the garden professors

Bee Lawns: What’s all the buzz about?

October 14, 2022

Bee Lawns: What’s all the buzz about?

A bee lawn is a way to benefit pollinators in our landscapes by providing additional floral resources, and often utilizes a mix of low-growing flowering plants in addition to turf species. Although flower gardens also provide flowering plants for pollinators, bee lawns can be multi-functional in their usability for recreational purposes with the added benefit of providing food for bees.

Habitat loss is one of the major factors implicated in the global declines of native bee species. Providing resources utilized by these critical pollinators can assist in mitigating this. Research through University of Minnesota has found 50 species of bees utilizing the flowers in bee lawns.

The purpose of bee lawns includes providing nutritious sources of nectar and pollen for pollinators, especially in urban environments, where these resources can often be scarce and difficult to find. Additional factors include recreational usability, and reducing inputs, e.g., irrigation, nutrients, weed control, and time spent mowing. Flowering plants suited for bee lawns have a variety of common characteristics including: low-growing and flowering heights, perennial life cycles, the ability to persist with turf species, and tolerance of mowing and foot traffic.

An important consideration is that bee lawns don’t necessarily mean weedy lawns or no-maintenance lawns, but instead require different types of management and serve different functions than traditional turfgrass lawns.

Not all bee lawns are created equal, and some work better than others.

Here are some turfgrass species that can work well for bee lawns:

Cool-season turf

A mix of fine fescues (which includes species such as: creeping red fescue, chewings fescue, hard fescue, and sheep fescue) are some of the best options for bee lawns due to reduced needs for inputs including irrigation, fertilizer, and weed controls, in addition to their compatibility with flowering plants…

…click on the above link to read the rest…

“How dry I am “: Four types of drought and how they can affect gardeners and gardens

November 27, 2021

“How dry I am “: Four types of drought and how they can affect gardeners and gardens

Linda’s post last week about “drought-resistant” plants made me think about drought and how different types of drought affect gardeners in different ways. In her article, she defined drought as “an unusual lack of rainfall”. This is one of four different kinds of drought that climatologists talk about, and I thought it might be interesting for you to hear about how the four (or maybe five) types of drought differ and how they affect gardeners in diverse ways. A great source of drought information across the U.S. is https://www.drought.gov/.

360° panorama of the northern end on the lake bed of a drying Lake Albert in Wagga Wagga, New South Wales, Australia, source: Bidgee, Commons Wikimedia.

Meteorological drought

The first type of drought, the one Linda described last week, is what climatologists consider a meteorological drought. A meteorological drought is related to how much rain you get compared to usual conditions at your location. I like to think of it as “too many days of nice weather in a row”, since in these dry conditions, the sun is shining and it is a great time to garden, play golf, or do construction. Of course, if you don’t get rain for a long time, you start to see impacts on plants, water bodies, and wells, but meteorological drought is usually not identified in terms of impacts, just on the amount of precipitation measured over weeks, months or years. Meteorological droughts look different depending on where you are. It is possible to have drought even in a desert if rain does not fall over an unusually long time…

…click on the above link to read the rest of the article…

Plant lists that shouldn’t exist

November 23, 2021

Plant lists that shouldn’t exist

Nothing drives me crazier than simplistic solutions to complex problems. Given our changing climate, there has been an explosion of “drought tolerant” and “firewise” plant lists in the gardening world. Most of these lists are devoid of science and all of them are removed from reality. The fact is that taxonomy plays a minimal role in determining whether a plant will tolerate environmental extremes.

**Lack of irrigation and mulch guarantees a drought-stressed landscape regardless of the selected species.**

Let’s start with the most obvious problems with these lists. The goal isn’t to have plants that require less additional water – it’s to have a landscape that requires less additional water. Similarly, the relative flammability of plants is less important than whether the landscape surrounding those plants is protected from fire. Plants don’t exist in vacuum and unless you are strictly a container gardener a single plant’s impact on water use or fire resilience is negligible. So a gardener’s questions should be “How can I make my landscape more drought tolerant? How can I reduce the likelihood of wildfire damage?” And these are questions that can be addressed with knowledge gleaned from applied plant and soil sciences.

Drought Tolerance

***Arborvitae can tolerate droughty summers, but they don’t tolerate improper planting and management.***

First of all, let’s think about what “drought” really means: it’s an unusual lack of rainfall. It doesn’t mean no irrigation, and it doesn’t mean dry soil. Drought is a climatological term, not one associated with soil water management. Fine roots and their root hairs require water to function. Without sufficient soil water plants will go dormant or die, particularly during establishment. Plants that are drought tolerant can tolerate seasonal lack of rainfall, but they can’t tolerate chronically dry soil conditions.

