate near the surface of the soil where the nutrients are. Because the debris also insulates and shades the soil surface, roots are comfortable there.
Densely forested ecosystems produce the most debris. Many smaller plants in such ecosystems may disperse their roots exclusively into decomposing debris without reaching into soil below. In desert ecosystems, where such debris is minimal, roots are mostly dispersed much deeper to avoid the hot and dry soil surface. They wait for recycled nutrients to leach to them through the soil.
Redwoods, cypresses, many pines and most eucalyptus produce unusually thick layers of debris that decompose slowly. This technique inhibits or prevents the germination of seeds of potentially competitive plants. So, in other words, these trees and other plants had this, as well as moisture retention, soil insulation and nutrient recycling, all figured out long before we knew about mulching.
After we put so much work into raking and disposing of foliar debris that would otherwise accumulate in our gardens, it is ironic that we sometimes need to apply seasoned mulch to compensate for the lack of organic material on the surface of the soil. (Unseasoned mulch draws nitrogen from the soil to sustain its own decomposition.) It does more than merely improve the appearance of otherwise exposed soil. Mulch helps unnatural landscape environments function a bit more naturally.
It is silly for us to think that we know more about gardening that the plants who live out in the garden full time. We can help them along by giving them a bit more of what they need to survive, such as water and fertilizer. We can prune them to help them concentrate their resources into bloom and fruit production. Through it all though, we really need to be observant of what they do naturally.
For example, we water many plants through dry summer and autumn weather because we know that they are naturally endemic to climates that provide a bit of rain throughout the year, and that they can get dry without it. We fertilize them when they are actively growing because we know that is when they want it. Most deciduous plants get pruned in winter because they are dormant then.
This time of year, deciduous plants are defoliating in a very obvious manner. Evergreen plants are more subtle about shedding some of their foliage. Defoliation and shedding happens this time of year because plants do not need so much foliage, if any, when there is not so much sunlight for foliage to exploit. The days are shorter, and the sun is at a lower angle, so sunlight is less direct.
There are other reasons why winter defoliation is sensible. It makes deciduous plants more aerodynamic, and less likely to be damaged or blown down than they would be if they kept their foliage for wintery winds to blow against. Likewise, when the weather gets frosty, defoliated deciduous plants leave little to get ruined. What does all this suggest for seasonal garden chores for autumn?
Mulch, which can be spread at any time, is particularly timely for autumn, because that is when the garden expects organic material from above. Just like fallen leaves would do in the wild, mulch settles in through rainy winter weather, and helps to retain moisture after the rain stops next spring. It inhibits weeds that will want to grow as soon as the rain starts, and insulates perennials that grow slower or go dormant when the weather gets cooler. Mulch helps an unnaturally cultivated garden do what it wants to do naturally.
‘Fertilizer’ is a polite term for ‘recycled vegetation’.
‘Recycled vegetation’ is a polite term for something else.
This is not a synthetic type of fertilizer that gets tossed about or poured on. It gets added to compost and allowed to compost some more before being spread out as a mulch over the surface of the soil, just before chipped vegetation gets dispersed over the top. Alternatively, it sometimes gets mixed into the soil. It is quite useful. You can’t beat the price.
It is recycled differently from the compost or chipped vegetation (from a brush chipper). It is recycled through a horse, or more specifically, two horses. As the picture above suggests, it begins at the front of the horse, and ends at the rear of the horse, which is not pictured.
The horses happen to be quite efficient at recycling vegetation. They do it all the time. They are probably doing it right now. I would describe the process, but I do not know how it works.
Three times weekly, on Mondays, Wednesdays and Fridays, some poor sucker must go to where the horses live and work to collect the binned ‘fertilizer’, and deliver it to the compost pile. By the time it gets mixed into the compost, and composted more, it is not recognizable. Otherwise, it might be a problem in the parts of the landscape where it gets dispersed with the compost.
The landscape seems to like it. Only a few plants with special needs get any sort of synthetic fertilizer.
This sort of recycling is not new technology. It has been around as long as horses have been serving humans. In fact, it was not even invented by humans. Horses were doing it long before humans merely discovered, refined and took the credit for it.