Gardening During the Age of Climate Change

Gardening During the Age of Climate Change

The Texas Panhandle is known for its rapidly changing weather, where temperatures race up and down a thermometer on a somewhat regular basis. Now, global warming is bringing the additional challenge of not only changing weather, but a changing climate. Springtime months are warmer forcing plants from dormancy earlier. Blooms can appear two to three weeks early, causing complications in the plant/insect interactions. And once bloomed, springtime gardeners are in weekly fear of a sudden freeze that ends the blooming and leafing out process until the plant recoups. Increased stress for plants and gardeners alike. (Late frost damage this may nips early buds on columbine, photo at right.)

Once up and growing, hail, wind and long-term drought damage plants. Sudden and fierce rainstorms pound weakened plants whose root systems fail to hold the soil in place. Additionally, a warming planet doesn’t preclude early devastating autumnal freezes. Yes, we in the Texas Panhandle have struggled with these conditions in the past. They are not going away, and most likely will get worse. 

Gardening is not for the faint of heart.

Some may yet dispute the causes of global warming and climate change. Globally, nationally and down to the state and city level, government, scientific and affiliated associations all agree that global warming and climate change is happening, and that it is, at least in part, human caused. Even the faculty of the Department of Atmospheric Sciences at Texas A & M, that notable Texas conservative university, agrees and predicts temperatures to rise an additional 2.5° - 7°F (having already risen nearly 1.5° F.) by the end of this century. We, today, face many challenges because of climate change, but it pales into comparison what our grandchildren and great grandchildren will face to survive.

The state of Texas leads the nation in extreme weather events. Between 1980-2017, the state of Texas has experienced 48 billion plus dollars worth of storm disasters, and over 14 billion dollars worth of drought events during the same period. The cost of increasingly severe tornadoes, floods, hurricanes, high winds, hail, wild fires, and drought applies to gardens as well as agriculture, infrastructure, business, industry and homes. (“Climate disaster maps shows Texas is clearly the most apocalyptic state in the nation,” Chron, June 15, 2017.) The cost of these weather extremes effects every person on Planet Earth in increased insurance premiums, increased taxes, increased transportation costs, and increased costs of goods, especially food.

The American Public Gardens Association has added a Garden to Garden Disaster Response Center and lists over 25 botanical gardens, zoos and nature centers that were damaged, severely damaged and or closed due to the 2017 hurricane season, mainly located in Texas, Floria and the Caribbean Islands. Botanic collections, buildings and infrastructure met with damage or destruction. Also listed on the American Horticultural Society’s website are other gardens damaged by hurricanes in Georgia, the U. S. Virgin Islands. Quarry Hill Botanical Gardens, Santa Barbara Botanic Gardens, and the Ventura Botanical Gardens in California sustained damage by wildfires in 2017. (Photo at right of hail damage to geraniums in pots, May, 2013.)

Botanical Gardens, zoos and nature preserves close to the coasts are starting to do studies to determine how best to preserve their plant and animal collections in the face of rising seas. Montgomery Botanical Center in Coral Gables, FL, released a study in January, 2018 to determine their plant collection’s “half-life.” In their study, they readily admit their gardens and plant collections have been negatively affected by bad weather; now they are studying what the impact of “bad climate” will have, and how much land they will lose to rising ocean waters in the next 100 years. The study determined they would loose roughly a third of their land due to sea rise. But surprisingly, “the Montgomery Botanical Center collection will retain no more than 0.8% of its current plants 100 years later, even if the total inventory number continues to increase (Figure 5). Thus, an estimated 120 plants present in 2017 will survive until 2117.” This is chilling indeed.

What is our climate changing to? We haven’t yet arrived at the final outcome of global warming. With levels of CO2 increasing in the atmosphere and the global temperature rising, global climates are in a transition period, a state of flux. It is uncertain how much will be done to curtail CO2 emissions. We don’t know for certain what our climate will end up being. We need to be prepared to mitigate some of the issues and adapt to others to avoid human suffering that will be experienced by the grandchildren and great grandchildren of people alive today.

