When is it Too Late to Plant Hydrangeas?

With spring nearly over the hydrangea season is upon us. Garden centers are busting at the seams with these gorgeous shrubs just begging for you to take them home. Hydrangeas easily beautify your garden with their large flowers and attractive foliage. There are different species for every spot in your garden from full sun to deep shade. Each species offers its own unique yet stunning appeal for your gardens. 

As the temperatures begin to rise it can become tricky to install larger shrubs into your garden without running into drought or heat stress issues. This can cause the shrub to appear unattractive, lose its leaves, or unfortunately die if it is not cared for as it needs to be. 

The Long Answer

There are perks to both planting in the fall and spring. In the fall, your hydrangeas will have quite a long delay before they will begin to pump out their blossoms, giving your shrubs a good amount of time to get ready for the show.

The springtime gives active gardeners more time to keep their eye on their hydrangeas throughout the growing season to ensure they are well-watered and growing happily in their new homes.

Planting By Hardiness Zone

Each zone has a bit of a different timeline for ideal planting times. Below is a more in-depth look at the zones you may live in, with some planting timeline tips. 

Hardiness Zones 3 and 4

Growing seasons in hardiness zones 3 and 4 are short and create a few obstacles for gardeners, but they can be navigated easily with some of planning.

With the last frost not arriving until mid-May and the first frost showing up in mid-September, you only have about 4 or 5 months of ideal planting weather. 

The good news is that the summer highs are comfortable for planting, and you do not need to rush to get them in the ground before summer arrives. Aim to get your hydrangeas in the ground no later than early September!

Hardiness Zones 5 and 6

These moderate hardiness zones are where hydrangeas are happiest, but the planting timeline is a bit tighter here. The last frosts in zones 5 and 6 occur in April, while the first frosts hit mid-October. 

In the springtime, you can begin planting once your ground has fully thawed. You can genuinely plant throughout the summer in these hardiness zones, but you need to be fully prepared to stay on top of watering your plants throughout the summer.

Fall is an excellent time to plant your in hardiness zones 5 and 6. Aim for getting your shrubs in the ground by early September, so they have enough time to adjust to their new home before winter settles in. 

Hardiness Zones 7 and 8

Zones 7 and 8 are pretty different from each other, but they have similar growing seasons. These two zones are found in the Pacific Northwest, the South, and the central United States. These zones have a last frost in the middle of March and their first frost around the end of October or early November. 

Even though the summers are hot in these zones, you will still want to be focused on the frost dates when you are planting.

Try to avoid planting in July and August for the best results. If you choose to plant in the fall, try to get your hydrangeas in the ground about 8 weeks before your average first frost. This should land somewhere around early to mid-September. 

Hardiness Zone 9

This is a large and hot growing zone that takes up most of the southern states on the Gulf of Mexico and part of northern California. The average low temperatures of this zone range from 20-30 degrees. The last frost is in early February, and the first frost is in late November, which creates a very long growing season. 

The key to growing successful new plantings in hardiness zone 9 is staying away from the heat during planting time. Summertime planting should be avoided. Plant in March or October for the best results.

Hardiness Zone 10

Hydrangeas will grow a bit differently in zone 10. There is typically no frost in this area, making it an endless growing season. This does not mean that it is a planting free-for-all, especially when it comes to these temperature-sensitive shrubs.

When you are selecting a planting site in hardiness zone 10, you will want to make sure your shrubs will be getting enough shade to withstand the heat. 

Zone 10 has some of the hottest temperatures in the U.S. and takes up areas in southern Florida and southern California.

Fall is the best time to plant in hardiness zone 10. This will allow your plants plenty of time to acclimate before blooming. Plant before May to ensure that they do not suffer from heat stress. 

What Happens if I Plant Too Late?

If you missed your timeline for planting and have hydrangeas in nursery pots hanging out in your yard, do not worry – you still have options.

Summer Planting

Planting in the summer heat is not ideal for any plant, but it is possible. Hydrangeas will likely be in full bloom all summer, so mentally prepare yourself for losing this season’s flowers or at least having a less-than-ideal summer of flowers. 

Once they are planted nicely in the ground, you must focus your attention on water. Water, water, water. Hydrangeas are not known for being drought tolerant. We often find our hydrangea leaves drooping toward the ground on hot summer afternoons.

Do not worry; you can do this. If you notice your leaves drooping, get out there and water! They will benefit from a deep soaking a few times a week rather than a daily sprinkling. Leave your hose on the ground near the base of your hydrangea and let your plant take a healthy drink. 

Overwintering Potted Hydrangeas

Did you miss your planting window? Maybe you grabbed some hydrangeas from your favorite garden center at a last-minute sale and ran out of time to get them in the ground.

Either way, this is not the end of the world. They overwinter beautifully if they are given the right conditions. You will need to protect your hydrangeas from the extreme elements while allowing them to experience the cooler temperatures that the winter brings. 

Depending on what your hydrangea is growing in, you may want to put it into a growing bag or container with a little bit more insulation, such as straw or leaves.

This will protect the root system just enough. Keep your potted hydrangeas in a garden shed, garage, or basement. This way, they start their growth cycle where temperatures are cool, but the stalks and roots will not be overexposed to hard frosts or snow.

On the other hand, you do not want your hydrangea to be exposed to warm temperatures for too long. This will confuse the hydrangea and cause it to push growth which the cold temperatures will likely damage. 

When spring arrives, slowly acclimate your hydrangea to the outdoor elements before planting it in the ground. Begin watering the potted hydrangea. Keep the pots outdoors for a few weeks before you plant the shrub in its new home.