***Even “drought tolerant” species like Sempervivum will die if there’s not enough soil water.***

…click on the above link to read the rest of the article…

Pruning established trees

November 13, 2021

Pruning established trees

This month I continue the series on pruning with a look at pruning established landscape trees. These are trees in the prime of life, growing well, starting to shade the garden beneath them and expanding their canopies. Various reasons can prompt the call for tree care professionals.

What reasons would we have to prune a healthy vigorous mid-aged tree? For those we have to examine what may have happened in the past. The fact that a tree is growing well does not always mean it was “selected” well. After a few years time, that cute little nursery tree is flexing its branches and spreading out and, more worryingly, upward. One of the prime reasons for pruning is to reduce the size or expansion of a tree canopy. There may be impending interference with power transmission or other utility lines. The tree may be blocking a view, it may just be frightening in its shear mass or size and pose a psychological threat to its owner. Size reduction is a frequent object of tree pruning operations.

The tree is too large for my comfort

If you find that you want to reduce size of a tree you should ask yourself is it possible and is it sustainable? Ultimately, do I have the right tree for this spot?
Size reduction pruning is a battle with tree genetics. The tree wants to achieve a designated height and the tree owner wants to limit that height. Terminal or leaders can be pruned back to a lateral branch to reduce the length of stems and branches. This kind of “thinning” is effective as long as the branch that a leader is trimmed to is large enough to resume the hormonal role for that portion of the tree…

…click on the above link to read the rest of the article…

Why root washing is important – an illustrated cautionary tale

October 26, 2021

Why root washing is important – an illustrated cautionary tale

I’ve promoted root washing of containerized and B&B trees and shrubs for a few decades now. The experimental science is slowly coming along – it can take several years to determine if the practice is more successful in terms of plant survival than leaving the rootball intact. But we know how soils function in terms of water, air and root movement, and we understand woody plant physiology. So it’s pretty easy to predict what will happen when trees, whose roots are held captive in layers of stuff, are then planted, intact, into the landscape.

Early in spring 2021 I purchased a couple of Japanese maples to frame our garage. As always, I root washed these specimens. Here’s a play by play of what we did, and what we found.

Container removed, exposing fine roots. Some of the media has fallen away and is at the bottom of the wheelbarrow.

Since we can’t see the root flare, we mark the point at which the trunk and soil meet.

As we remove the container media, we find burlap and twine. And under that, a clay root ball. There is a root crown somewhere…

Some beating on the clay rootball helps create some cracks where water can then help with the process.

Into a nice soaky bath to loosen up that clay. The longer it sits, the more clay will slough off.

We speed the process along with a directional spray of water.

Jim gets his fingers into the wet clay to pry it away from the roots. Still no root crown, but you can see the Sharpie line on the trunk a couple inches above the clay.

Eureka! A root flare several inches below the original media level.

After more cleaning and untangling, we have a root system ready for planting. Well, almost.

We have roots, but we still have some problems.

…click on the above link to read the rest of the article…

A Super Simple Salad in Stor(age): A DIY Home Hydroponics Example

October 16, 2021

A Super Simple Salad in Stor(age): A DIY Home Hydroponics Example

Say the word “hydroponics” or the even more mysterious sounding “controlled environment agriculture” and the image that most people conjure in their minds is of large greenhouses or artificially lit rooms filled with complex hoses and tubes using all manner of technological gizmos to pump water and nutrients to plants. True, modern ag technology does allow for some pretty amazing and technical production of food but hydroponics can be super simple and so easy that just about any home gardener can do it.

Why grow hydroponically at home?

Growing vegetables can be pretty easy and straightforward for outdoor production – seeds, soil, water, and wait (sure, there’s a few other steps in there), so why complicate things by growing hydroponically? Aside from the challenge and the novelty that delights many gardeners, intensive growing with hydroponics can allow gardeners with the smallest of spaces to grow impressive amounts of produce in a short amount of time. Most of these systems also do well for winter production indoors with the use of grow lights or some good-sized south facing windows.

Hydroponic or similar-type production systems are the “craze” right now for folks wanting to grow some of their own produce at home, usually in smaller indoor spaces, but these systems can run into the hundreds or thousands of dollars making production less than economical. Plus, most of these systems require the use of pre-made plant/seed plugs that add to the expense.

Why is hydroponic production important?

On a larger scale, hydroponic and controlled environment agriculture has a few benefits that will help in feeding a growing population on a warming planet. Hydroponic production can be pretty intensive, meaning that it can grow a large amount of food in a relatively small amount of space.