What is a Gardener To Do?

Gardening during an age of climate change is a subject of research both in the United States and abroad. Dr. David W. Wolfe, Cornell University, a professor of Plant and Soil Ecology in the Department of Horticulture, and a collaborating scientist with the U.S. Climate Change Program, researches, writes and teaches on the subject. The Royal Horticultural Society released it’s Gardening in a Changing Climate Report in 2017, and the New York Botanical Gardens, also a global leader in horticultural research, came out with What Gardeners Can Do, as did the Union of Concerned Scientists, to name a few.

Climate change’s effects on gardening and agriculture for the United States were summarized in the Third National Climate Assessment released in January, 2013 (the Fourth National Climate Assessment is due to be released towards the end of 2018). These effects include more than just untimely freeze-back of springtime garden ornamentals. The effects are huge and will a broadly impact our planet:

1. Reduction on ecosystems to reduce their ability to improve water quality and regulate water flows.

2. Climate change, combined with other stressors, is overwhelming the capacity of ecosystems to buffer the impacts from extreme events like fires, floods, and storms.

3. Landscapes and seascapes are changing rapidly, and species, including many iconic species, may disappear from regions where they have been prevalent or become extinct, altering some regions so much that their mix of plant and animal life will become almost unrecognizable.

4. Timing of critical biological events, such as spring bud burst, emergence from overwintering, and the start of migrations, has shifted, leading to important impacts on species and habitats.

5. Whole system management is often more effective than focusing on one species at a time,and can help reduce the harm to wildlife, natural assets, and human well-being that climate disruption might cause. (Climate Change Impacts in the United States, Chapter 8, Ecosystems, Biodiversity and Ecosystem Services.)

Royal Horticultural Society's Implications for Gardeners

In advising gardeners about climate change, the Royal Horticultural Society summarizes the “Implications for Gardeners.” Although the RHS has written this, in particular, for Great Britain, much of what they have found applies for us as well. It’s a global condition.

1. Warmer springs and autumns will extend the growing season, with some species flowering earlier and some autumnal delayed leaf coloring and leaf fall. This implies a need for more watering, weeding, mowing and pruning.

2. A longer growing season might allow for a wider variety of plant species to be grown. Gardeners will face a continual trace-off between a longer growing season and extreme weather events.

3. The amount of solar radiation available for plant growth has increased by around 5% compared to 1961-1990, linked to a reduction in cloud cover.

4. Extreme rainfall events might increase the rate that nutrients, particularly nitrogen, are washed out of the soil. Therefore, the timing of fertilizer applications should be carefully considered.

5. Dry spells are projected to occur more often, therefore gardeners will need to consider methods of capturing water during intense rainfall.

6. It is expected that warmer conditions will favor the spread of existing pests and diseases, in addition to aiding the establishment of new cases. However, climate change will mean that populations of those pests and diseases who exploit frost wounds, for example, may struggle to survive.

7. Even if greenhouse gas emissions are reduced today, the climate will continue to change rapidly over the coming decades due to historic emissions. Consequently, gardeners should be mindful that trees planted now might not be suited to the climate in 2050, for example.

(Gardening in a Changing Climate, Royal Horticultural Society.)

It is often pointed out that increased levels of CO2 in the atmosphere provides a positive benefit – that plants, including the grain crops that provide a large share of the world’s food supply, will grow faster and provide greater food yields. Research is finding that it wouldn’t lead to better nutrition. “Research published in the journal Nature, found that wheat, rice and soybeans grown in high carbon dioxide conditions have lower levels of these important nutrients {zinc and iron}. The finding has major global health implications, as nearly 2 billion people around the world receive 70 percent or more of their dietary zinc and iron from these types of crops.” (Inside Science, Elevated Carbon Dioxide Levels Robs Crops of Nutrients, May 7, 2014.) (Photo of blackfoot daisy and calylophus, two Texas Panhandle native plants that make great garden plants at upper right.)

