Garden Designers Roundtable: Get the Weeds Out!
Possibly the least glamorous task for a gardener is weeding. Weeds are the blemishes on the otherwise beautiful complexions of our landscapes, but unless the gardener pays attention to these unsightly and tenacious plants, our gardens will be lost to them. Taking the time to thoroughly comb through our desirable plants for thistles, dandelions, and little buckthorn seedlings is essential to the beauty and longevity of our gardens. One pesky plant that many Midwestern gardeners are fighting right now is garlic mustard (Alliara petiolata.) It is a rampant invader of mostly woodland areas, but it tolerates sunny sites, too. It is a biennial, but the fact that one plant can produce between 350-7900 seeds translates into rapid spread. Patches can spread an average of about 20 feet per year, expanding as much as 120 feet in one year. When established, garlic mustard becomes a permanent member of the plant community, often dominating the ground layer habitat over extensive areas. Prior to seed production, flowering garlic mustard plants can easily be pulled and soil removed from the roots. Plants should be disposed of in a compost facility for invasive plants or left to decompose on site in an area that they will dry out and not re-root. If plants are discovered after seed production, the area shouldn’t be entered to avoid spreading seed, but that area should be weeded carefully the following spring. Large infestations of garlic mustard can also be treated with a 1.5% solution of glyphosate, if desirable plants are not at risk.
Once garlic mustard plants are removed from an area for successive years, and it is believed that the population has been eradicated, it is key to cover the bare ground with hardwood mulch to prevent erosion and limit further weed establishment. Appropriate plantings for the site will also prevent erosion and help to reestablish the native plant community preventing future weed invasion.
One benefit of garlic mustard appearing in your landscape is that it is an edible plant and actually became a weed after it escaped cultivation in the U.S. The young greens can be used as a garlicky herb in butters, sauces and pesto, and salsas.
Spring has sprung at the Demo Garden
A Spring Progression of Trees for Garden Design Round Table
By Douglas Owens-Pike
What is the value of a tree? A new website helps you determine what specific trees around your home are worth: National Tree Benefit Calculator. This leaves me a bit cold. The dollar amounts seem so modest given what I feel for trees we have planted and nurtured. Some say the cost of planting a tree yields at least three times as much in direct benefits. These include: oxygen we breathe, cooling shade, blocking winter winds, filtering out air pollution, reducing noise, perfuming the air with blossoms, massive yields of edible fruit or nuts, and locking up carbon dioxide to reduce the impact of climate change. Adding to that list: important habitat for insects and birds, reduced soil erosion, and more reliable stream flow during the drier months. Finally, healthy, mature trees improve both appearance and price of homes for sale.
As alluded to above, there are perhaps even more important emotional attachments we feel for trees than seeking a dollar value. The trees we plant are similar to offspring. We guard them through their early years, providing more support and care helping them grow toward closer to maturity, fending off danger, and gently guiding them with selective pruning. Trees have been shown to reduce violence in urban settings. There is less crime in developments with trees and landscaping than similar adjacent buildings dominated by pavement and litter.
One advantage of living in Central Minnesota is our long summer days. While we have not had many days above 80 degrees we are seeing long periods of dusk as the sun rises in the NE and sets in NW. Instead of 8 hours of direct winter sun, we are now closer to 15 hours each day. Our local trees, except for evergreens, have adapted to these seasonal changes by gathering all their energy from the sun in these few months of May through October. We see their quick flowering and leaf emergence in this season.
Some of my favorite trees include: bur oak, trembling aspen, hackberry, red maple, black oak, swamp white oak, shagbark or bitternut hickory, and locust. Evergreens efficiently block setting summer sun and winter winds out of the northwest include: white pine, Black Hills white spruce, and eastern red cedar. White cedar has tremendous beauty, but is not drought resistant. Trees for raingardens include: swamp white oak, river birch and alder. Understory trees that withstand some deer browsing include: ironwood and blue beech/musclewood. Two more understory small trees, that require some protection from deer and rabbits are serviceberry and pagoda dogwood. Three small trees that thrive in the woodland edge or savanna habitat are fragrant sumac, wafer ash and wahoo (a great large shrub to replace the European burning bush of the same genus).
