What is an invasive species?

In the last post, That Blog asked what a native plant is. Asking what an invasive plant is might seem redundant – if it’s not native, it must be invasive, right?

Actually, no. If it’s not native, it must be non-native. But not all non-native plants are invasive. An invasive plant is one that meets a special definition:

An invasive plant is one which tends to spread, and which causes harm to the local ecosystem.

A non-native plant that stays put in a garden, or that escapes into the wild but causes no discernible disruption to the existing plant community, is not considered to be invasive.

Where do invasive species come from? Some – like Kentucky bluegrass – arrive by accident, as stowaways in other shipments. But half or more of the invasive species spreading across the United States today were deliberately introduced by the nursery trade. People planted these ornamental exotics in their yards, and the plants then cheerfully multiplied beyond the property lines.

In recent years, some states have tried to deal with this problem by banning the sale of invasive species. Some of these measures have passed; others have not. Even when they do pass, though, they tend to ban plants which have already been sold in abundance, and which have already spread into natural areas. Once a species has invaded an area, it is usually very difficult to eradicate. Banning the continued sale of such species is unlikely to make a dent in the problem.

An approach that might be more effective is to make every property owner responsible for eliminating invasives from their own land: if we each take care of our own piece of the Earth, together we might be able to accomplish something. Municipalities have used this approach for a long time, in the form of banning so-called “noxious weeds”. But these weed bans are often not enforced, and, more importantly, they tend to take aim at plants that are unpopular, rather than focusing on plants that are truly harmful. As just one example, these rules often forbid milkweed, the family of native flowers that are crucial to the survival of the monarch butterfly.

Before we pause to reflect on That Blog’s third anniversary, let’s take a look at one more definition worth knowing: a naturalized plant is not one that has settled harmoniously into its new home. Rather, it is a non-native species that is capable of surviving and reproducing without human help; in other words, a species poised to become invasive.

What is an invasive species?

What’s new in natural yards? May 2018

A recently-published study (authored in part by That Blogger’s former thesis advisor) examines how Wisconsinites think about their urban trees.

A 16-page survey sent to homeowners in and around Milwaukee, Madison, Green Bay, and Wausau asked people a variety of questions about trees. One set of questions regarded benefits and problems related to trees. Under the header of benefits, survey respondents most strongly valued trees for their ability to make a place look nice, provide shade and cooling, improve air quality, and generally enhance the livability of a neighborhood.

But about half of the homeowners said they were “strongly concerned” about the risk of trees or branches falling and damaging things. People within city limits (as opposed to those living in the suburbs) and people with smaller lots tended to be more worried about this risk, possibly because a falling tree or branch on their property was more likely to hit something. People who saw trees as dangerous, the study found, valued trees less overall.

The survey also asked who homeowners trusted for help and advice related to trees. The results showed that respondents trusted tree professionals more than any other source of information. Averaged across the four cities, 62% of people said they would trust a landscaping company or tree service, while only 14% said they would trust the staff of a non-profit organization. This is surprising and worrying, as such professionals have a financial incentive to suggest whatever service is most profitable for them, rather than the service that is best for the tree and its neighbors (human and otherwise).

The survey’s demographic questions turned up some interesting findings. Women rated trees more highly than men did, and millennials valued trees more than baby boomers, though these younger folks tended to have fewer trees on their own properties, likely because their lots were smaller than those of their more senior neighbors. Older homeowners, in contrast, expressed more concern about trees “growing too big, making a mess, or blocking scenic views”.

Finally, most people who answered the survey thought that their neighbors valued trees and took good care of trees. But, as with many domains of life, people rated themselves even more highly on questions about recognizing the importance of trees and properly caring for trees.

The relatively-brief, highly-readable report can be found here.

What’s new in natural yards? May 2018

What are some common natural gardening mistakes?

When natural gardeners are asked about their biggest gardening mistake, one answer is heard over and over: trying to do everything at once.

Their enthusiasm is commendable. After all, natural yards are beautiful and peaceful, they provide habitat for wildlife, they take less work in the long run, they are good for the environment, and they benefit our health in countless ways. Who wouldn’t want one right now?