“Previous research has found evidence that elevated carbon dioxide levels can lead to lower agricultural yields and reduce the protein content of food crops, Frumkin added, and the finding now that zinc and iron are also affected raises the possibility that a host of other "micronutrients" such as iodine, selenium, and individual amino acids could also be impacted. "It's a new area of research opening up now," he said.” (Inside Science, Elevated Carbon Dioxide Levels Robs Crops of Nutrients, May 7, 2014.)

Additionally, Dr. David Wolfe, a leading authority on the effects of climate change and rising CO2 levels on plants, soils and ecosystems noted: “Our results indicate that many crops will have yield losses associated with increased frequency of high temperature stress, inadequate winter chill period for optimum fruiting in spring, increased pressure from marginally over-wintering and/or invasive weeds, insects, or disease, or other factors. Weeds are likely to benefit more than cash crops from increasing atmospheric carbon dioxide.” (Mitigation and Adaption Strategies for Global Change, “Projected change in climate thresholds in the Northeastern U.S.: implications for crops, pests, livestock, and farmers”, Dr. David W. Wolfe, Cornell University; etal, June, 2008.)

Adapt your Garden to Climate Change -- Advice to Gardeners From a Climate Change Expert

Recommendations made to gardeners by the above mentioned individuals and institutions informs the gardener on how best to adapt to today’s changing climate. These recommendations won’t prevent difficulties in one’s garden, but will help our plants survive and thrive as best they can in surmounting the challenges a changing climate presents.

Dr. David Wolfe is one of the authorities on the effects of climate change on plants and frequently speaks on this topic to esteemed academic and professional organizations, as well as to Master Gardening associations near Cornell University in New York. Dr. Wolfe has written Advice to Gardeners from a Climate Change Expert to aid gardeners in surmounting the challenges climate change presents. I’ve copied his advice and elucidated as applicable to our climate in the Texas Panhandle.

Experiment with new species

Dr. Wolfe advises: “If your favorite plants become less able to thrive in new climate conditions, experiment with new species and varieties as plant hardiness zones shift. Dr. Wolfe urges cautious experimentation rather than many radical changes in a single year.”

Our Texas Panhandle climate is predicted to be hotter and drier in the years to come. As we have seen just this past decade, we’ve experienced record breaking dry years, and years with above average precipitation, with occasional flooding events in some areas. Hail, high wind, and temperature fluctuations damage and kill our garden plants on an irregular basis.

We may have to reach for not just the prettiest plant on the nursery bench, but the most versatile. Native plants have proven their adaptability over the centuries. Give some of the drought tolerant plants a try, those native to higher elevations of the American Southwest. Many of them are cold hardy, heat tolerant, lower maintenance and water thrifty – and look good too. Plants Lists on this website describes many of the adaptable plants suitable for our area.

Move up planting and harvesting dates

“Projected longer periods of high heat accompanied by low precipitation may require gardeners to shift to slower-growing, drought tolerant plant varieties. Take advantage of an earlier spring and a longer growing season by setting an earlier planting date. This can reduce plants’ exposure to high heat later in the summer.”

Spring planting is a little risky in early spring, what with all the temperature shifts. And the temperature differences in rapid temperature drops are likely to increase, increasing stress on plants. Consider fall planting. Planting in the fall allows the plant to develop a strong root system during the cooler autumn-winter-spring months before our most stressful season begins in June.

Manage water

“Rain is predicted to fall in more intense events, which can cause plants to have “wet feet” and root disease. Identify where water pools in low spots and reconfigure for better drainage. Use soil amendments to improve drainage during wet periods or to improve water-holding capacity during dry periods.”

Our gardens and plants could be impacted by too much water too fast and for too long in poor draining soils. But for most home gardeners, this will not be the case. The Texas Panhandle is most impacted by prolonged periods of drought, as we were for the last six months (scant rain in Amarillo from October 15, 2017 to April 20, 2018). One great drawback many gardeners experience is compacted soils that don’t allow adequate in-soak of rain that does fall. Amending your soil for better absorption of moisture will prevent needless runoff. Review the article in HighPlainsGardening.com on Understanding and Amending Our Soils.