Trees to avoid: all ash species due to introduced Emerald Ash Borer, Russian olive, buckthorn (both glossy and common), Amur maple and the shrub Tartarian honeysuckle.
Look for a future blog entry on where to place trees and shrubs for the best energy benefits year-round. Computer modeling of shade patterns by season reveal that due south of your home can be the absolute worst place to install a new tree. The best time to plant trees is close to Labor Day to give them several months to expand their root systems before the next hot, dry summer. Often, trees come from the nursery with several inches of soil placed on top of the primary tree roots. You will know you have the proper planting depth if you can see the trunk begin to flare. If the young tree has a diameter that does not change at the ground you should remove the potting soil until you find those primary roots.
Check out these other awesome Garden Design Round Table entries on trees:
One way to beat ‘em is to eat ‘em!
My 15-year professional life in natural areas restoration and native plant landscaping has included a fair share of managing/treating/removing and generally hating invasive species. I have a visceral reaction to a solid patch of garlic mustard or the pink hue of a wetland invaded by purple loosestrife. All too often, my skin has been stained by an errant buckthorn berry making its way under my collar. There is no love lost between me and a waving field of reed canary grass.
Though, fighting these tenacious plants and animals is a lesson in perseverance and adaptability. Some folks have taken their adaptability to a whole new level. Check out this MinnPost article on a rather positive approach to these overly abundant plants and animals.
Inspiration for Garden Design Round Table
One of my great joys in life is spending time in nature. I find this is the best way for me to be recharged and inspired to solve the many riddles we face as landscape designers. Studying how plants, rock, water, and sky combine in a place with little human disturbance gives me the best clues to move forward with design details. This includes land shaping to move water. Transforming it from a waste, where it is not needed, to a resource, where it gently soaks into the soil, providing long-term benefits to nourish those plants as well as recharging that watershed.
- Raingarden at work
This knowledge from nature helps me discern proper selection of plant diversity that, when added back into a highly disturbed site, will thrive with only minimal care.
Years ago, I had the pleasure of backpacking through the Olympic Mountains in mid-summer. There was plenty of snow still melting in July. On one south facing slope, covered with fine rock scree sliding down the steep pitch, we hiked through a stunning display of wildflowers. There were masses of color all artfully arranged by a designer who knew how to hold back this temporary moisture, and ensure a gorgeous display of blooms to attract the essential pollinators. Without them there would be little viable seed. Of course, we were in the middle of a million acre wilderness.
This designer was the time required for colonization and succession ever since this valley was full of glacial ice ten thousand years ago. The natural process of selection guided an assemblage of plants that could thrive despite a short growing season, freezing overnight temperatures even in mid-summer, and other stresses we rarely face as garden designers.
Now, when I recall that mountain slope, it is my dream to recreate as much beauty when faced with urban challenges of hot pavement and walls, drought followed by floods of runoff, winter deicing chemicals, trampling by pets or people, and grazing by too many rabbits and deer. Natural settings give me the inspiration to create a community of plants that can stand up to comparable challenges and stresses. Taking time to find settings where plants have evolved to handle similar conditions is a key to successful urban ecological restoration.
Nursery growers inspire me. Those experts who are able to harvest seed from plants adapted to these tough conditions, get them to germinate, and grow seedlings up to a size that are viable when we transplant them out into our projects. Without their expertise we would not have the diversity of species to choose from when we are planning our roof top meadows or raingardens.
Educators inspire me. They are the wondrous few who have the special ability to translate their understanding of plant ecology, landscape design, and construction techniques; and then communicate those ideas in books, lectures and projects they design and install to inspire us to go beyond what we had thought possible. I am grateful for all these ways I’ve grown, and will continue growing, as an ecological designer.
Please follow these other links to other Garden Designers Roundtable blogs and hear how other designers have been inspired.
