I am traveling in Colorado this week, so my thoughts naturally turned towards the mountains. Mountains affect gardening in a number of ways, many of which include a weather or climate component. They also provide some special challenges for gardeners because of the harsh conditions and short growing seasons that are often found in and near mountainous terrain.
Red Rocks Park in Autumn, MichaelKirsh, Commons Wikimedia.
How the mountains affect weather and climate
It is said that mountains create their own weather, and there is a lot of truth to that. Mountains interact with the atmosphere in several ways, and that interaction can change both the atmosphere itself and the conditions on the surface of the mountain that is being affected by the air.
If the air is diverted sideways around the mountain it can block the wind from hitting some locations downwind of the peak. Our fearless leader Linda told me she experienced this just a few weeks ago when a strong low-pressure center moved into the Northwest, bringing strong winds to the region. However, Linda noted that in her location, those winds were blocked by Mount Rainier, resulting in much lower local wind speeds due to the shelter from the massive mountain.
Wind flow up and down the mountains due to temperature variations
Mountains can heat or cool the air around them, depending on the time of day and the season. In summer, the peaks warm up and provide a heat source that helps lead to the formation of thunderstorms. You can see this almost every summer day in the western US with storms that develop over the mountains as the sun warms them. Those storms then move out over the prairies, leading to scattered rain or even virga, rain that evaporates before it falls to the ground. At night or in winter, the air near the peaks cools quickly and the denser air flows down the mountains into the valleys, resulting in katabatic winds that can cause freezes in low-lying areas when the coldest air reaches the lowest elevations. In this situation, the valley floors may experience frosts while areas on the slopes remain above freezing because the dense air drains through them relatively quickly. The winds can also increase evaporation rates, limiting the amount of available moisture and causing water stress on garden plants.
Orographic rainfall diagram, Encyclopedia Brittanica, Inc.
Temperature variation with elevation and orientation
The surrounding atmosphere also affects conditions on the mountain terrain. Atmospheric temperatures decrease with height, so as you go up in elevation on a mountain, the temperature will drop. This can lead to cooler climates and shorter growing seasons due to the increased likelihood of frost with the colder temperatures. This limits the types of plants that gardeners can grow because the climate of that location has limited suitability for plants that grow well on the flatlands.
Another aspect of mountainous terrain is the number of microclimates that are present in the rocky, uneven landscape. Mountaintops and sides offer a range of microclimates, from sunny, well-drained slopes to shady, cooler areas, influencing plant growth in different locations. North-facing slopes get little direct sunlight and can pool pockets of cold air that result in frosts every month of the year, while sunny south-facing slopes could be much warmer and more suitable for a variety of plants. Any mountain gardener has to be especially aware of the local microclimates in their area and account for them when choosing what and when to plant.
Alpine garden, Montreal Botanical Garden, Thomas1313, Commons Wikimedia.
Of course, there are other characteristics of mountains that can also affect garden success. Soils are often shallow, rocky, and low in organic matter. Lower pressure and humidity may cause problems with plants’ ability to thrive in the harsher conditions. Sunlight can be very intense and shade from taller plants may be limited. Some areas may experience extensive periods of snow, which can provide insulation but can also damage plants when it slides downslope.
Gardening in the mountains can provide challenges for many gardeners due to the difficult environment that the mountain air provides, but it can also allow gardeners to create unique collections of alpine vegetation that can provide enjoyment for years to come, all set in a diverse and scenic landscape. Be sure to look for additional information on alpine or mountain gardening on the web to make sure your garden is well-suited to your local conditions.
Alpinarium w Bydgoszczy, Pit1233, Commons Wikimedia
Deciphering fact from fiction for one of the most infamous plants in the world.
Dandelion in a lawn. Photo: Abiya Saeed
Dandelions can be a bit of a polarizing subject for gardeners. Some absolutely love them, while others may despise seeing these bright yellow bursts of unconformity in an otherwise ‘pristine’ lawn and garden landscape. Many often find themselves somewhere in the middle of this spectrum. Dandelions are also used as a symbol for resilience–growing despite all odds in some very harsh and unforgiving environments–often ones where few cultivated plants would successfully grow. Some people enjoy eating them, while others embrace them as a source of nectar, pollen, and food for other critters in the landscape. There is a lot of wonder in the way that they disperse, and many kids and adults alike have enjoyed blowing on dandelion seed heads (with or without making a wish) to watch them float away in the wind, drifting to new locations that they can conquer as their own. There is even an annual festival devoted to dandelions in Carbondale, Colorado (located in the same county where I served as an Extension Agent several years ago). When I attended years ago, it was such a cute and unique event, where people were wearing dandelion flower crowns, sharing art and artisan products associated with dandelions, and enjoying music and merriment in the spirit of the whimsical yellow plant. There is a lot of myth, magic, and majesty associated with dandelions, that it can be hard to decipher fact from fiction.