Protect plants against frost

“If higher temperatures come earlier than usual, trees and shrubs may leaf out earlier, making them vulnerable to spring frost. Use freeze-protection mulch or reusable fabrics to cover these plants in the case of frost. Avoid planting on north-facing slopes and low-lying shaded areas that are more subject to frosts.”

If one elects to plant early in the spring, the use of frost blankets on vegetables and ornamental annuals is extremely helpful. I favor fall and winter vegetable gardening using the two tunnel system described in the February Stepping Stones. In the face of sharp temperature drops, I keep medium and heavy weight frost cloths on hand for covering ornamentals, vegetables and spring bulbs that are trending to quite early blooming. In my raised vegetable beds, I also use a 6 mil poly cover over the frost cloth during the months of December into February. I am finding that I can remove the poly tunnel layer much earlier in winter than in the first decade of this century because of overall winter warming. (Freeze and frost protection supplies photo at right.)

Be aware of any new invasive threats

“Higher temperatures are predicted to bring increased weed, insect, and disease pressure. Keep up with the latest information provided by local Cooperative Extension experts on any new pest threats.”

We will not be immune to this occurrence either. Defensive gardening is the strongest offense against the threat of insect and disease. Climate change puts greater stress on plants. By insuring the plants nutrient and water needs are adequately met, their immune system will put up a better fight. Review the principles involved in Creating an Organic Landscape for tips on helping your plants cope with climate change.

Adapt your garden for Native Pollinators

More advice from Dr. Wolfe on the all important subject of our native pollinators: “Insects are essential to the reproduction of most flowering plants, so supporting a variety of pollinating insects throughout the growing season is beneficial for the success of your garden and surrounding natural landscapes.”

“Climate change impact may cause some plants to shift when they produce flowers, and other plants to grow poorly. To ensure that your garden provides nectar throughout the pollinator season, follow these tips:”

Support pollinators throughout the growing season

“Choose a planting palette that blooms throughout the growing seasons, from spring to summer to fall.”

Much as been written about planting for pollinators. If we wish to continue to enjoy the service these pollinators provide, we must help them. My GardenNotes on Attracting Pollinators With Annual Plantings and creating Pollinator Friendly Gardens are two sources to refer. (Photo of native gayfeather with butterfly at right.)

Provide “depth in the bench” in your garden

“Choose multiple species of plants that perform the same roles at once. By planting multiple species of flowering plants that bloom at the same time, if one plant species in your garden succumbs to environmental impacts or disease, others will still be present to provide nectar and pollen for pollinators in that same flowering window. This is called “functional redundancy.”

It is difficult for most home gardeners to practice this recommendation. Our home lots are small and the space allowed for ornamental plants is tiny, compared to the percentage that is taken up by lawns. Implementing this recommendation involves a commitment on the part of the homeowner-gardener. The question remains across the gardens of America, “just how committed are we to helping our pollinators survive?”

Keep your garden flexible

“While there are projections for climate change in the future, there are many unknowns. One way to be prepared is to include a mix of flowering plants that have a diverse range of responses to environmental conditions. For example, if the summer is especially warm, only some of your plants may experience stress, while the heat tolerant ones can thrive in the warmer conditions. This is called “response diversity."

Again, this will take a commitment on the part of the homeowner-gardener.

Shrink Your Garden’s Carbon Footprint

Dr. Wolfe continues his advice on how gardeners can help reduce atmospheric carbon input. “Try these suggestions to move your garden closer to a carbon-neutral state:”

Reduce or replace nitrogen fertilizer

“Synthetic nitrogen fertilizers such as urea and ammonium nitrate require a lot of energy to manufacture and transport (for every ton of fertilizer produced, 4 – 6 tons of CO2 is emitted).”