One of the biggest obstacles to establishing a natural yard, however, is the amount of work they require upfront. The aspiring natural gardener has to learn about native plants and the site conditions they prefer, survey their own site conditions, make a garden plan, eliminate existing non-natives, bring in the new plantings, discourage the invasives that try to move back in, and many other tasks. In many natural yards, all of this work is done personally and by hand, rather than by hiring other people or fossil-fuel-powered machines to help with the labor.

Thus, for any but the tiniest of yards, the gardener can quickly become overwhelmed by the amount of work that needs to be done all at the same time. Aspects of the planting begin to fail. (In a natural yard, it’s accepted that some things will fail, but trying to rush through the establishment phase tends to lead to more failure than necessary.) The gardener has run out of money, resources, and energy to do the project over again. Pretty soon, they’re left with a big mess.

For this reason, experienced natural gardeners advise newcomers to make an overall plan, then tackle one aspect at a time. It’s generally wise to start with trees and shrubs, which take the longest to become established, and add smaller plants later. Or, the beginning gardener could begin with the areas closest to the house, and work outwards. As each piece of the plan becomes self-sustaining, the gardener becomes free to devote their energy to the next stage of the process.

Another mistake worth mentioning is declaring failure too soon. As mentioned in the previous post, new plantings may take several years to start looking good. Seeds may not germinate in the first year. Seeds that do germinate may look like weeds. Transplants may appear to have not survived their relocation.

All of these are normal parts of the establishment process. Seeds will germinate when they are ready, seedlings will mature into beautiful plants, and transplants will jettison their leaves, focus on getting their roots settled, and grow back the next year. By patiently waiting out these awkward stages, a gardener can avoid unnecessary rework.

Part of the joy of having a natural yard is the satisfaction of learning about native plants through hands-on experience. It’s not necessary to be an expert on natural gardening before beginning to establish plantings in our own yards. But by arming ourselves with a little awareness of others’ mistakes, we can increase our own chances of speedy success.

What are some common natural gardening mistakes?

Why are lawnmowers so loud?

Strictly speaking, lawnmowers are loud because they work by creating a vacuum, and vacuums make a lot of noise.

Looked at more broadly, however, it could be said that lawnmowers are loud because the purpose of mowing a lawn is to make as much noise as possible, so everyone will know that someone is mowing their lawn.

It’s possible to have a lawn without making a lot of noise. A homeowner could plant low-growing or slow-growing grasses, which stay at a lawn-like height while being mowed rarely to never. Homeowners could landscape with moss gardens, which are visually similar to lawns but don’t require any loud maintenance. Homeowners could install astroturf. They could use a virtually-silent reel mower. Or they could employ an automatic lawnmower, a small and quiet device which has been commercially available since the 1950s but which has never achieved widespread popularity.

Why have these quieter, simpler alternatives never caught on? In short, it is because the historical purpose of lawns is to be maintenance-intensive, in order to show off that the property owner can afford to spend their money and leisure time preventing grass from growing. This message is conveyed when neighbors see naturally-tall grasses staying perpetually short – but it is conveyed more effectively when everyone can see and hear the property owner actively maintaining their short grass.

Oddly enough, when some homeowners tried out automatic lawnmowers, their neighbors did not say, “Look at that smart guy enjoying a nice day while a robot does his yard work.” Instead, they said, “Look at that lazy guy lying in the hammock while a robot does his yard work.” For many people, what matters is not that the yard work is done; it’s that the homeowner does the yard work personally (or hires other humans to do it at obvious expense), and is observed to be doing it.

Noise harms neighbors. Lawns do not benefit neighbors. Those who care about their communities are increasingly embracing low-maintenance natural yards, or at least switching to quieter, less damaging ways of managing their turf.

Why are lawnmowers so loud?

How do you get people to stop walking on the grass?

We’ve all seen them: signs asking us not to walk on the grass. Some property managers even put up fences to keep people off the lawns.

Why is this? Lawns are good at very few things. They don’t clean the air as effectively as other types of plantings. They don’t absorb as much water. They aren’t especially pretty and they don’t do much for our health. They provide habitat for very few animals, and they take a lot of work. But one thing lawns do excel at is putting up with being walked on.

Lawns, by their nature, invite people to walk on them, to play soccer on them, to spread out a blanket and have a picnic on them. Lawns are an excellent landscaping solution for any area that is meant to be used in that way. Any area that is not meant to be walked on, sat on, and played on, quite simply, should not be lawn.

