Category: Climate-ready gardening

Don’t be a Horticultural Hot Mess: Climate-Smart Gardening Practices

While there are still doubters out there mostly thanks to politics, it is pretty clear that the climate is changing and humans are affecting the speed at which it is occurring. The number of record-breaking temperatures and the shift in the USDA hardiness zones show the current effects of this change that will affect almost all parts of our lives, including gardening. What may be less apparent to folks is shifting weather patterns and the increased incidences of extreme weather. Just ask farmers about the weather and they can tell you how extreme weather has gotten. The funny thing is that while many farmers may doubt the existence of anthropogenic (human-caused) climate change, research has show that they believe that weather has gotten worse and that they change their practices and livelihoods to cope with those changes. So as gardeners we can also adjust our practices to deal with the changes as well.

I live in Omaha, Nebraska and we definitely have seen this uptick in extreme weather events this year. From over a dozen tornado touchdowns during the afternoon of Arbor Day (some friends and I got to shelter in place at a warehouse box store for a few hours that day) in a system that had 145 tornadoes across the Midwest. May 2023 was the driest month on record with just 0.17” of rain, feeding the already severe drought in the area. On the other hand, May 2024 was the second wettest May and the eight wettest May on record with 11.14” of rain – the amount that we would normally expect to receive between January 1 and June1 in any given year.

Tornado outbreak of April 26–28, 2024 - Wikipedia
There were 145 tornadoes tracked between April 26 & 28, 2024.

As gardeners we should consider both the long-term implications climate change and the short-term weather extremes that it brings and what sort of mitigation strategies may be needed. And while the individual effect of practices to reduce or sequester greenhouse gas emissions might be minimal, if many people practice climate-smart gardening there could be a small impact – every little bit helps.

Mitigating practices for climate-smart gardening

At this point the change is already happening, so it is wise to think about what practices we need to adopt in the garden to deal with current weather pattern changes and the overall changes of the climate such as increased heat and changing precipitation (some places get less, some places get more). Here are some things to think about:

Plant climate-resilient plants

The advice I often see is that gardeners should “just plant natives,” but it isn’t really as simple as that. Yes, native plants are adapted to the current environment of the area, but will they necessarily be adaptable when that environment changes? The native range for many plants, namely cold intolerant ones, will expand as more areas warm. But some plants can’t take the heat. Changing weather patterns also means that areas may become drier or wetter which could affect what grows successfully in an area. To add to this double whammy, most gardeners are planting in urban areas that have been drastically altered from the local native habitat in terms of soil, temperature, water, and more which may make conditions less favorable for native plants. It isn’t guaranteed that what grows as native today will survive in tomorrow’s climate.

It is best to take a blended approach – incorporating native plants that are likely to do well in evolving climate conditions and adding introduced plants from areas similar to what the climate is changing toward. Also keep in mind that many plants, especially fruit trees, require a certain amount of cold weather, referred to as chill hours. These requirements make it difficult, if not impossible, to grow many cultivars of fruits like apples, pears, plums, and blueberries in southern Florida, Texas, and California. As temperatures rise, the areas that struggle to grow these fruits will expand. It is even difficult to grow crops like tomatoes in some of these areas because extreme heat sterilizes pollen and slows fruit maturation. Resilient gardeners may have to turn to climate resilient (heat tolerant) vegetable cultivars in the future.

Chilling Hours: between 35°F and 45°F, Oct. 1 start
Source: Midwestern Regional Climate Center

different fruit and nut tree species ...

Source: Climate change trends and impacts on California agriculture: a detailed review

Improve Soil Health

Healthy, organic-matter rich soil retains water better and supports plant nutrition. Supporting plant health makes them better able to grow when environmental conditions aren’t exactly perfect. Soil organic matter collects and holds water over long periods, making it available to plants longer term if conditions become dry. It can also aid in drainage if conditions become wetter. Increase organic matter through the application of mulches and composts. In vegetable gardens, cover crops can also be an effective means of adding organic matter and nutrients to the soil.

Water Management

Aside from building soil health to retain water, using mulch to reduce evaporation can also effectively improve water management. Organic mulches also help reduce and moderate soil temperatures, which is important especially during extreme heat periods.

Using effective and efficient irrigation can also help keep plants healthy while reducing water usage. Many perennial plants adapted to current environmental conditions (whether they are native or not) can survive without large amounts of water input during normal periods of precipitation. However, during extreme heat or drought even low-water plants may need supplemental water. Most all plants also need supplemental water for the first few weeks or months after planting until they are established.

