Of Hell Strips and Seeds

Casa Del Rey Site Development

What do you do with that annoying strip between the sidewalk and the street? In our modern neighborhoods this question is perplexing to city planners, homeowners, and pedestrians. It’s too small for much of anything and the perennial  solution to its perplexing nature is to fill it with sod. This means that it has to be watered, mowed, fertilized, and kept alive with dogs, humans, and the odd car driving over it. For its location near the street and all it has to handle, this small strip is affectionately referred to as the ‘hell strip’. It is both difficult to keep flourishing but also requires resources people want to use in other places. Is there a better solution? Could our urban and suburban neighborhoods find a different way to handle this ubiquitous but odd strip of space?

We think there are better alternatives and we are trying one of them out at a condominium HOA in downtown Denver. Casa Del Rey, an art nouveau-styled condominium building, reached out to Tree of Life after seeing our work on an adjacent property. They are in a beautiful location near Cheeseman Park and right across from the Denver Botanic Gardens. Wanting to honor the botanical focus of the neighborhood and wanting to save on water, the Casa Del Rey residents sought a design that would do both of those things as well as an update to the landscape from the tired foundation plantings of junipers and shrubs. 

We wanted to honor the design of the building and keep the plantings near the building more formal in style, a nod to symmetry and structure, but using well-adapted plants that thrive in our climate. But… Casa Del Rey has a large hell strip - nearly 15 feet wide - and it was planted with sod. The sod was struggling, both from foot traffic and established catalpa trees that sucked up the water with their hungry roots. What could be done here that did not require huge amounts of money and stewardship but would thrive (the sod was in sorry shape)? 

Our solution in one word was… SEEDING. What is seeding you may ask? Well, literally broadcasting seeds to establish a plant community from seed. Of course, this seems so very simple but complex seed mixes to address urban concerns is a new and fast developing field. James Hitchmough and Nigel Dunnet, professors of landscape architecture in England, are the leaders in the field with their groundbreaking book, Sowing Beauty. They argue that plant communities can be established by seed in a way that allows the planting to develop over time and also, most importantly, to repair itself. If the mix includes the right amounts and types of flowering perennials, annuals and grasses, the planting can become a self-perpetuating system. When there are holes, the high-seeding annuals can drop their seeds and send up another generation of baby plants. When the sunlight changes, the plants that appreciate a little more shade can fill where it was once full sun plants. 

One major factor in favor of seeding is that it is far cheaper than doing anything else, even rock. People in Colorado tend to think that the easiest solution to open dirt is to fill it with sod and if not sod, then rock. Problem solved. But it isn't. Rock is expensive and after a year begins to fill with dirt which then grows weeds again. The only solution for keeping rock looking clean is herbicide applications. If we could fill your inbox with pictures of weedy rock, trust me, it would be full to bursting. Seeding is cheaper, benefits the urban environment, supports pollinators, fights weed infiltration, and with careful planning, keeps itself looking good for years to come. 

Grab the vision! Watch this seeding progress as you walk by and then take a look at plantings from seed in the neighborhood:  Josephine Street designed by Kevin Williams and the Congress Park seeding designed by Michael Guidi. Sowing Beauty is possible and a fantastic solution for those hell strips in your life. But don’t stop at the hell strip, try seeding areas that could use some beauty. You’ll be surprised by the serendipity that surprises you and the beauty that enfolds you.

What Is A Weed?

Often when we talk about “weeds” at Tree of Life, we try to use the term “misplaced plants” instead, sometimes getting a look or two. We do this for a couple of reasons. First, we want to remember that these misplaced plants are part of an ecosystem somewhere, even if it is Europe or Asia. We also want to remember that sometimes weeds can be native, and just because we didn’t put them there, doesn’t mean that they can’t be there. By using more precise language we can say that this is a plant we don’t want in our garden without putting it into a category of “bad plants”.

Especially with seeded meadows and other ruderal (plants that spread mainly by seed) gardens, it’s important to maintain balance to keep one species from taking over. Sometimes the same plant can be a weed in one garden but not in another and since it is hard to tell which plants should stay and which should go, we came up with five criteria to help guide our garden stewardship. 

A wild Sweet Pea grows over a commercial fence in Mead, CO

Do I like it?

