Hydrangeas: Are They Annuals, Perennials or Biennials?

If you’re anything like me, once spring hits it’s about that time to make your shopping wish list for your garden. What will you add this year? Will you try anything new? Many new gardeners think about adding hydrangeas but want to know if they will come back each year, or if you’ll have to replant them after winter. So that leads to the question: Are hydrangeas annuals, perennials or biennials?

The good news is that for many hydrangea lovers, the answer can be “all of the above” depending on your hardiness zone. But some people only want to plant them if they know they’ll return the following season.

In this article, we look at exactly that. Maybe you wishing you could add a hydrangea or two to your garden, but you may not have space? Or perhaps you might be curious if you have the time to go all in on growing hydrangea, or if it can be just a one season commitment? What happens if you plant a hydrangea in a container? Will it survive the winter in the pot, or will you have to start again next season? Let’s jump in and take a deeper look at these amazing shrubs!

Explaining Annual, Biennial, and Perennial

While you may be familiar with these terms, it’s important to understand exactly what they mean. It’s also important to understand that many plants can be perennial to specific hardiness zones, but annuals to another.

Colder climates can be a bit harsh, which isn’t always great for plants that need hotter climates. So you may find a plant as a perennial in the south, but only able to be planted as an annual in the norther parts of the country. Let’s take a deeper look.

Annual

An annual plant is a plant that completes its life cycle, from seed germination to the production of seeds within one growing season and then dies. The end goal for an annual plant is to produce seed so that the plant will be able to reproduce. Annuals will continue to flower all season long until their job is complete.The best way to extend the bloom time is by deadheading until the first frost. Marigolds and petunias are examples of flowering garden annuals.

Biennial

A biennial is a plant that takes two years to grow to fruition and then dies. Generally grown in a temperate climate. Biennial plant growth begins with seeds that produce the roots, stems and leaves during the first growing season. During the second season the plant growth completes with the formation of flowers, fruit and seeds. Many biennials reseed and then the plant usually dies. Foxglove, delphinium and stock are examples of flowering biennials.

Perennial

A perennial plant is a plant that lives for more than two years. If they are cold hardy the top growth will die back with the frost and grow back in the spring. When grown in good conditions perennials will have a nice long life. This is a very broad category of plants and each one comes with its own maintenance checklist.

Perennials are great to propagate at home. You can do this by layering right in your garden, or by taking cuttings and rooting them in some growing material. Another way to get more perennials is by dividing. Do this in the spring or fall, and your garden will keep on growing! Hostas, Echinacea, and Huchera are examples of perennials.

Hardiness Zones for Hydrangeas

Most hydrangeas are hardy in USDA zones 3-7, however you will find some types of hydrangeas are hardy up to zone 9. And some varieties actually do better in colder climates, or even in the shade.

A plant’s hardiness describes their ability to survive adverse growing conditions, most specifically how well it tolerates a harsh winter. This means that most hydrangeas can tolerate a pretty cold winter and come back blooming just as well the next season.

Hydrangeas: Annuals or Perennials?

All hydrangeas are perennials. There’s no two ways about this. It will take a hydrangea more than one or two seasons to complete its life cycle. If you were to grow a hydrangea from seed it would take two or three years until you saw a flower. That is a job best left to the growers.

To take it a step further, hydrangeas are actually woody perennials which means their stems are not the soft green of say a hosta. With tender perennials the growth will typically die back with a frost, this will not happen with woody perennials. Hydrangeas have been known to live for up to fifty years, as long as they are well cared for and have adequate sun.

Treating Hydrangeas as Annuals

You may opt to treat a hydrangea as an annual, however. Choosing a hydrangea that is not suited for your climate is a good way to accidentally end up with an annual hydrangea. In this situation your hydrangea just may not make it through the winter if it is too cold, or too hot for that matter.

 A lot of annual plants are used in window boxes or containers, this is a place where you could treat your hydrangea as an annual. You can find smaller containers of hydrangeas at florists or garden centers that would make really nice additions to your window boxes. This is also a really nice idea if you love hydrangeas but may not have the space for them in your yard. 

Now of course, I would never suggest you just throw away a hydrangea at the end of the season because you could always repurpose it in your garden. But you could absolutely do that if you wanted. It is true that if you purchase a hydrangea that has been grown in a greenhouse there is a chance that the plant will not come back the next year due to the difference in the growing climate and the living climate.

Hydrangeas in Containers

I love the idea of potting up hydrangeas to fill your large containers. You could plant one all on its own, or you could add it to a combination pot. Be sure that your containers are large enough to give the hydrangea room to grow.

Water it and deadhead it just as you would a hydrangea in the ground. Once the first frost hits you will need to make some moves with your plants. If you have your plants in a decorative container, simply move them into a non heated garage or shed.

If your plants are in a nursery pot that can withstand the cold, you can dig a hole in the ground and sink the potted plant into the hole. Do not bring your potted hydrangeas in your home over the winter. The heat in your home will confuse the plant, and it will have a difficult time re-adjusting when you put it back outside in the spring. It is very likely that the plant would not survive.