Over the past several years, you could talk to any home gardener and they would increasingly be able to tell you firsthand how they’d had to adapt their gardening plans in response to fluctuating climate conditions — shifting planting times or mixing up what they’re growing. In late 2023, the Department of Agriculture seemed to validate their experiences when it released its updated plant hardiness zone map — moving more than half of the U.S. into warmer climate zones.
The well-regarded map distinguishes different growing regions in the U.S. based on 30-year averages of the lowest annual winter temperatures at specific locations. Knowing what zone they’re in helps gardeners and farmers determine which plants will survive in their specific location and when to plant them to ensure that they thrive.
At the time of the new map’s release, the first such update in over a decade, the USDA stated that the changes were “not necessarily reflective of global climate change because of the highly variable nature of the extreme minimum temperature of the year.” And there are other factors contributing to the zone reassignments, including improved mapping methods and data from more weather stations than previous maps had incorporated.
But regardless of the reasons for the map’s new zones, climate change is certainly contributing to warmer temperatures and many other issues facing home gardeners. Read on to learn more about these threats and how you can protect your homegrown crops in future growing seasons.
Earlier blooms and unpredictable growing seasons
As the climate continues to warm, many home gardeners have been sowing or transplanting their annual plants earlier in the spring as the last frost has seemed to creep earlier and earlier each year. And the first frosts in many areas have been coming later, which has allowed some gardeners to harvest their crops, such as tomatoes, later in the season.
Estimated first and last frost dates are published periodically for different regions based on data from the National Oceanic and Atmospheric Administration. Gardeners often use these dates (in conjunction with hardiness zones) to ensure they are planting the right crops at the right time based on their location. It is important to note, however, that these dates are based on historical averages and are not guarantees.
As many gardeners find themselves with a longer growing season and milder temperatures, they may also be able to sow plants previously not suitable for their former growing zone. Conversely, crops, as well as native plants, previously well-suited for certain zones may no longer be viable. With blooms and foliage arriving earlier on plants and fruit trees, it also means that these plants are more susceptible to a surprise frost or bad weather early in the season.
Rising temperatures and excessive heat
Wilted lettuce, herbs that bolt, sunburn spots on squash: Excessive heat has always presented a problem for gardeners, but rising temperatures also shorten the window in which heat-susceptible crops can grow comfortably. And even heat-loving crops, such as tomatoes, struggle when the temperatures get too high. Excessive heat may deplete the soil of nutrients and restrict nutrient uptake.
Often, you can find seeds for certain varieties that are more heat-tolerant than others. Cilantro, for example, notoriously prefers cooler temperatures and will bolt (flower and turn to seed too early) the moment it gets too hot — but it’s easy to find seeds for slow-bolt varieties.
A constant struggle with inconsistent water patterns
Along with heat, drought is another problem that poses particular challenges for home gardeners. When natural rainfall is reduced, gardeners must turn to alternative irrigation methods to ensure their plants are well watered and able to thrive.
With drought becoming more common across the country and water usage concerns mounting, many are turning to drought-resistant crops and seeds to safeguard their gardens. The most common varieties of spinach, for example, do not react well to water stress and prefer evenly moist soil. But some spinach varieties, such as America spinach, which is related to the popular heirloom Bloomsdale spinach, are more drought-tolerant. Similarly, Malabar spinach (which is not related to common spinach but is instead a succulent plant) is extremely drought-tolerant and heat-resistant, making it a great alternative to traditional spinach crops in places where water scarcity is a consideration.
Drought isn’t the only water issue home gardeners need to contend with, however. Heavy rains and intense storms have also been hallmarks of the climate crisis in recent years. As with commercial farms, these rains have the potential to wreak havoc on a home garden either through flooding, bruising of plant leaves and fruit or oversaturation of soil, which can lead to pests and diseases.
More weeding as invasive plants take over
Invasive plant species are spreading into home gardens as shifting climates allow more favorable conditions for them to grow. These species are not native to a region and often spread quickly once they are introduced.
Invasive plants hurt garden habitats by rapidly overpopulating the area, blocking sunlight, draining water and competing with garden plants and native species for resources. If left untreated, these plants can crowd out other plants, which will begin to die off.
Many experts have speculated that one of the most notorious (and itch-inducing) invasive species, poison ivy, is poised to benefit from a warming climate as well as higher levels of carbon dioxide in the air. Those familiar with the plant already know that it is becoming more aggressive in its growth and is forming leaves earlier in the season — making it more challenging to remove, as the leaves are more poisonous than the stems.
Unfortunately, many home gardeners believe that the only way to combat invasive species is to use potent pesticides. However, there are more natural ways to manage invasive plants, such as heavily mulching around your crops and planting more native species within your garden and landscaping. Native plants are most likely to survive an influx of invasive species and can help build up a strong ecosystem by providing a space for native pollinators and other insects. And don’t forget, many invasive plants are actually edible weeds that you can forage right in your own backyard.
Gardens are prone to more diseases
Many of the aforementioned climate change impacts — warmer temperatures, drought, heavy rains, gardeners planting varieties new to their regions — all contribute to the possibility of new and increased threats of disease.
Warmth and wetness create the perfect breeding ground for several fungal plant diseases. One of these diseases, early blight, primarily impacts tomato and potato plants; browning leaves are the first sign, and if left untreated, the blight can spread to the stem and other parts of the plant, eventually killing it.
On the other hand, some diseases, such as powdery mildew, thrive in dry, hot environments, which are also becoming more common due to climate change. While diseases such as early blight and powdery mildew are already well-known by gardeners, they are appearing more frequently, especially for those in northern climates who are experiencing warmer weather than in prior years.
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