Create Microclimates

It is a fairly common practice to create microclimates to protect tender plants in cold weather, such as planting near walls or using protective structures like low tunnels or high tunnels for vegetables and fruits. As temperatures rise gardeners may need to consider creating microclimates to protect plants from heat or extreme conditions like wind. The use of shade cloth or shady areas, trellises, and wind breaks can help protect from extreme temperatures, harsh winds, or excessive sun exposure.

File:烏來生態農場溫室草莓.jpg - Wikimedia Commons
Shade structures to reduce heat. Source: Wikimedia Commons

Planting Adaptations

Aside from changing what is planted, when things are planted might also need to change. Planting times for vegetables, fruits, and annuals will likely shift earlier, especially in areas with extreme heat that would negatively effect plants.

Promote Biodiversity

Planting a variety of plants, both native and introduced, will be helpful if the environment becomes unsuitable for certain species. That way, you haven’t put all of your eggs in one basket. Biodiversity will also support wildlife and insect populations that will also be effected by the changing climate. Having a variety of plants for food and shelter will be paramount for supporting pollinators, songbirds, and other species.

Can you effect climate change from your garden?

Like I said earlier, individual garden practices would likely have little effect on slowing climate change, but if lots of gardeners change practices there could be an effect, even if it is somewhat minimal. Every little bit helps. I left extension back in October to work for a company that supports farmers in conservation and climate-smart practices that add carbon to the soil and therefore reduce greenhouse gas emissions. The effect of an individual farmer would be minimal, but working with hundreds or thousands of farmers and hundreds of thousands of acres of crops can have at least some impact.

So what can you do as a gardener? The thing that most people think about is reduced usage of power equipment that relies on gas or diesel. While electric and battery tools rely on the electric grid that still uses fossil fuels, as the grid continues to add renewable and sustainable energy sources the carbon footprint will continue to shrink.

But one of the best things gardeners can do goes back to soil health. Organic matter build up in the soil sequesters carbon. Therefore practices that add organic matter to the soil can also have an impact on greenhouse gas in the atmosphere. Adding organic matter is a starting point, but you want to make sure it stays there. In annual production systems like in vegetable gardens, tillage promotes the decomposition of organic matter which releases the carbon back into the atmosphere. Minimizing soil disturbance by adopting no-till practices is a key step gardeners can take to reduce their carbon footprint (and positively effect soil health). Eliminating soil disturbance when establishing new perennial beds is also beneficial, but perennial plantings, especially trees, are great at sequestering carbon deep in to the soil for the long-term.

Sources

Don’t get hosed: exploring the efficiencies of garden and landscape irrigation systems

As many parts of the US face drought or dryer than normal conditions and issues about water availability especially in the western states, many gardeners are reassessing their relationships with plants and irrigation.  Many gardeners, especially in the west, are replacing their lawns and landscape plants with more drought and dry-weather tolerant options.  But there still are times when irrigation might still be necessary, e.g., growing vegetables and fruits, establishing new plants, and more.  Using water efficiently and effectively is key in these situations even when water is available and drought conditions aren’t as prevalent. Efficient water use and good irrigation can also mean a savings on the water bill AND a reduction in plant diseases spread by water application on the leaves. Paired with mulching, efficient irrigation can drastically reduce the amount of water used in gardens and landscapes.

 In order to make the best choices for your garden, I’m going to talk through some of the most and least efficient irrigation methods for your gardens and landscapes. I’ll be starting with the most efficient methods and working my way to the least. 

Drip Irrigation

Drip irrigation is considered one of the most efficient methods of irrigation because it applies water directly to the soil at the base of the plant and therefore typically uses the smallest volume of water. Research shows that drip irrigations have around a 90% efficiency rate. . Most systems sit above the ground and apply water to the soil surface, but some sub-soil systems are available. The system usually involves a filter and pressure regulator to keep the emitters functioning and applying water at the proper volume.

This drip tubing has pre-installed emitters along the tube and drips small volumes of water directly on the soil near the plant.

The efficiency of drip irrigation comes with a caveat though. When applied to sandy or rocky soils, water from drip irrigation has a much smaller spread laterally in the soil due to less capillary action and higher gravitational pull due to the large pore spaces. This means that there isn’t as much coverage of water in the root zone. In order to combat this drip emitters must be closer together or have a high flow rate, both of which increase water usage and reduce the effectiveness of drip irrigation in sandy soils. Read more here

Source: Soil Type Influences Irrigation Strategy, MSU Extension, Ron Goldy

There are typically two types of application methods: tubes or tape that have pre-made emitter holes at set distances that disperse a set amount of water per hour or emitters that are inserted into the end of solid tubes (that may or may not have an adjustable flow rate).  The tubes and tapes that have holes pre-made are typically used in vegetable gardens, row crops, or in beds where plants are uniformly planted.  Systems with the inserted emitters are often used in landscape settings where it makes sense to water individual plants, such as trees, shrubs, or large perennials. 