I get asked about dandelions more than any other plant combined– especially pertaining to pollinators, but also many other things. These queries come from people of all backgrounds and viewpoints, ranging from: how to get rid of them, to: how one can encourage and/or intentionally grow and cultivate them. These queries are especially common as spring rolls into Montana with the classic yellow bursts of color being some of the most visible flowers at this time of year, especially in the colder climates of zone 4 in the greater Rocky Mountain region. I have found myself endlessly poring over research to try and answer some of those questions, that I thought it would be fun to ‘dig in’ (pun always intended) to the lore of dandelions and the science-based information that we have on this notorious plant.
The Dandelion
Dandelions (Genus: Taraxacum) are a widespread genus in the Aster family that can be found in most parts of the world, either as a native plant or naturalized through intentional and unintentional introductions. Although there are around 250 species in the genus, the most widespread dandelion species is Taraxicum officinale, also known as the ‘common dandelion’, which originates from Eurasia but is now naturalized in many parts of the world (and can be found on on every continent except Antarctica). For the purposes of this Blog post, I will be focusing on information pertaining to the common dandelion (Taraxicum officinale). This is considered a short-lived perennial plant that can reproduce sexually (through seeds) and asexually (through the roots), can withstand a wide variety of climates and soil conditions, all of which can contribute to the fact that dandelions are so prolific and widespread.
Starting out as a rosette of lance-shaped leaves, it shoots up the characteristic yellow flowers in early spring. Each ‘flower’ is actually an inflorescence that consists of several ray and disc florets clustered together (similar to its relative: the sunflower). The length of the flower stalk is extremely variable, ranging from a couple of inches (in frequently mowed areas such as lawns) to multiple feet in length. I once saw a dandelion curiously poking out through the top of a boxwood shrub that was nearly 3 feet tall, and upon investigation, measured the stalk at a staggering 35 inches (which is half the length of the tallest dandelion stalk on record found in Ontario, Canada). The flowers are followed by the very distinct seed-heads which contain individual seeds, each of which are attached to a fine tuft of hairs (a pappus) that act as a parachute to aid in wind dispersal. Dandelions are well-known for their tap-root which can contribute to the plant’s drought tolerance, and allows them to compete well with other vegetation for limited resources.
The fact that dandelions are edible is not a topic that is frequently debated. Many know this to be true. Almost every part of the common dandelion from the taproot to the flower heads is all edible (with the exception being the stems which contain a milky latex that can be very bitter). Plenty of dandelion recipes can be found with a quick Google search. There is, however, much debate about their taste. To some, dandelions are a whimsical treat, where you may enjoy the flowers or young leaves in a salad, while others choose to steep parts of the plant to make teas, or enjoy the fermented products as delectable dandelion wines. Furthermore, dandelions can be found in many skincare products, salves, lotions, herbal remedies, and more.
In North America, European settlers intentionally brought dandelions for their nutritional and medicinal value. They were intentionally grown alongside vegetable and herb plantings, and used to remedy a variety of ailments. The nutritious properties of dandelions are comparable to salad greens such as spinach and arugula. Leaves are high in potassium, calcium, and iron, whereas the roots can have diuretic and laxative properties. For more information on dandelions as food, check out the link to the publication from University of Wisconsin in the resources.
Although I have yet to find a dandelion recipe that I thoroughly enjoy (besides recipes that try and mask the flavors using in intense array of herbs and spices, or baking them into treats, brewing them into teas, and fermenting them into wines). I am not personally a fan of the bitter and earthy flavor of the raw plant, though I admit, I haven’t tried all variations of cooking or flavoring the parts of a dandelion. If you have a recipe you love and swear by, feel free to share it with me, and I will give it a try (as long as it isn’t too time and resource intensive). Regardless of your taste preferences, if you do choose to eat dandelions, collect them from a safe location, make sure that they have not been treated with any chemicals, and wash them thoroughly to remove any soil, debris, or insects.
Dandelions and Pollinators
Many embrace dandelions because of the associated value to pollinators. The science behind this, however, is not as black and white as some may think. Although dandelions can be convenient sources of pollen and nectar for pollinators in highly urbanized landscapes, especially early in the season when very few other plants may be flowering in some of these densely populated areas, they are not the highest quality source of food for many of our pollinators. Some claim that dandelions are the earliest flowering plants blooming in the spring, which is also untrue in many parts of the world. That being said, dandelions are among the most widespread and consistent sources of nectar and pollen in some landscapes (such as urban areas with fewer flowering plants intentionally incorporated to support pollinators all season long) and also some of the earliest blooming plants visible in these types of landscapes.
A lot of research has been done that shows dandelions attract a wide array of pollinator species, and can therefore be a critical source of food for pollinators in urban areas, where these plants are widespread and can act to bridge the gaps between other areas of more diverse floral resources (Larson et al., 2014). Research also shows that dandelions do not have the most nutritious nectar and pollen, lacking in certain important amino acids, making pollinators (such as honey bees) unable to survive on dandelions alone (Loper and Cohen, 1987). We also know that a dandelion-only diet can impact the ability of honey bees to rear brood (Herbert et al., 1970). Unfortunately, our research is usually restricted to managed bee species such as honey bees, so we have far less information on how most of our pollinator species (including the rest of our 20,000 species of bees) would respond to a dandelion-focused diet. What we do know is that pollinators need a varied diet with floral resources available all season long, including early and late in the growing season when some nectar and pollen collecting species have to begin provisioning their nests and when some species are getting ready to overwinter. Although there are countless flowering plants that are better for supporting pollinators, dandelions will always have a place on that list until more intentional pollinator-friendly plantings are incorporated.