Some plants have been put into the weed category, and we pull them out without stopping to ask ourselves if we like it. Beth Chatto famously used biennial thistles in her gravel garden, showcasing their cactus-like beauty. If a plant is a “weed” but we like the bloom, texture, color or some other element, it is often ok to let that plant thrive. Some plants like Mullen, Scotch Thistle and even Bind Weed have features that we may consider desirable in our gardens. Bind Weed was once considered a wild Morning Glory that could act as a ground cover, though I do think it’s ok to pull this one every time. Other plants like Sweet Peas or Milkweed are some plants that may self-sew in our gardens and provide some unexpected beauty.

Erigeron canadensis or Horseweed is welcomed into this naturalist planting

Is this plant displacing plants that I would rather have in my garden?

If this plant is going to make it harder for some of our preferred species to thrive, it is probably best to remove it. Things like bind weed, kochia, or mallow weed are fast-growing and can easily out compete our perennials. Sunflowers can even out-compete smaller plants with its large leaves and fast-growing habit. Though they may be small at the moment, they can quickly become a garden bully with their fast and competitive growth patterns. 

Dandelions are quick to take advantage of unused, disturbed soil

Will this plant cause a larger problem in a year or two?

Sometimes inviting one plant into our space can result in a whole colony in a year or two. Species like Mullen or Biennial Primrose will produce thousands of seeds at maturity that could result in a hostile takeover of the garden. For this reason, it is important to understand these plant’s lifecycle, so we can prevent them from becoming a problem in the garden. Volunteer tree sprouts likewise can be quick to sprout and can quickly become a larger problem if you don’t want a tree there. Other plants like Smooth Brome or Bindweed can spread by seeds, rhizomes or stolons and can slowly encroach on our gardens.

Kochia will create a dense monocultural carpet if allowed to reproduce

Is this plant good for pollinators?

Some unwelcome plants bloom in the early spring before many of our perennials, providing a valuable food source for pollinators. Even though Dandelions may self-sow into our yards, inviting diversity into our turf lawns isn’t always a bad thing. Plants like Dandelions and Blue Mustard will bloom as early as April, taking advantage of the spring moisture. Leaving these plants in our spaces can help support honeybees and native pollinators in the early spring. 

Dandilions and Blue Mustard create dense blocks of color and support pollinators in the early spring

Is this plant protecting the soil and locking in moisture?

 In some instances, species like spotted spurge or purslane will quickly cover bare spots in the soil. Sometimes these low-spreading species (especially Bind Weed) keep other plants from reaching full size, but by covering the soil they retain moisture and prevent soil degradation and compaction.

Diverse plants such as Hoary Cress, Blue Mustard, London Rocket and Smooth Brome cover this area that might otherwise be Kentucky Bluegrass or rock

When Is The Appropriate Time To Cutback?

Finding the right time to cut back grasses and perennials can be a difficult task, especially when considering the impact on local wildlife, plant health and maybe even what your neighbors think of your garden. With nearly endless rules and opinions, we wanted to put together a few important considerations when scheduling your spring cutback.

Leaving the remains of our gardens through the winter is not only great for pollinators and insects but it is beautiful! In Colorado, the skeletons of our summer plants form the texture and color of winter gardens. At Tree of Life, our gardens are designed specifically for winter interest. Colorado affords us the right climate to enjoy the varied colors of winter. Leave your gardens up and provide habitat for nesting wildlife and enjoy the beauty.

When it comes time to cut back your space, consider the following points and see what best fits your unique situation.

Pollinators and Stem-Nesting Bees

Many of us know that leaving the skeletal remains of the summer’s perennials and grasses provides important winter habitats for insects, but stem-nesting bees need habitat through the summer as well. These insects will lay their insects in hollow stems in the spring and the larvae will remain there for the whole summer and emerge the following spring. For this reason, The Xerces Society recommends leaving 24 inches of stems that are suitable for stem-nesting bees and cutting them down every other year. This may look different from a traditional cutback, but the spring growth will soon cover the remaining stalks. If you are trying to prioritize habitat for stem-nesting bees, we recommend this type of cutback, especially for these species: 

• Monarda sp. 

• Rudbeckia sp. 

• Echinacea sp. 

• Solidago sp. 

• Aster sp. 

• Symphyotrichum sp. 

• Asclepias sp. 

• Agastache sp.

