Know When to Transplant Garden Plants and Flowers for the Best Success

Whether you've bought new plants at your local nursery, germinated seedlings indoors, or want to reposition some golden oldies in a new part of your garden, you might think that transplanting them can be done at any time.

However, some key transplanting timetables are worth bearing in mind for the best success, depending on the type of plant you're growing and your local climate. Read on to learn more about transplanting flowers and plants to avoid a gardening gaffe.

Annuals

Single-season annuals are typically some of the easiest plants to transplant. Getting them in the ground as early as possible in the spring (ideally after a hardening-off period of at least 10 days to prevent transplant shock) means you’ll be able to enjoy their beautiful blooms for their full flowering season. 

However, ensure the danger of a cold snap is gone. A late frost means that tender annuals, like marigolds or begonias, may die before you've had a chance to appreciate their flowers. Half-hardy annuals, like blue sage or cosmos, can tolerate light frost, so you may be able to transplant them earlier in the spring, depending on the region you live in. Because intense daytime heat puts plants under stress, plant them early on a cloudy morning, when it’s cooler and conditions are moist.

Always check your USDA hardiness zone requirements for individual species and your region's average last frost date. And remember, you need to wait for the soil to be warm enough rather than relying on general air temperatures.

Perennials

Unlike annuals, perennials can survive for many years in your yard with the proper care and climate. Dividing perennials is an essential task at some point in their life span if you want them to have longevity and good performance. Whether you're planting new perennials or transplanting divisions, spring or fall (when there’s no danger of frost) tends to be the best time to do this. 

Because transplanting inevitably results in some root loss for the plant, it's best to avoid transplanting in the peak heat of the summer. This heat stresses out plants, and because they use more water, this is problematic when the root system isn’t as strong.

Plant spring-blooming perennials in the fall to give them ample time to establish roots before the growing season. Ideally, transplant them at least six weeks before any hard frosts arrive and while the soil is still warm. If your perennials flower during the fall months, transplanting in spring is a better plan—you don’t want to move them while they’re in bloom. Wait until a few weeks after the bloom season before you transplant them.

As with annuals, transplant your perennials early in the morning on a cloudy, damp day to allow them to adjust without coping with intense sunlight.

Trees and Shrubs

When you transplant a tree depends on the species, its size, and the type of climate it prefers. However, fall is often the ideal time. The tree's roots will benefit from cool, moist weather during this time, allowing it to settle in well before it has to search for water in the summer months. 

Spring-transplanted trees usually need more frequent irrigation, but the roots won’t have to deal with harsh winter conditions while they’re bedding in. Plus, trees with thick, plump roots (like magnolias or oaks) often don’t do well with fall transplanting. The stress of hot weather doesn’t bode well for a tree, meaning summer transplanting has limited chances of success. 

Also, it often makes sense to prune the roots ahead of time. Reducing the size of the root ball to encourage the spread of many feeder roots helps your tree settle better into its new spot. Ideally, root pruning should occur at least a year before you plan to transplant it, but it can still work if you do it just a few months ahead of time. So, if you prune the root ball in the fall, then spring transplanting is best, and fall transplanting makes sense for root balls you prune the spring before.

Houseplants

You can usually transplant houseplants at any time, and it sometimes saves a dying plant's life. Some plants like to be rootbound, but others need transplanting to a larger pot to stay healthy. Typically, repotting your plant every year or two is good practice—unless they’re slow-growing types like cacti or ZZ plants. 

Signs a pot is becoming problematically rootbound include:

• The potting medium is drying out more quickly, even in the cooler winter months.

• Roots are popping out of the pot drainage holes.

• The plant is starting to lift out of the container or drop because it’s top-heavy.

• The soil is shrinking inside the container.

• Your plant is growing much more slowly than normal.