There’s a reason so many gardeners (including myself) reach for a hydrangea (Hydrangea spp.) when we need to fill a shady spot in the landscape. Hydrangeas are hardy and diverse and capable of thriving in areas where roses and other shrubs are apt to suffer.
In this article, I break down the primary hydrangea growth stages and annual life cycle. Whether you’re a seasoned hydrangea fanatic or new to the flower, you’ll walk away with a new appreciation for this classic shrub.
- Conditions for Growing Hydrangeas
- Hydrangea Growth Rate
- Growth Stages of a Hydrangea Shrub
- Hydrangea Annual Life Cycle
- When to Cut Hydrangea Flowers
- FAQs Hydrangea Growth Stages
Conditions for Growing Hydrangeas
As a general rule, hydrangeas are ideal for USDA Zones 5 to 9. Many varieties can survive winters in Zones 3 and 4 but will struggle to produce healthy flower buds in the spring. If you’re in a colder climate, I highly recommend planting panicle hydrangeas, as they tend to be the hardest.
Hydrangeas are frequently lauded as shade lovers but, particularly in cooler climates, some varieties can also handle full sun. Too little sunlight overall can impede growth and flower development in most varieties.
Your hydrangeas will grow best in moist, well-draining soil. While these shrubs enjoy excellent, damp conditions, excess water can still place undue stress on the roots and promote fungal diseases. Oregon State University advises against using high-nitrogen fertilizers like manure.
Perhaps the most famous characteristic of the hydrangea is its colorful response to soil pH. I want to point out, however, that this phenomenon is typically only seen in bigleaf or French varieties (H. macrophylla). Such varieties will turn more pink when the soil is more alkaline and more blue when the soil is acidic.
Hydrangea Growth Rate
The average hydrangea growth rate is super dependent on the variety or cultivar. Some of the most extensive and vigorous hydrangeas can grow up to 2 feet per year! In contrast, dwarf hydrangeas may only grow a couple of inches per season.
In my experience, the most dramatic growth occurs in the first couple years of the shrub’s life. A good growing environment and proper care will encourage optimal growth in any case.
Growth Stages of a Hydrangea Shrub
Hydrangeas are perennials that can easily live for a decade or more. It takes the average shrub 2 to 5 years to mature enough to flower correctly.
1. Seed Germination
Commercially grown hydrangeas are very frequently propagated from cuttings. In nature, however, this plant most commonly reproduces via seed.
One reason many people don’t think about growing hydrangeas from seed is that the seeds are tiny. (So small that they could almost be mistaken for dirt particles.) Hydrangea seeds are naturally sown in the fall as the flower heads dry out but won’t sprout until the following spring.
Temperature and moisture play significant roles in when and how hydrangea seeds sprout. There isn’t a lot of research available on the best temperature to germinate hydrangea seeds. However, any temperature between 50 and 80°F should result in germination.
In the right conditions, hydrangea seeds can germinate in as little as 14 days.
Hydrangeas are dicots, which means that each seedling starts life with two embryonic leaves. These leaves are called cotyledons.
Cotyledons are very simple in appearance. They store energy within the seed embryo and support the seedling early in its life before it can fully photosynthesize.
A hydrangea seedling’s cotyledons are quickly replaced by the first mature leaves. The emergence of these first leaves means that the plant is now self-sustainable.
3. Vegetative Growth
As deciduous shrubs, hydrangeas will continue to get bigger and bigger until they eventually die. But the most crucial vegetative growth occurs in the first few years.
It usually takes at least 2 to 3 years for a new hydrangea shrub to flower. During this time, the plant is hard at work developing new branches — which will produce their own sets of leaves — and advancing its root system below the ground.
Most hydrangeas flower off of the tips of their branches. Some varieties, particularly those that bloom on new wood, may also flower along the length of the branches.
Hydrangeas are famously categorized as either ‘new’ or ‘old’ wood. This distinction refers to when the flower buds develop for a given growing season.
- New wood hydrangeas produce flower buds and bloom the same year. These include panicle and smooth varieties.
- Old wood hydrangeas produce flower buds that will not bloom until the following year. These plants are particularly vulnerable to harsh winters and improper pruning. Old wood varieties include bigleaf, oakleaf, climbing, and mountain hydrangeas.
5. Old Age
Hydrangeas can survive up to 50 years with perfect care. But since our gardens experience things like inclement weather, pests, and general wear and tear from the environment, a lifespan of 10 to 20 years is often more realistic.
Hydrangea Annual Life Cycle
Once established, a hydrangea will repeat the same sequence of growth year after year. Here’s a quick look at this annual life cycle:
Hydrangeas are deciduous, meaning that they lose their leaves each fall. Budding out is the first hint of growth in the spring and is a clear sign that your hydrangea survived the previous winter!
While hydrangeas tend to bud out a bit later than other trees and shrubs in the garden, their leaves come in relatively quickly once the process starts.
A healthy hydrangea will flower practically every year. Most varieties start blooming in early or mid-summer.
Many gardeners complain that their hydrangeas haven’t flowered all year. This usually happens when the flower buds are damaged or removed early in development. In my experience, the most common culprits are cold damage from the previous winter or improper pruning.
Hydrangeas typically go dormant during the cold winter months. However, at least as far as we know, this dormancy period isn’t a required part of the plant’s life cycle. (Some plants, such as many fruit trees, need exposure to cold in order to flower.)
Winter dormancy protects the shrub from cold damage and helps conserve energy for the next growing season. Hydrangeas exposed to extreme cold may show signs of dieback the following spring.
When to Cut Hydrangea Flowers
If you want to enjoy your hydrangea blooms in a vase or create a giftable bouquet, there are a few things you should know first. While hydrangeas make lovely cut flowers, they tend to wilt quickly if not harvested correctly.
Your hydrangeas won’t be ready for harvesting until at least mid-summer. The exact timing can depend on your climate and the shrub variety. You want the flowers to be open and fully colored before cutting.
Use clean, sharp pruning shears to remove the flowers you want to bring inside. I recommend cutting just above a stem node. Take a couple of leaves with the cut flower as well.
You can improve the quality of cut hydrangeas by splitting the end of the stem to allow for better absorption. Don’t waste any time getting your fresh-cut hydrangeas in some water!
FAQs Hydrangea Growth Stages
Do hydrangeas bloom in their first year?
Young hydrangeas grown from seed won’t flower right away. Instead, it usually takes at least 2 to 3 years for the first buds to form. On the other hand, hydrangeas transplanted from nursery starts will sometimes flower their first year or shortly thereafter.
- Oregon State University Soil quality for hydrangeas
- North Carolina State University Bigleaf hydrangea care
Ben's horticultural interest grew when graduating from Hertfordshire University in 1997. Having contributed to numerous publications including Better Homes & Gardens, Garden Design Magazine, and The English Garden. He is also the author of Propagating Houseplants Made Easy.