• Hydrangea arborescens
  

Gravel Gardens 

For gardens with a gravel mulch, you will want to cut back all grasses and perennials and remove the biomass to avoid adding another layer of soil over the rock mulch. We like to remove this plant matter and compost it separately. You can add the compost back into the soil when adding plants to your garden.

Don’t Forget Ephemerals 

For many of us gardeners, spring ephemerals are the first blooms of the garden and we don’t want the old plant material to obstruct our spring crocuses. Myself, a gallanthophile, I never want to damage my snowdrops by cutting back later in the season. 

Mow and Mulch

If you know that the species in your garden can withstand a spring mow, you may be able to simply mow and mulch the entire garden. Cool season grasses like Helictotrichon and some warm season grasses like Sporobolus heterolepis can suffer if their crown is scalped by a low mow, so it is important to know which species may require additional attention.

Grazing 

We often separate Flora and Fauna into different natural systems, but an ecosystem in equilibrium must include both. Ungulates (grazing animals) that once roamed the plains would graze and trample the prairie, essentially doing our spring cutback over the winter. If you have access to grazing animals like cows, sheep or pigs, allowing them to graze is probably the best option for cutting back our plants. Too bad it is not an option for most of us!

Fresh Baguettes and Healthy Soil

Fresh Baguettes and Healthy Soil

By Johnny Moore

Prairie diversity above and below ground. Image Source: Tall Grass Prairie Center

January 15, 2024

Soil, like a baguette, is little more than a few raw ingredients mixed together: minerals, living and decomposing organisms, water, and air. But a fresh baguette in Paris, though made from simple ingredients, is far from simplistic. The same is true of healthy soil. A baguette is the masterful suspension of flour, water, and salt, shrouded in an idyllic crust, wrought by the living organisms of yeast and the hot air of an oven. The well ordered ingredients produce a work that is nothing shy of beauty and harmony. An authentic, French baguette, eaten fresh, is irresistibly delicious, nourishing to mind, body, and soul. It is magical.

While it’s rather easy to care about a good baguette, who cares about the soil? Just sprinkle on some fertilizer and things should be fine, right? If there is a weed here or there, just apply the right herbicide and you will be set. What more is there to it?

By the same token, we could scrap baguettes and just eat power bars, chocked full of all the essentials. Eat nothing but your favorite power bars and it doesn’t take long to miss the magic that food like baguettes offer. We desire more than the perfect ration of vitamins and nutrients delivered to us in a compact, scant, industrialized bar. We long for real food.

If you’ve ever tried to push a shovel into rock hard clay, or questioned why your tomatoes developed a blight from the soil, or why your grass is turning brown even though you’ve been watering it twice a day, the answers likely lay in the health of your soil.

Like a baguette, healthy soil can be magical–causing plants to grow and thrive, being easy to dig, free of weeds, and absorbing water like a sponge. However, as the raw ingredients of a baguette need a baker to proportion and bake them, the soil needs its many members to order and organize it. Without those processes in action, we are left with the stubborn, raw ingredients, unyielding to our shovels and unhelpful to our tomatoes. Who are the bakers of the soil world? It turns out there are more than we have yet been able to classify. 

In healthy soil, the raw ingredients are orchestrated and processed by innumerable microscopic life forms. These microbes take the raw ingredients of decaying biomass (dead plants, leaves, trees, etc.), minerals, water, and air, and bake the stuff we love and call topsoil. These “bakers” are bacteria, fungi, plant roots, and even animals. They take the raw ingredients in the soil and transform them into life-sustaining, bioavailable nutrients (think baguettes!) for one another and plants. Left to themselves, most minerals and elements are not in a form usable by plant roots and organic matter breaks down incredibly slowly. Plant your tomatoes in rocky or heavy clay soil, and though rich in minerals, your tomato roots may struggle to break down the rock and clay to access and take up the phosphorus, potassium, or nitrogen the plant needs to produce delicious fruit. Plants need the raw ingredients turned into a bioavailable form.

As we know, plants transform sunlight and carbon into organic matter. Plants convert the solar energy and release substances through their roots known as exudates–organic compounds which attract and help foster various bacteria and fungi in the soil. Those bacteria and fungi are the bakers and doctors, feeding the plant the nutrients and medicines it needs to grow and fight off pathogens. This is the beginning of what’s known as the soil food web.