…click on the above link to read the rest of the article…

La Niña expected to affect climate around the world by end of year

October 3, 2021

La Niña expected to affect climate around the world by end of year

Do you wish you had a crystal ball that could tell you what the climate will be next year when you plan your garden? So do many other gardeners (and climatologists). But while there is no magic answer, we do know that in many parts of the United States and other countries, year-to-year climate variability is strongly dominated by what is going on in the eastern tropical Pacific Ocean. This is through a phenomenon called “El Niño Southern Oscillation” or ENSO for short.

Witch Hazel Covered By Snow In The Garden. Hampshire UK. Source: Si Griffiths, Commons Wikimedia

What is ENSO and how does it affect climate?

ENSO has three phases—a cold phase with unusually cold water in the equatorial Eastern Pacific Ocean (EPO) called “La Niña”, a warm phase with unusually warm water in the EPO, and the neutral phase that occurs between the two extreme phases. The ocean see-saws back and forth between the two opposite phases on a semi-regular pattern that usually lasts between two and five years from one El Niño to the next. Sometimes you can have two La Niña years (or even three) back-to-back (the end of 2021 is expected to be a second La Niña in a row), but you almost never have two consecutive years of El Niño.

In many parts of the world, the phase of the ENSO is highly correlated with the climate. Scientists can use that relationship to predict what the climate might be like in the coming months. That is helpful for gardeners who need to know what to expect both next season and next year for planning purposes…

…click on the above link to read the rest of the article…

“Save the planet, (learn how to) plant a tree”

September 28, 2021

“Save the planet, (learn how to) plant a tree”

I like catchy memes as much as the next person. They’re easily memorized and passed on. But “Save the planet, plant a tree” has always bugged me for two reasons. First, and probably most importantly, this simplistic mantra absolves people of doing MORE to improve our environment. It’s a “one and done” approach: “Hey, I planted a tree today, so I’ve done my part.” That’s hardly a responsible way to live in a world where climate change is a reality, not a theory. Planting trees (and other woody plants) needs to become part of a personal ethic dedicated to improving our shared environment, and that includes reducing our carbon footprint in MANY ways.

Second, and more germane to this blog, is that most people don’t know how to plant trees (and that includes an awful lot of professionals who should know better). Planting trees properly requires an understanding of woody plant physiology and applied soil sciences. Otherwise, newly planted trees are likely to die due to one or more problems:

Poor plant species selection
- Mature size too large for site.
- Species not adapted to urbanized conditions. This includes insistence on using native species whether or not they tolerate environmental conditions far different from their natural habitat.

*Gaultheria shallon* does well in the forest subcanopy – not so well in urban settings

Poor/improper soil preparation
- Working amendments into the soil before, during, or after planting. Your goal is to keep a texturally uniform soil environment.
- Digging a hole before seeing what the roots look like. It’s like buying a pair of shoes without regard to their size.

The reality of tree roots: you can’t dig a hole until you can see what goes in it.

Pruning Basics

September 18, 2021

Pruning Basics

As we head into Fall garden routines and leaves start to turn color, the smell and feel of the Fall weather is in the air. Winter is just around the corner and with those horticultural routines comes the urge to prune stuff . Both fruit producing and shade producing trees often get a hair cut during fall and winter months, herbaceous perennials are often cut back in the fall after bloom and before their winter rest so it seems a good time to blog about pruning before you get the urge! After years of pruning demonstrations for Master Gardeners and the public I have noted a common thread in how gardeners think about pruning. Pruning is a mysterious process. How we take that tangled mess of a plant (tree) and fix it? What do we prune? And the less frequently asked question: What do we not prune? To add confusion, some plants such as roses seem to have their own pruning “culture”. In this blog post I will cover the basic principles that apply to pruning all plants and then expand into specifics in upcoming blogs.

“Lion tailing” is a form of pruning that removes branches from the interior of a tree leaving tufts of foliage at the ends of branches. This kind of pruning is destructive to oak trees as it lets too much light permeate the crown of the tree

Plants don’t want to be pruned!

The first point is that no plant wants to be pruned. Gardeners prune plants because they think it is necessary for horticultural, aesthetic or safety purposes. Gardeners should temper their pruning by understanding plant responses that result from pruning…

…click on the above link to read the rest of the article…

Everything is chemicals: the myth and fear of “chemical-free” gardening

September 11, 2021

Everything is chemicals: the myth and fear of “chemical-free” gardening

“Chemical-free” – a term I’ve seen several times attributed to many products, especially food and produce at farmers markets and even in gardening circles these days. This term is often misused to describe plants grown without the use of any pesticide, either conventional or organic. I have my thoughts that I’ll share later on that subject but first let’s talk about this “chemical-free” that gardeners, farmers, and others use and why its not only a myth, but a dangerous one at that.

