Trees and shrubs bought from nurseries were usually dug during the dormant period. These trees can be planted in either autumn or spring, so long as they receive sufficient water. Otherwise, trees and shrubs should be planted in the autumn after they have become dormant (near the time of the first frost) or in early spring before new growth appears. If your region has mild winters, but hot, dry summers, autumn planting will give trees time to establish themselves while the weather is still cool. If your winters are relatively harsh, though, plant trees and shrubs during the spring after the snow has melted and the danger of frost has past.
Other Factors That Affect Planting Times
Frost guidelines can help determine ideal planting times, but local conditions like slopes, light levels, and frost pockets also matter. While the U.S. Department of Agriculture frost guidelines may work in New England, West Coast gardeners will want a more detailed zone map. The proximity of coastal, desert, and mountain conditions in the west mean that, for best results, each garden should be assessed individually.
High-altitude or high-latitude areas also have special requirements. In northern or mountain regions, short growing seasons mean warm-season vegetables will have a better chance if started indoors and planted in the garden three or four weeks after the last frost. However, what high-altitude summers lack in length they make up for in hot, dry weather. This means that until seedlings become established, they may need to be shaded from the mid-day sun.
Weather patterns can also vary considerably from year to year. Apart from asking local gardeners, the best way to learn the rhythm of your garden is to simply experiment and track your results. Keep your own phenology records of when wild plants flower or produce fruit and when certain insects or animals appear in the garden. It can also help to record the last and first frost dates and planting times as projected by The Old Farmer’s Almanac or your favorite gardening resource to see if they’re accurate for your garden.