A plant in need of phosphorus secretes root exudates attracting bacteria that can make phosphorus bioavailable to that plant. The bacteria form a relationship with plants which feed them; the plant receives the nutrients it needs from the bacteria while the bacteria feast like kings. As the bacteria thrive, they become the food supply for other soil organisms: bacteria are eaten by protozoa, protozoa are eaten by nematodes, nematodes are eaten by arthropods, arthropods are eaten by birds and small animals. The entire food chain is supported by plants living in the soil.

Vibrant and full of life, healthy soil becomes sponge-like, able to absorb inches upon inches of rainfall, staving off erosion, drought, and flood. Contextualized plant communities are then able to thrive, support themselves and the surrounding ecosystem without supplemental irrigation or fertilizer inputs and with minimal stewardship management. And just as with baguettes, the world of the soil, freshness and abundance, becomes a beautiful and magical place. 

2023 Plants of the Year

By Michael Erickson

December 6, 2023

With plants at the forefront of most of our designs at Tree of Life, a select few always stand out to us at the end of our planting season. We are constantly looking for new species and cultivars to utilize in our designs, and we wanted to share our top five favorites from the past year. 

Eragrostis spectabilis

One of our favorite grasses to use this year, Eragrostis spectabilis or purple lovegrass is a gorgeous warm season grass, with a vibrant purple inflorescence. Tolerant of a variety of conditions including drought and heat, Eragrostis thrives in many native inspired and xeric gardens, offering a native and earlier blooming supplement to Muhlenbergia reverchonii. With such a delicate seedhead, its smoky texture billows when planted in droves and feathers into its surrounding plants. Given its aptitude for the Colorado landscape, it readily self-seeds to fill in empty spaces in the garden without displacing the less competitive plants. Altogether, Eragrostis spectabilis is well-equipped for our climate, it has a dynamic growth pattern, and provides a delicate but colorful texture to the garden. 

Artemisia abrotanum ‘Leprechaun’

Texture is a key piece in our designs and the discovery of the Leprechaun Artemisia has provided us with a great new texture that will thrive in multiple conditions. It is dense and compact, with a lime green color and a feathery, fearn-like texture. With tree growth, garden maturity, or general change in the garden, we want to use plants that will thrive even if their conditions change and the Leprechaun does just that. With its rigid form, we have utilized this artemisia as a structural element in our designs, similar to that of a boxwood without the water requirements. Tolerant of sun and shade, and low moisture, we look forward to seeing it mature in our gardens from this past year, and to using it in designs in the coming years.

Atriplex canescens

Sometimes referred to as Chamiso or Fourwing Saltbush, Atriplex canescens is a true native to the great plains. With an ambiguous form, Atriplex may grow low to the ground and spread, or may remain more compact and take a traditional shrub form. Silvery foliage throughout the growing season produces fruits that have four wing-shaped seeds giving Atriplex its common name. We love its unique seed head and irregular growth pattern and have used it intermingled with shorter grasses. Tolerant of a variety of soil conditions especially high-stress areas and requiring very little water, Atriplex is a staple plant for high stress and low water environments. 

Dalea purpurea

Year after year we continue to be amazed that Dalea purpurea or Purple Prairie Clover is a native plant and not cultivated specimen with its bright purple thimbles and fanciful appearance. Prairie flowers are often considered insignificant or underwhelming, but Dalea purpurea packs a punch in its relatively modest form. Growing in a vase shaped form, exploding into fluffy purple puffs. Beyond floriferous interest, Dalea purpurea’s foliage is needle like, offering textural interest even before its bloom mid summer. Blooming around the same time as Asclepias tuberosa, we love the intense variation of color and form.  As a member of the Linaceae family, a long taproot and mycorrhizal fungi below the surface increase the soil health of the landscape. 

Liatris ligulistylis

Yet another rather flamboyant prairie plant, L. ligulistylis, sometimes called Meadow Blazing Star, maintains all the features of the genus but its flowers are much more conspicuous than its other native cousins like L. spicata. Growing up to five feet tall, bright fuchsia spikes stand out not only to us, but also and especially to butterflies and pollinators. We love utilizing this liatris as a strong vertical accent in our gardens, towering over shorter perennials.  A vibrant and floriferous native plant, this Liatris brings height, dimension, and fun to many of our designs.

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