Ain’t such a thing as “chemical-free” anything

At face value, the term “chemical-free” would literally mean that whatever the label is applied to contains no chemicals. That the entire item, whether it be animal, vegetable, or mineral is devoid of any and all chemicals. Factually this can never, ever be true. Everything that exists is made of chemicals. Oxygen, water, carbon dioxide, and any simple molecule, by definition, is a chemical. Plants and animals are organized structures filled with complex chemicals. Even you and I, as humans, are walking, talking bags of chemicals. The air we breathe, the food we eat, and the water we drink are all composed of a great mixture of chemicals. The use of the term “chemical-free” to describe anything is uninformed at best, and intellectually dishonest at worst. But a bigger problem, as we’ll discuss later, is that using the term can cause confusion and even fear of things as simple as food and as complex as science and medicine.

Expert reveals how even natural foods contain chemicals | Daily Mail Online — The “ingredient list” of a peach.
Source

What most people intend to say when they use the term “chemical-free” in relation to plants or produce is that they are produced without use of pesticides or conventional “chemical” fertilizers.

…click on the above link to read the rest of the article…

Xeriscape – landscaping whose time has come.

September 9, 2021

Xeriscape – landscaping whose time has come.

With drought conditions or lower than average precipitation becoming more widespread across the country, it’s time to revisit the principles of xeriscape gardening. Let’s take a look at the “classic” principles and we’ll update them, Garden Professor style.

Note: If you’re growing food crops to supply your table not all of these principles will apply. Some will, e.g mulching, and some won’t. This blog post is focused on ornamental landscaping.

SO WHERE DID IT ALL BEGIN?
As an “official” landscaping technique xeriscaping seems to have begun in the early 80’s. Denver Water, the largest and oldest public water utility in Denver, Colorado, coined the term xeriscape in 1981 by combining “landscape” with the Greek prefix xero-, meaning ‘dry’. The utility then began to formally define the main principles of xeriscaping for members of the Denver community interested in modifying gardening practices to save water. The results were the Seven Principles of Xeriscaping, listed below.

THE SEVEN PRINCIPLES OF XERISCAPING
1. Sound landscape planning and design.
2. Limitation of turf/lawn to appropriate, functional areas.
3. Use of water efficient plants.
4. Efficient irrigation.
5. Soil amendments.
6. Use of mulches.
7. Appropriate landscape maintenance.

Let’s review them and apply some up-to-date gardening information.

1. “Sound landscape planning and design” – the ideal starting point for all gardens, “Right Plant, Right Place.” This principle earns a GP thumbs-up.

2. “Limitation of turf/lawn to appropriate, functional areas” – turf has a place in the landscape but perhaps not everywhere or in every landscape. “Right Plant, Right Place” (hmm, that sounds familiar). Another GP thumbs-up.

3. “Use of water efficient plants” – it may be stating the obvious but you want water efficient plants that work in your grow zone or micro-climate. Do some homework and choose plants that will be happy in your region. We’ll give this one a GP “OK” with a few points lost for being vague.

…click on the above link to read the rest of the article…

Two new climate reports indicate what gardeners may expect in the future

August 30, 2021

Two new climate reports indicate what gardeners may expect in the future

In the past week, two new major climate reports have been released. One is the latest (6^th) report from the Intergovernmental Panel on Climate Change (IPCC) and the other is the State of the Climate 2020 report. Of the two, the IPCC report has garnered a lot more press, but both are compilations of work by hundreds of scientists looking at recent weather and climate patterns and how they are affecting us here on earth. The IPCC report also provides projections of what the future climate might be like, using a number of assumptions about how the earth behaves, which can be difficult, and how humans respond, which is arguably even tougher to determine. In this post, there is no way that I can cover both sets of reports in meaningful detail and I won’t address how we need to address the rapidly changing climate here, but I do want to try to pull out some things that you can use as gardeners now. {Note, the pictures are ones I have taken myself on recent trips to use as eye candy!}

What do the new reports tell us?

The State of the Climate 2020 report, published jointly by NOAA and the American Meteorological Society, focuses on global climate events that happened in 2020. You can read some of the notable findings from the report at my blog. The report also discusses many of the “big” climate events of 2020 and puts them into historical context, including how frequently these extreme events occur and how the changing climate is making them more likely.

