As climate change occurs, our gardening practices must adapt. By the end of this century scientists predict that hardiness zones may become one to two zones warmer in any given area.
With warmer temperatures, winters may become wetter and summers may become drier. Milder temperatures will affect birds, insects and plants. Pests normally killed by cold weather may survive at higher rates. Life cycles of plants, insects and animals may alter with changing weather patterns. Many animals depend on the flowering and fruiting of plants for food, so climate changes could alter these animals' foraging and breeding patterns.
Changes may be gradual. Some plants may adapt; others may not. In some areas, planning ahead will make a difference. With trees, paying attention to their provenance (where they were grown) can be important now and may become more important in the future, because research has shown that seedlings from southern populations may handle summer heat better than northern-grown seedlings of the same species. Other choices may also need to be made. For example, cold-loving species such as sugar maple (Acer saccharum) may no longer be viable choices for warming regions.
What are some of the changes we might expect? Earlier flowering times, a longer growing season with delayed autumn leaf fall and extended, late-season flowering may result from increasing temperatures.
As hardiness zones shift, it may become easier to successfully grow frost-tender plants. On the other hand, wet winters may make it more challenging to grow bulbs, tuberous plants and Mediterranean plants that depend on good drainage. Cold-hardy plants that require a chilling or dormancy period could suffer from temperature change.
As Gardeners, What Can We Do?
One obvious step is to be mindful of our energy consumption (carbon emissions), which is the cause of global warming.
Plant appropriate trees wherever possible. Deforestation contributes to the "greenhouse effect."
Look to drought-tolerant plants that can handle dry summers and rising temperatures (not exclusively--diversity is important).
Create wildlife gardens that include nectar plants, seed heads, berries, shelter and water.
Follow environmentally sound gardening practices, including composting, good site analysis and plant selection, correct pruning and mowing, good watering practices and proper sanitation.
In the garden, biological, environmental and cultural factors all contribute to the success or demise of a plant. Biological factors are pests, diseases and competition from other plants. Environmental factors are irrigation, soil amendments, fertilization and pruning. Through good gardening practices we can constructively address these issues.
Tips for Good Gardening Practices
Remember the old maxim, "the right plant in the right place." Don't try to work against nature, work with it. If you have a shady location, plant a shade garden. If you have heavy clay soils, avoid plants that need good drainage. Soil can be amended, but only to a certain extent. If your plant is well situated, you'll have a happy, healthy plant.
Look around your area to see what grows well. Remember to keep an open mind and to experiment. Every garden has its own unique micro-climate and situation. Have fun discovering what works in your space.
Look for disease-resistant cultivars. There is such a wide selection to choose from these days that gardening with disease-resistant cultivars is easy.
Start with a healthy plant. When purchasing plants at a garden center, inspect them for pest and disease problems. Buy a young, robust plant with healthy foliage rather than choosing the one that is covered with flowers. You are selecting for a plant with a good root system that will establish quickly.
Planting during the correct season will also ensure a healthy plant. For the vegetable garden, this means cool-weather crops in the spring and fall and warm-weather crops once the last chance of frost is past. Plant perennials, shrubs and trees in the spring and fall, not during the intense heat of the summer.
Proper spacing is important. Overcrowding can create shady, damp areas that are ideal environments for pests and disease.
Proper watering is also important. If you have an overhead water system, water in the morning to allow foliage to dry. Most plants need an inch of water a week (1/2 gallon per square foot). Many established plants need supplemental watering only during prolonged periods of dryness. Remember to check the soil to a depth of a few inches to see if you need to water.
Remember not to over-fertilize your plants. Over-fertilizing damages plants and causes a buildup of salts in the soil. Avoid high-nitrogen fertilizers, which produce flushes of young, tender growth that attract pests. Compost and organic material are the best ways to enrich your garden soil. Add 1/2 to 1 inch of compost to your garden in the spring. A second application can be spread later in the year, after fall cleanup.
Mulching suppresses weeds, retains moisture and adds organic material to the soil. Once the soil has warmed up and after a good spring rain, apply 2 to 3 inches of mulch. Avoid mulch "volcanoes" (piling mulch too high) and never pile mulch up against the base of a plant (it keeps in too much moisture and encourages infection).
Good pruning opens up a plant, providing good air circulation, giving the plant room to grow and helping to prevent diseases. Remember to remove dead, damaged and diseased branches.
When planting a vegetable garden, remember to rotate your crops. Different crops have different nutrient requirements. Rotating your crops will ensure that certain nutrients don't get depleted in your soils. Also, diseases and insects overwinter in soil. Many of them are specific to certain crops. Crop rotation prevents the buildup of these pests and diseases.
Companion planting and plant combinations are better than mono-cultures. Disease and pest problems spread rapidly with mono-cultures, while mixed plantings tend to slow them down. Many pests and diseases are host specific and don't affect unrelated flowers or vegetables.
Avoid heavy chemicals and attract beneficial insects such as lacewings and ladybugs by planting herbs such as fennel, thyme, and dill. A productive and diverse environment will create a balanced ecosystem.
While it is important not to strip your garden bare, remember to keep it tidy. Regular fall cleanups help prevent disease and pests from overwintering. However, beneficial insects also overwinter in debris, so keep some natural areas. Let seed heads remain on perennials for wildlife and winter interest.
Recycle all organic material in your compost pile for the next season. Remember: never compost heavily diseased debris; you do not want to risk reintroducing a problem back into the garden.