MNLA’s Scoop features article by Douglas
The January 2013 issue of the Minnesota Nursery and Landscape Association’s “The Scoop” Magazine features an article by Douglas Owens-Pike. The article focuses on the changes we will encounter in the economy this new year, and how sustainable and cost-efficient landscape design responds appropriately to these new challenges. We can improve our profits as we learn to create landscapes that are more resilient and beneficial to the environment.
“The Scoop is MNLA’s monthly magazine that provides insights and information for green industry professionals. Mailed to approximately 1,900 addresses and sent via email to 2,500 addresses, it is the most widely read, locally-written, green industry trade publication in the region.
“The Scoop is MNLA’s flagship publication, delivered to all association member companies. If you’re the employee of a member company and would like to receive the e-version of The Scoop each month, please email Jon Horsman” at email@example.com
Last Minute Winterizations
1. Leave the Leaves. It’s likely that you already picked up most of your leaves in your yard. If not, please don’t! At least, not in your garden. The leaves are a great way to help insulate plant roots and provide biomass for natural decomposition. The leaves will break-down in the garden creating compost the way nature does in forest. In spring, you can add a light layer of mulch to cover leaves if you prefer.
2. Don’t Dead-dead. Removing the dead vegetation on a flower/plant at the end of the season (dead-heading) is a common practice among gardeners. However, these are the winter homes for many beneficial insects that live in your garden. Many insects spend the winter in immature stages – as eggs, larvae, or pupae (the large silkworm moths such as the Cecropia moth). Some insects spend the winter as an adult (lady bugs and mourning cloak butterfly) seeking out a protected spot to lie dormant until the weather warms again. Your dead garden stalks are ideal places for all these life stages to shelter during the harsh MN winter. Plus the stalks and seed-heads create winter beauty for you to enjoy. Cut the stalks back in late spring when the insects have had a chance to warm up and come back to life.
1. Water your trees. Watering trees, especially evergreens right up until the ground freezes, is the best thing you can do to protect against winter injury. Evergreens are dormant during the winter like deciduous trees, however, they can loose moisture from their needles in the winter winds.
2. Mulch your trees. A good 6-8 inches of wood mulch will insulate roots from the extreme temperature changes that can occur in winter due to solar radiant heat. The sun will heat up the soil surface during the day, but temperature drop dramatically at night. These temperature swings can kill new roots. Create a large mulch ring around trees by placing biodegradable weed barrier in a circle around the trunk (the larger the ring the better for your tree!). Then add 6 inches of wood mulch on top the paper (do not put any mulch up against the trunk of the tree to prevent stem-girdling roots from forming).
3. Wrapping your trees. Young trees and trees with softer woods (e.g. maples) are prone to Frost crack and Sun scald. These are terms for a deep crack forming along a tree trunk due to the temperature changes that can occur in winter due to solar radiant heat. Again, the sun will heat up a tree trunk causing different tissues to expand or contract. The result is a big crack in the trunk of the tree. To prevent sunscald, wrap the trunks of young trees with light colored tree wrap (don’t confuse it with burlap). This material helps to insulate the trunk from the excessive warming effect of direct sunlight. Wrap the trunk in late fall, and remove the wrap in early spring.
Weather you have our popular “No-mow” fescue or a regular turf lawn, removing leaf debris is essential to ensure the turf survives. Leaf debris is great on the garden, but it can smother and create dead spots in a lawn. Rake the leaves to your garden, compost bin or mulch them up with a mulching lawn mower.
PONDS AND WATER FEATURES
Cleaning up your water feature is best done in fall. Taking this time to clean filters will prevent the debris from becoming dried and difficult to remove. Vacuum all dead and decomposing material in lined ponds to avoid algae bloom come spring.