Dandelions can also support caterpillars of a variety of butterfly and moth species. These caterpillars will use the rosette of leaves produced by dandelions as their primary source of food, or as part of a wider diet consisting of a variety of plants. These caterpillars, in turn, can be an important source of food for animals higher up on the food chain (including birds). This can make dandelions important for ecosystems beyond just their nectar and pollen for pollinators.
Dandelions as a Weed
Common dandelions are undoubtedly a resilient plant in many landscapes, as all of us have seen them popping up in lawns, through dense vegetation, in gravel roads and driveways, sidewalks, roadsides, and so on. In fact, it would be difficult to imagine a landscape without dandelions. Because they can grow in conditions that may not favor some other cultivated plants, and therefore may be found taking over areas where you wanted to grow something else, they are commonly considered a weed. In fact, they are probably the most famous weed you can think of, and the poster plant for many lawn care companies, herbicides, and other garden products aimed at controlling or limiting their abundance in our managed landscapes.
Some research shows that dandelions can compete with native vegetation for resources. Research in Japan on native Taraxacum spp. and the impact of growing alongside Taraxicum officinale showed a reduction in seed production for the native species (Kandori et al., 2009). The authors hypothesized that the more attractive flowers of T. officinale may deprive the native species of pollinators, resulting in a reduction of pollination services. They also stated that the transfer of pollen from the non-native species could interfere with the successful reproduction of the native species, however, this was disproven by hand-pollination experiments (Kyogoku, 2021).
In many home garden settings, whether or not something is a weed, is usually very subjective and dandelions are no exception. I, personally, don’t mind dandelions growing opportunistically in my landscape, and my stance on many persistent (non-noxious) weeds in the garden is usually a variation of ‘may the best plant win’, but I know that not everyone feels this way. Although some embrace the odd dandelion speckled in a lawn, when you have large swaths of dandelions in the place of what used to be turfgrass, the problem usually extends beyond dandelions themselves.
One of the best ways to combat dandelions in a turf lawn setting, is to make sure that your turfgrass is healthy and able to form dense coverage on the soil. Healthy turf can often outcompete weedy vegetation that can opportunistically take advantage of open spaces for establishment. Addressing soil compaction, nutrient needs, and responsibly caring for your turf lawns can all play a role in reducing weed issues, including dandelions. For situations where competing vegetation may not be an option, mulches can be used to reduce the presence of dandelions that may be found in flower beds or veggie gardens. Mechanical removal is also very effective for controlling dandelions, depending on the scale of the issue. Using your favorite tap-root removal tool (such as the aptly named dandelion fork) can remove plants without too much exertion. Pulling out as much of the root as possible will offer the best control, as dandelions are less likely to propagate from smaller root fragments.
Several herbicide options are also available for dandelion control. Broadleaf herbicides such as 2,4-D, dicamba, and MCPP (commonly found in ‘weed and feed’ fertilizer products) can be effective for dandelion control in lawn settings. Spot-treating individual plants using an appropriately labeled broadleaf weed killer is usually more effective than broadcast application across larger areas. Herbicides with the active ingredient Glyphosate are not as effective for long-term control of perennial weeds like dandelions, because they often knock back leaves without killing the roots, which allows the plants to regenerate. These products can be more effective if a plant is cut or mowed and the herbicide is carefully painted on the fresh cut, which can facilitate movement into the root system. Late summer and early fall is the best time to control perennial weeds such as dandelions. This is because these plants are moving resources from the foliage to the root system in order to prepare for winter, which can also help to transport systemic herbicides to their roots and/or deplete their root systems of energy for more effective and longer-lasting control. (Remember that herbicides may kill desirable plants, and not just weeds- so use them responsibly and sparingly while taking precautions not to apply them near susceptible plants). Always, always, always read and follow label directions, and if unsure: reach out to your Extension resources for assistance.
Whether you are a big fan of dandelions, or the opposite of that–I hope that you learned something new from this post–and continue to be curious about the plants that surround us!
Larson, J. L., Kesheimer, A. J., & Potter, D. A. (2014). Pollinator assemblages on dandelions and white clover in urban and suburban lawns. Journal of Insect Conservation, 18, 863-873. https://link.springer.com/article/10.1007/s10841-014-9694-9
Herbert, E. W., Bickley, W. E., & Shimanuki, H. (1970). The brood-rearing capability of caged honey bees fed dandelion and mixed pollen diets. Journal of Economic Entomology, 63(1), 215-218. https://academic.oup.com/jee/article-abstract/63/1/215/798721
Kandori, I., Hirao, T., Matsunaga, S., & Kurosaki, T. (2009). An invasive dandelion unilaterally reduces the reproduction of a native congener through competition for pollination. Oecologia, 159, 559-569. https://link.springer.com/article/10.1007/s00442-008-1250-4