…click on the above link to read the rest of the article…

Garden Logic – understanding correlation and causation in our gardens and landscapes

August 21, 2021

Garden Logic – understanding correlation and causation in our gardens and landscapes

*This home landscape is managed using science-based methods; the only routine additions are water and arborist chip mulches.*

Upon reading this post’s title, you may be inclined to stop right there. (That’s why I have an eye-catching photo to lure you in.) While logic may seem irrelevant to your enjoyment of gardening, I can guarantee that reading this blog post will challenge many seemingly logical assumptions you’ve heard or read about. Recognizing unsubstantiated assumptions and avoiding their pitfalls means you can make wise choices about how you care for your gardens and landscapes.

*You can find this and thousands of other silly correlations at www.tylervigen.com*

A few definitions are needed before we get started:

Correlation refers to variables whose changes mirror one another. For instance, the addition of nitrogen fertilizer to container plants is correlated to plant growth: as nitrogen levels increase so does plant growth. You can also have inverse correlation, where the variables move in opposite directions. An example is water availability in soil and planting density: the more plants you have in a specified area, the less water is in the soil.

*Plant growth is correlated with increased nitrogen and other nutrients (from Xu et al. 2020)*

Causation takes correlation one step further: it establishes that one of those variables is causing the change in the other. Using the same examples, we know through published evidence that the increase in nitrogen is causing the increase in plant growth, and the increase in planting density is causing the decrease in soil water because of competing roots. These relationships are obvious to us, but what’s important is that these causative effects have been established through scientific experiments.

*Inverse relationship between planting density and soil water content (from Shao et al. 2018)*

…click on the above link to read the rest of the article…

Counting the Days to Maturity: Calculating planting dates for fall vegetables

August 18, 2021

Counting the Days to Maturity: Calculating planting dates for fall vegetables

While most of the US is still seeing sweltering hot temps, the cool temps of fall and winter aren’t really all that far away for those of us unlucky (or lucky) enough to not live in a tropical climate. The tomatoes, peppers, cucumbers, and other warm-season crops planted back at the beginning of summer are still puttering along, even if they might be getting a little long in the tooth and starting to look a little worse for wear ( especially if disease has ravaged them). For those who aren’t quite done with gardening for the year or who want to reap the bounty of fall crops and get the most out of their production space, fall gardening can be a great tool to extend the garden season. But knowing when to plant what is tricky, especially when we are talking about different weather patterns and frost dates all around the country. So a bit of weather data, info from the seed packet or label, a touch of math, and a calendar can be great tools to figure out when you can plant no matter where you are. Of course if you do live in one of those warmer tropical areas your planting calendar is kind of turned on its head from what us more northern gardeners face. You may prefer to time your planting to avoid high heat.

The first thing to think about is what you can plant. Cool-season crops such as the Cole crops (cabbage, kale, broccoli, etc.), leafy greens (lettuce, spinach, Bok choi, etc.), root crops (radishes, beets, turnips, scallions), and some cool weather loving herbs like cilantro and parsley are all par for the course for a garden going into cooler fall and winter temps…

…click on the above link to read the rest of the article…

Heat domes, wet spells, and the weather patterns that tie them together

August 1, 2021

Heat domes, wet spells, and the weather patterns that tie them together

Do you have a favorite kind of weather that you love to experience? For me, it’s the first warm evening of spring, when the air is just warm enough and the wind just strong enough for the air to feel as though it is dripping off my fingers. On nights like that, I can tell that the air really is a fluid, the topic of this week’s blog.

The wind of spring, Toshihiro Oimatsu via Commons Wikimedia

What causes atmospheric weather patterns?

You may have noticed this year that the weather patterns across both the United States and Europe have been very persistent. That has led to the occurrence of record-setting high temperatures in some locations like the Pacific Northwest and the central US and southern Europe as well as day after day of rain in the Southeastern US. Both of these weather patterns have caused no end of grief for gardeners and farmers, since weather is seldom stuck on day after day of “perfect” conditions (even if you could define what those are).

To understand how weather patterns get stuck, it helps to know how the air moves through the atmosphere. Wind is driven by differences in heating between two areas. That contrast leads to differences in density and pressure between the areas, and the air flows from higher pressure to lower pressure to try to equalize the amount of air between those areas. The large-scale weather patterns across the globe are caused by differences in the sun heating the spherical earth at the equator and at the poles at different angles due to latitude. There are also smaller-scale wind circulations due to differences in heating between land and water (oceans or lakes) that cause the same movement of air molecules…

…click on the above link to read the rest of the article…

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