When an area is planted with anything taller and denser than a lawn – be it prairie plantings, a row of shrubs, or closely-spaced trees – people instinctively don’t try to walk over it or through it. A few dedicated hikers will cheerfully plunge in, but most casual pedestrians will stick to the nearest path without even thinking about it.

Therefore, to stop people from walking on the grass, plant anything other than short grass.

A lawn that is not meant to be walked on is a kind of landscaping oxymoron. Anyone who finds themselves with such a lawn should ask themselves one question: What is this area for? If it is for strolling and sunbathing, take down the signs. If not, plant it with something people can enjoy walking alongside… and still take down the signs. You won’t need them.

How do you get people to stop walking on the grass?

What’s new in natural yards? January 2018

A candidate in this year’s Wisconsin gubernatorial race has named lawns as an issue he would address if elected. In a post on his campaign website, Jeff Rumbaugh says that if he becomes the governor, he will not ban lawns, but will work with municipalities to make alternative forms of gardening more accessible to property owners.

As a reason for this position, Rumbaugh focuses on the wasteful water consumption associated with lawns. He also mentions the connection between lawns and climate change, and the amount of work involved in maintaining a lawn. He proposes wildflower plantings, vegetable gardens, and gravel as more environmentally-responsible kinds of yards.

Rumbaugh’s campaign promise follows California’s statewide restrictions on lawns – effective as of December 2015 – and Madison’s easing of its regulations on natural yards. Meanwhile, a governmental task force in Delaware has recommended phasing out the use of non-native plants, which currently make up more than 70% of the plants sold at garden centers around the state.

Evidence is gathering that the era of the lawn as a dominant element in American landscaping is at an end. Natural yards are likely to become much more common over the next several years. There is still time for savvy homeowners to be part of this mainstream movement, rather than being the last on their block to adopt new gardening practices.


That Blog does not endorse political candidates. This post is simply a commentary on the continuing emergence of lawns as a political issue.

What’s new in natural yards? January 2018

Are lawns more attractive than natural yards?

As with property values, attractiveness is mostly in the eyes of the beholder.

By some objective definitions, however, it can be fairly said that natural yards are more attractive than lawns. For example, an idea called Attention Restoration Theory suggests that we inherently prefer to look at plants growing in their natural forms. Under this theory, humans like to look at plants, animals, clouds, water, and other natural things, because those are the kinds of things we evolved to look at. Hence, our brains are good at looking at those kinds of things, and we find these scenes mentally restful.

In contrast, our brains are not good at dealing with cars, ATMs, microwaves, DVR remotes, and all the other trappings of modern life. Looking at unnatural things is mentally tiring, leaving us with fewer resources for activities like learning difficult material, paying attention to boring tasks, and staying calm in stressful situations. Looking at nature, Attention Restoration Theory concludes, gives our brain a break, and helps us recover our full capacities.

When people say that humans find lawns attractive, they tend to invoke a different evolutionary theory: the idea that lawns resemble our ancestral habitat. In fact, there is little evidence to support the notion that humans evolved around very short grass. (Grass as short as a typical lawn does not even exist anywhere in nature.) On the contrary, humans evolved on the savanna, an ecosystem dominated by grasses about three feet high.

Current leading research on human evolution says that we are creatures of tall grass; we even owe our bipedal stance to tall grass. On the savanna, not being able to see over the grass is a big disadvantage. Many grassland animals dealt with this problem by evolving longer legs or necks, but humans did it by unfolding themselves and starting to walk upright.

Setting aside the evolutionary theories, it could also simply be said that natural yards are more interesting to look at. They are more diverse. They change over time. Plants move in the wind, and animals move among them. Walking through a natural yard tends to reward the visitor with the opportunity to see things that were previously hidden.

A lawn, in contrast, remains static across days and seasons and years. It generally includes little activity, and walking across it doesn’t bring into view anything that couldn’t be seen from the original vantage point. If the word “attractive” describes something that draws you towards it, then a healthy plant community certainly embodies this characteristic more than a flat monoculture.

Are lawns more attractive than natural yards?

Why does new construction tend to come with a lawn?

If lawns don’t help property values, why are they still so popular in new construction? The original developer of a site, after all, has no interest in the site aside from how much he can sell it for, so he should be motivated to use whatever type of landscaping is likely to bring the highest price.