“As a replacement

  • Set your mower higher than three inches to promote root growth and exploration for more soil for nitrogen

  • Leave lawn clippings in place on the lawn, since they hold nitrogen and other nutrients, which are recycled back to the lawn.

  • Use organic nitrogen sources, such as manure and compost.

  • As in gardens, avoid applying nitrogen in very early spring.

  • For healthy, mature lawns in shaded areas, try using only two applications of supplemental nitrogen per 1,000 square feet.

  • If you must use synthetic fertilizer, choose urea over ammonium sulfate or ammonium nitrate, as the production of urea produces less greenhouse gas emissions.”

Or one could plant buffalograss, our native turf grass. Dr. Wolfe lives and gardens in New York state, where growing buffalograss is not an option. It is an option for the Texas Panhandle. With a turf of buffalograss, mowing, watering and soil amending are greatly reduced. With the new varieties available, the aesthetic benefits have improved too.

Dr. Wolfe also advised to avoid using nitrogen fertilizers in very early spring. If the soil isn’t warmed sufficiently, plants will not be growing and taking up nitrogen. Nitrogen is water soluble and will run off, polluting out streams, lakes, rivers and Gulf of Mexico. Also, nitrogen fertilizer gives off nitrous oxide, a potent greenhouse gas, as it degrades in the soil.

Rethink lawns

“Cut down the need for gas-powered mowers and fossil-fuel based fertilizers by replacing high maintenance turf with no-mow grass varieties.”

A turf with buffalograss and bluegrama grass or other low maintenance/low water turf blends, one can implement this suggestion. High Country Gardens and Native American Seeds have several options depending on your locale.

Make Your Garden a Carbon Sink

“Till your garden less, and instead let plants decompose and become part of the soil's organic matter naturally. This prevents carbon from being released into the atmosphere, but instead kept in the soil, an important component of soil health.”

Soil Carbon Farming

Gardening and agriculture both need a paradigm shift if we are to be successful in the age of climate change. The current gardening and agricultural models aren’t helping to reduce atmospheric carbon. Our focus needs to be in carbon capture and use. The most important greenhouse gases directly emitted by humans include carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and several others, (Causes of Climate Change, EPA.) Erosion and degradation of soil caused by the modern farming techniques of plowing, intensive grazing and clear-cutting “has played a significant role in the atmospheric accumulation of heat-trapping gases. ...The world is warming not only because of fossil fuels are being burned, but also because soils, forests and wetlands are being ravaged.” (“Can Dirt Save the Earth?”, Moises Velasquez-Manoff, New York Times, April 18, 2018.)

The idea of carbon farming -- putting some of the carbon back into the soil and into grasslands and forests, and then slowing the release of carbon dioxide – is gaining ground. The goal is for the amount of carbon leaving a given ecosystem to be less than the carbon entering it. Soil scientists here and abroad are researching and publishing papers that show that better “land management practices are one of the few affordable options available today for drawing down carbon.” Some of these new land management practices “include agroforestry (growing trees and crops together increases carbon retention), no-till agriculture (plowing causes erosion and carbon loss) and keeping farmland covered (bare dirt bleeds carbon).” (“Can Dirt Save the Earth?”)

Increasing the carbon in soil not only reduces the amount of carbon dioxide in the air, but improves soil organic content, water absorption and retention, and plant health. It also reduces the amount of energy intensive chemical fertilizers, which decreases the amount of nitrous oxide, a byproduct of excess nitrogen use and powerful greenhouse gas. (“Can Dirt Save the Earth?”)

In the home garden, we can farm our own carbon by pulling weeds and letting them decompose in place, use a mulch-mower to directly and immediately recycle grass clippings, collect and shred leaves in the fall and spread on beds, borders and turf, and recycling our own other plant debris by home composting.

Plant Strategically

Dr. Wolfe continues his advice on gardening sustainable in a changing climate:

  • “Choose native plants, which are adapted to local climate, soil, pests and diseases and require less protection, water and fertilizer. Try your best to place plants in a location that provides the right amount of light, moisture and drainage needed for the plant to thrive without unnecessary inputs.