Native Plants, Our Future
Native Plants, Our Future
Garden Design Round Table
Written by Douglas Owens-Pike
We are blessed to be present during one of the greatest upheavals in nature during the several billion year history of this planet. Blessed, because we have the opportunity to make a difference. Mounting evidence shows that we either change our habits and move toward more sustainable fuels (probably not corn ethanol), or the massive redistribution and possible extinction of the plants and animals we depend on for food, as well as native plant communities, will be upon us. The shift in rainfall from the breadbasket of North America further north this growing season could be a glimpse into a hotter planet. Some theories suggest that this shift is a result of less ice covering the Arctic Ocean which in turn may be forcing the jet stream to guide rainfall north.
What does this ecological upheaval have to do with landscape design? Let’s begin with trees. Trees are one of the primary ways we can cool our planet and make outdoor living spaces more comfortable in the face of increasing heat. Unfortunately, in recent history, many regions of the United States have suffered from tree decline due to the combined forces of introduced insects and diseases together with the stress of mixed up weather patterns. Trees should live for several human generations, if we pick the right species. Right requires some understanding that our future climate will probably be quite different from what we have known. As an example, here in Minnesota, we have a tension zone that separates the prairie region of the SW from the northern hardwood forests of the NE. The current expectation is that this boundary will shift from the center of our state to the farther NE corner. In light of this boundary shift, we should think about planting trees that will prosper in this new, hotter, and probably more drought ridden climate. What choices do we have? We can begin with native trees usually found on the edges of drier habitats: several oaks come to mind as well as hackberry. Additionally, Boxelder which is normally thought of as a weed colonizing bare soil, could be ideal for some areas.
Underneath these trees we can plan for greater heat and drought stress by adding shrubs that meet our landscape priorities: screening for privacy, flower color, attractive fruit, and food for people or wildlife. Hazelnut, wahoo, snowberry, and others fit these criteria.
Ground layer can include plants that require little fossil fuel for care like sedges and fescue grasses that stay short without mowing. Flower beds can be attractive native meadows planted with an eye focused on the soil, sun and moisture available. The good news is that smart landscape design allows each of us to install landscapes that help reduce carbon emissions by storing them in long-lived perennial roots, as well as tree and shrub wood above ground.
Water is already a scarce resource on much of the planet, and we might want to plan on it getting more expensive here. If you irrigate your gardens, switch to low water use drip lines to prevent the high levels of evaporation that occur when we spray water into the air. Of course, with the right collection of native plants you will need no irrigation, except immediately following installation.
How do we determine the right native plants? Formerly, we looked to surrounding communities of native plants. While this approach still holds true, we will need to begin focusing on similar species from farther south, up to 200 miles even, of where we are designing. Many plants cannot evolve fast enough to compensate for changes to our growing season. Research has shown that people need to get involved if we are to save even a tough, native annual like partridge pea, Chamaecrista fasciculata. It thrives in desert-like, moving sand habitats from Gulf states to Canada. Yet, if you plant seed from Minnesota in Texas or the reverse, it will not survive. By going just a few hundred miles it seems to be just about right for the changing conditions. Normally, this annual disperses its seed up to 10’ by twisting its drying pods. Others move further, carried by water, but only people can move this seed north fast enough.
If you have been focused on horticultural varieties for your landscape designs, consider adding native diversity to your pallet. While doing that, look several hundred miles south of your location for inspiration. By doing so, these thoughtful landscapes will help some native plant diversity survive the changes ahead of us.
Thanks for reading!
To learn more about designing with natives, please take a moment to read the thoughts of other members of the Garden Design Roundtable:
Garden in Bloom
This Thursday begins the Great Minnesota Get Together! Yes, it’s time for the state fair already and in Minnesota that means the end of August, and school-less summer, is somehow upon us. But, summer is leaving us with some tremendous blooms and harvests to remember her by. Here are some shots from our small demo garden near the office. Notice the 7-foot-tall-and-still-growing Cup plants along the south wall of our building. These giants, together with their smaller colleagues, have managed to soak up much of the summer sun and reduce the temperature of our building between 5 and 10 degrees. They’ve all been excellent companions. All of the plants have brought color to our green space and provided essential habitats for butterflies, birds, and many other animals and insects. Click on the thumbnails below for larger images.