The answer is that establishing a lawn is easy, cheap, and fast. Unlike a natural yard, which typically takes three years to begin looking as intended, or trees, which take decades to mature, a lawn can look good just a few weeks after its initial seeding. When potential buyers make offers based on what they see today, without considering the future, it’s unsurprising that they’re willing to pay more for a green lawn than for a stand of tiny trees or a carpet of unsprouted native seeds.

In fact, developers are betting that their customers care more about how the yard looks today than what it will be like down the road. Of the many turf blends that are available, developers usually choose the ones that are best able to establish quickly. These blends, though, are typically not the ones best-suited to long-term survival on any particular site. Thus, the specific kind of lawn the developer chose may look lush and healthy on move-in day, but the new homeowners quickly find that it is nearly impossible to maintain.

Wouldn’t it be cheapest, fastest, easiest, and most valuable to preserve the existing mature landscaping on a construction site? Many developers say that it is too difficult and expensive to build a new home without disturbing the plants that already live there; they generally prefer to bulldoze everything and install a brand-new garden after everything else is done.

Studies suggest, however, that protecting plants creates relatively little cost or inconvenience for developers. After accounting for the value an established natural plant community can add to a new home’s sale price, developers who take the trouble to avoid flattening vegetation typically come out ahead. A new home with mature landscaping is, after all, a rare and desirable combination.

Why does new construction tend to come with a lawn?

Do lawns increase property values?

Lawn service companies often claim that lawns increase property values. Conversely, those who are unhappy with a neighbor’s natural yard often say they don’t like it because it hurts their property values. Are these claims true? There are two answers to this question.

#1: It’s impossible to say.

In some court cases over property owners’ rights to have a natural yard, judges did not accept arguments that natural yards hurt property values. The judges pointed out that property values are influenced by so many things – the size of the home, the quality of the local school district, the recent sale prices of nearby homes, and the general housing market, just to name a few – that it is impossible to say that any one factor is helping or hurting property values in any one neighborhood.

#2. Compared to what?

Lawn service companies typically base their claims on studies that compare lawns to bare soil or to truly unmaintained masses of invasive plants. When asked to compare lawns to natural yards, a surveyed group of real estate agents believed that the natural yards came out ahead, raising property values by as much as 10%.

Ultimately, the value of a property is nothing more than what a potential buyer is willing to pay for it. In the past, when many people did not like or understand natural yards, it may have been true that buyers were willing to pay more for a lawn than for a planting of wildflowers. As attitudes change, however, buyers are not likely to be willing to pay a premium for an expensive-to-maintain lawn, when they could buy a well-established natural yard, move right in, and enjoy the birds instead of firing up the lawnmower every weekend.

Do lawns increase property values?

What is perception of care?

Perception of care is the belief, on the part of a viewer, that a landscape is being taken care of by a human. This belief is often the difference between an observer complaining that a space is not being maintained, and an observer appreciating that the property owner is being ecologically responsible with their land.

It is important to note that perception of care is not about fooling people into thinking an area is being managed when in fact it is not. Rather, perception of care is about helping others understand that a planting is intentionally designed to look as though it was put there by nature.

Over the decades, natural gardeners have found that they can create perception of care by including elements that serve as signals that a yard is being taken care of. Effective signals include:

  • Human-centric features. Elements that are obviously more useful to people than to wildlife – such as a bench, a path, or a statue – show that a garden is designed by a human and is intended to be welcoming to humans.
  • Clear borders. A definite edge to a planting serves as a cue that a planting was established on purpose, and has not just sprung up on its own. A decorative fence makes an obvious border, as does a narrow swath of mulch or gravel, or a mowed strip.
  • White things. People tend to perceive white things as clean and well-maintained, and this perception will extend to the entire yard. If the aforementioned statue or decorative fence is white, it will serve double-duty as a signal that this is a well-cared-for space.
  • Explanatory signs. Nothing says “this is an intentional natural yard” like a sign bearing the text “This is an intentional natural yard.” A quick internet search will turn up many examples of signs identifying and explaining the importance of pollinator habitat, standing dead trees, and natural yards in general.

Some studies suggest that trying to make a natural yard look acceptable to lawn-loving neighbors can drastically reduce the yard’s value to wildlife, but a few well-placed cues to care can prevent conflict at little cost to the homeowner or the environment.

What is perception of care?