  • Look for the "Veriflora Certified Sustainable Grown" label on plants, which means it meets standards for environmental and social responsibility

  • Avoid buying potting mixes, as most contain synthetic fertilizer. Instead make your own by mixing 1/3 compost, 1/3 garden topsoil and 1/3 builder's sand.

  • Planting more trees on your property can help take up CO2 from the atmosphere and place them to block winter winds and create summer shade to reduce the amount of energy required to heat and cool your home.”

HighPlainsGardening.com includes plants lists in several plant categories to aid Texas Panhandle gardeners in making more informed plant choices. Click here for the list of Trees, and other Plant Lists. Growing trees in our home landscape creates a lot of shade (which is good). If you have limited space, and want to plant for pollinators, plant fewer trees and more shrubs. The Texas High Plains’s climate is a challenge to tree growing, in the best of times.

Vary Your Vegetables

“Adding diversity of your vegetables by interplanting perennial vegetables and herbs with annual crops requires less fertilizer and maintenance than monoculture beds of annual plants.”

Texas A & M’s Aggie Horticulture provides a list of vegetable varieties suitable for the Panhandle and High Plains region. Mix up your vegetable beds with plants that will draw in pollinators and beneficial insects that will help keep down some insect pests.

Power Down and Recycle

Dr. Wolfe concludes with: “As an alternative to leaf blowers and weed whackers, mulch well to keep weeds down and rake a little every so often, which composts leaves in small bursts rather than in one big cleanup.

Reuse existing and salvaged materials for garden construction, like bricks and stone, to eliminate the need for manufacturing and transporting new products. Use recycled products whenever you need planter boxes, compost bins, garden hoses, fencing and pots.”
 

HighPlainsGardening.com

As a gardener who practices a more holistic form of gardening, the last point of the Third National Climate Assessment summary (quoted above) speaks volumes, that whole system management is often more effective than focusing on just one plant or one event. Highplainsgardening.com has endeavored to help the home gardener put into practice techniques, procedures and methods that naturally lead to success. I’m always on the look out for native plants that make great garden plants. The seven basic principles of gardening and the six principles of organic gardening are even more important during a period of fluctuating circumstances. By following the practices outlined in Creating Organic Landscapes, we will be able to adapt, at least in the short term, to this changing climate, while capturing carbon, instead of adding to the problem.

Today is Earth Day, a day when we focus our attention on how to be better stewards of our planet Earth. We should make every day Earth Day, by actively working to improve the environment, for ourselves, the plants and animals that presently inhabit this space, and for future generations. The future generations are our children, grandchildren and great grandchildren. Let us pass to them a planet where they are able to enjoy the natural delights we still have.

Resources

Advice to Gardeners from a Climate Change Expert, Dr. David Wolfe, Cornell University.

“Can Dirt Save the Earth?”, Moises Velasquez-Manoff, New York Times, April 18, 2018.

Climate Change Impacts in the United States, Chapter 8, Ecosystems, Biodiversity and Ecosystem Services, January, 2013.

Gardening in a Changing Climate, New York Botanical Gardens

Gardening in a Changing Climate, Royal Horticultural Society.)

Gardening With a Mission, Dr. David W. Wolfe, John MacLeod Annual Lecture at the RHS

Inside Science, Elevated Carbon Dioxide Levels Robs Crops of Nutrients, May 7, 2014.

Increasing CO2 threatens human nutrition, Nature, June, 2014.

The Climate Friendly Gardener, A Guide to Combating Global Warming from the Ground Up, FactSheet 2754, Union of Concerned Scientists, Citizens and Scientest for Environmental Solutions.

Mitigation and Adaption Strategies for Global Change, “Projected change in climate thresholds in the Northeastern U.S.: implications for crops, pests, livestock, and farmers”, Dr. David W. Wolfe, Cornell University; etal, June, 2008)

Regenerative Farming, Eric Toensmeier, November, 2013, YouTube video.

Angie Hanna, April 22, 2018 Earth Day