Given the low volume of water disbursed by the system, water pressure is regulated in a way that ensures even distribution as long as it isn’t modified than from the manufacturer or factory specs.

For information on installation and maintenance, check out these resources:

Drip Irrigation for Home Gardens – Colorado State Univ. Extension

Irrigation Video Series – Oklahoma State Extension

Microsprinklers

Microsprinklers function on the same type of system as drip irrigation and can sometimes even be combined with drip systems.  Instead of small openings that drip water on a small area on the soil, microsprinklers spray a small volume of water over a set radius.  The sprinkler heads are typically only a few inches above the soil and therefore apply the water at the base of the plants. Some systems allow you to switch out sprinkler heads that spray in different patterns and distances.  One such system that I’ve used has sprinkler heads for patterns from 90 to 360 degrees and from one foot to ten feet in diameter. 

This microsprinkler has an adjustable head to apply water in a 1 to 5 foot diameter.

While not as efficient as drip, microsprinklers are more efficient than other systems due to low water volume and consistent pressure throughout the system.  They can be more flexible than drip irrigation in settings like landscape beds and around trees and shrubs since one emitter can water a larger area with less tubing and fewer parts. 

Soaker hoses

Soaker hoses are popular because they are plug-and-play.  You can just attach them to your faucet and don’t have to worry about cutting and assembling tubing and parts. Water is released through the surface of the entire hose, making water application much less precise that drip and microsprinklers as well. Keep in mind that soaker hoses don’t have pressure regulation like drip and microsprinkler systems do so you’ll often find inconsistent watering when you use them.  More water leaves the soaker hose at the end closest to the faucet and less (or none) at the far end.  The result is usually excess water in some parts of the garden and not enough in others. 

Soaker hoses also release a much higher volume of water than drip and microsprinkler systems, which can result in overwatering and water waste. I learned this from experience when I accidentally left a soaker hose running for about three days.  The garden was nicely flooded and the water and sewer bill topped out at over $500 that month. 

Sprinklers

Sprinklers are probably the most common irrigation system used because of their simplicity.  Home gardeners might use the hose-end individual sprinklers purchased at the garden shop which can quickly water a large area.  And many homeowners, especially in areas where there isn’t rainfall sufficient to support grass growth, have sprinkler systems installed in their lawns.  However, sprinkler systems are only around 65-75% efficient. Spraying water in to the air, especially on hot and dry days, reduces efficiency through evaporative loss.  Sprinklers are also less precise in where you can aim and apply water. There’s also the added issue that overhead application of water can lead to or worsen plant disease issues by making conditions favorable for the spread and growth of fungi and bacteria. If possible, use sprinklers only on a temporary basis like establishing new plants or make sure they are calibrated effectively.

Hand watering

While hand watering probably uses a smaller volume of water than sprinklers and you can direct water more precisely, there are still issues with evaporation and overhead watering.  In addition, hand watering is usually less effective than other methods because humans are impatient and actually don’t water long enough.  Most plants will benefit from a long, deep watering but many gardeners will only give a pass or two with a water hose and will underwater plants.  This can cause roots to accumulate in the upper layer of the soil and increase long-term water needs of the plant.  Rely on hand watering for temporary needs like plant establishment or container plants (though you can use drip and microsprinklers in containers as well) and use a more efficient strategy long term. 

I recently worked with a local community garden to install several thousand square feet of drip irrigation. The system will save them many hours of hand watering labor each week.

Wrapping it up

There are a number of ways you can manage the water needs of your landscape, from renovating your landscape with more water efficient plants to making more efficient use of water through effective and efficient irrigation systems. As more and more cities and states across the US place restrictions on water use having several irrigation tools in your toolbox will be helpful.  Always remember that the best strategy is to grow plants suited to your environment to reduce water use in the garden. And in places where there isn’t sufficient water for grass to consider removing lawn and replacing with native vegetation and xeriscaping.  Irrigation systems can help in areas with unexpected drought or weather issues but for long-term sustainability gardeners in drier climates should adapt their properties where they live.

Other Sources

Drip Irrigation