Gardening in a Changing Climate
Many states have shifted at least 1 full zone on the Plant Hardiness Scale.Posted Apr 16, 2015
It’s become commonplace to turn on the news and hear about remarkable weather events. Just last month, weather reports showed record-breaking warm temperatures in the Pacific Northwest, record-breaking temperatures well into the 90’s in Los Angeles, and yet another foot of snow in New England, further breaking all-time snow accumulation records in the region. February temperatures were 20- 40F below normal from the Mid-Atlantic to the South. These weather reports make for interesting conversation and it may seem like change is happening only on a broader perspective, but if you have a home garden you are most likely seeing the signs of a changing climate right in your own backyard.
Early blossoms and unseasonal frosts are just two small signals among many that have gardeners scratching their heads. It seems the only thing to do is embrace the chaos and adapt for the new times ahead. Here’s a look at some of the upcoming conditions gardeners may face and what to do about them.
Gardeners Know Timing is Everything
Many gardeners are finding the timing of everything seems to be shifting. Plants are blooming earlier and frost date patterns are irregular. Plant researcher Zoe Panchen asserts that in some locations, plants are blooming up to 1½ days earlier per decade compared to 150 years ago. This may mean some bees arrive too late and miss the necessary cycle of pollination that affects your flowers and vegetables.
Frost dates are shifting, so gardeners may be planting at different times than they were several years ago and some plants that have historically done well in the garden may cease to thrive in present conditions. Unexpected early and late frost events can hinder growth and damage young plants. According to David Inouye, professor of biology at Maryland University, “Frost determines the growth range for many species of garden and agricultural plants, so changes in the distribution of frost in the future may influence where certain plants can be grown.”
Measuring soil temperatures with an inexpensive soil-testing thermometer is a way to get an accurate read on what is going on under the surface of the soil. This will help you determine the ideal planting time for your garden crops. Calculating the new average frost dates is made easier if you check with the National Oceanic & Atmospheric Administration (NOAA), frost/freeze date probabilities chart updated in 2012.
Plant Hardiness Zone Changes
According to a recent press release from the National Arbor Day Foundation, many states have shifted at least 1 full zone on the Plant Hardiness Scale when compared to years past. The unpredictability of the weather also makes it hard to determine whether it will be wetter or dryer in your location in a particular year. So when planning your garden, it may be wise to choose varieties that do well in both arid and wetter climates.
Consider planting for the climate that you are already familiar with, as well as what the climate might do in the future. This is especially important if you are intending to plant a long-lived species, such as a tree. A tree that is doing well today might be struggling in 20 or 30 years. Try www.planthardiness.ars.usda.gov for a more in-depth look at planting parameters for your region.
When There’s Not Enough Water
The recent water restrictions in California and the alarming projections for water availability in the US western states, are wake-up calls to gardeners across the continent: water availability is changing.
In general, the changing climate is resulting in shorter spring seasons, while summer and fall are lengthening. This can result in drought-like conditions which can cause the soil to harden into a crust, making it not only hard for water to be able to permeate but also making it more difficult for the soil to hold any water that it is able to absorb.
To offset drought conditions, consider adding organic compost to enhance the condition of the soil by binding particles together which hold water and nutrients in place rather than letting the water pass through too quickly. This also gives the roots of the plant something to anchor to.
Mulching is another way to protect the plants from drying out quickly by holding in moisture. Mulch also moderates soil temperature fluctuations, which helps prevent plant stress. Mulch also protects the root systems of plants that may be otherwise pushed out of the ground by the natural expansions and contractions that occur in the soil as it cools off and heats up. Mulch also helps to keep roots cooler during high heat periods.
When There’s Too Much Water
Unpredictable downpours can damage delicate crops, flood out seed beds and erode your valuable garden soil and amendments. Some precautions can help reduce the impact of too much rain.
Trenching can be a helpful way of providing a place for the water to go in flash heavy rains. Shallow trenches can be dug between rows of plantings in garden beds, or conversely, plantings can be set in mounded soil. These shallow trenches can serve a second purpose as ‘compost trenches’, where unfinished compost can be set to finish off and be readily available to plant roots.
Deeper trenches can be dug in strategic locations around and through your garden to direct excess water to a safe area for overflows. The contours of your garden will dictate the course for trenching, and a depth of 12” or more is recommended. Any trench in your garden, however, can also be a hazard. Be sure to dig trenches wide enough that they are easy to see to anyone strolling through your garden, and if the trenches are narrow then they should be covered with boards which are robust enough to be stepped on without collapsing into the trench.
In case of a sudden downpour, it might be a good idea to have a portable cloche on hand. This small cloche is light enough for a person to lift and move to cover seed beds and vulnerable crops. When that unexpected hailstorm comes in May, set the cloche over your salad greens bed or starter trays to shield them.
Greenhouse – Shelter in Any Season
The best protection for a garden in a changing climate is a greenhouse. Long favored by nurseries to propagate seedlings in late winter months for the spring garden season, greenhouses are now popping up in backyard gardens across the country. Modern greenhouses use high-tech unbreakable plastics instead of the old glass models, and the cost has gone down while many new models have become available to consumers.
A small backyard ‘starter’ greenhouse can provide protection for seedlings and enable the gardener to start crops early. This is especially valuable as shorter spring seasons are one of the results of climate change. Once the seedlings are set out, some full season crops which do best when foliage remains dry, such as tomatoes, can be grown in the greenhouse all summer.
A ‘grower’ greenhouse is larger than the ‘starter’, and provides space and conditions for full-season crops, and in many regions of the country gardeners can produce crops year-round in their backyard greenhouse.
To learn more about the different types of greenhouses and what would work best in your garden, see our Guide: Greenhouses: How to Choose and Where to Buy
Learning to Pay Attention
For a holistic approach to coping with the changes in your garden, try applying the principles of permaculture. Permaculture teaches you to get a feel for your environment and to work with, rather than against nature, by concentrating your awareness on the existing patterns and interactions in your garden’s environment. For more information on permaculture, stay tuned for the upcoming article titled Go With the Flow- Using the Principles of Permaculture to Enhance your Garden.
Change is the only constant in life. Adaptation is essential if we are to continue growing. From zone 2 to zone 10, from snow on roses to scorching Octobers, embrace the chaos and find your garden’s new rhythm along the wild ride of climate change.