An increasingly popular garden plant, hydrangeas are an attractive addition to any garden. Quick growing, some Hydrangea varieties will happily grow to 15ft. Hydrangea shrubs are a great way to fill space in a garden or add definition to spaces and edging.
Flowering from early spring until early fall Hydrangeas can also be a foundation plant in your planting scheme. This guide will take you through the vital steps that you need to know to grow Hydrangea, from choosing the right variety of Hydrangeas to planting and general Hydrangeas care.
Types of Hydrangeas
Each variety of Hydrangea plant has a different set of requirements. Some Hydrangeas may like lots of sunlight while other Hydrangeas prefer shade. One variety of Hydrangeas may be best suited to growing in a container garden while another variety of Hydrangeas will be happier in a woodland garden style planting scheme.
These Hydrangea shrubs are a great way to fill space and add structure to a space. The flowers of the Hydrangea will add color to your Hydrangeas garden from spring until fall.
Before you purchase any Hydrangea plant take the time to do some research on Hydrangeas and find a variety of Hydrangeas that is best suited to your growing conditions. This will not only make your life a lot easier but the Hydrangea plant will be more likely to flourish.
Which Varieties of Hydrangeas are Best Suited to my Area?
Generally all varieties of of Hydrangeas do well if the hydrangeas are able to enjoy the morning sun and some afternoon shade.
Recently “everblooming” varieties of Hydrangeas have been developed. The most well known cultivars of Hydrangeas include Endless Summer and Blushing Bride. These Hydrangeas are suited to growing in the coolest USDA zones. These Hydrangea varieties also repeat flower during the summer.
Hydrangea Macrophylla comes in two varieties of Hydrangeas, mopheads and lacecaps. Also known as bigheads, this is the most commonly grown variety of Hydrangeas. These Hydrangeas grows in USDA zones 5-8, although gardeners in cooler climates will need to provide some winter protection. If these Hydrangeas are exposed to freezing temperatures the Hydrangeas may fail to flower.
Hydrangea Quercifolia, also known as Oakleaf Hydrangeas, will happily grow in light shade and sunny positions. As the name suggests the leaves of this Hydrangea variety resemble those of an oak tree. Hardy down to USDA zone 4b, this variety of Hydrangeas requires sunny, warm spells in order to flower profusely. For this reason these Hydrangeas are best grown by gardeners who enjoy long, hot summers. Oakleaf Hydrangeas struggles in areas that stay consistently moist.
Hydrangea Panicle such as Peegee Hydrangeas are cold hardy Hydrangea cultivars. A large Hydrangea variety, reaching up to 15ft, these Hydrangeas are hardy to zones 3a. The variety Grandiflora Hydrangeas is particularly suited to cold climates.
Hydrangea Arborescens is also known as smooth hydrangea or snowballs. The latter name comes from the Hydrangeas’ distinctive large white flower clusters. A popular garden plant, these Hydrangea flowers look similar to mophead varieties of Hydrangeas. The cultivar Annabelle Hydrangeas grows well in warm and cool climates. This variety of Hydrangeas is hardy down to zones 3a.
Different varieties of hydrangea flowers have their own attractions with different Hydrangea flower color. The bold white snowball like flowers of these Hydrangeas can really stand out against the lush green foliage of the Hydrangea plant.
How to Plant Hydrangea Shrubs
Planting correctly helps Hydrangeas to thrive and stay healthy.
Hydrangeas thrive in well draining soil. Hydrangeas also appreciate lots of organic material. Work a good quantity into the soil before planting. If your soil is heavy work in lots of homemade compost before planting. This will improve the quality of the soil and drainage, helping to prevent root rot in these Hydrangeas.
Hydrangeas also dislike being planted too deeply in the ground. Dig a hole roughly 2 foot wider than the root ball of the Hydrangeas. The hole should also be roughly the same depth as the root ball of the Hydrangea. When in the hole the Hydrangeas plant should sit level or slightly above the soil. This will keep the Hydrangeas happy.
Where to Plant Hydrangeas
Hydrangeas like full sun for half of the day. Plant your hydrangeas in a sheltered location so that it can enjoy the morning full sun but is protected from the heat of the afternoon full sun. North and south facing positions are ideal. Hydrangeas like the full sun but will also appreciate some protection from wind. Strong winds can damage foliage and flowers.
When to Plant Hydrangeas
The best time to plant Hydrangeas is in fall or early spring. This gives Hydrangeas plenty of time to establish a healthy root system before beginning to flower. Planting during the cooler parts of the day, early morning or late afternoon, will help to protect against heat stress. Keep Hydrangeas well watered until they are established.
Transplant only when the Hydrangea plant is dormant and has lost its Hydrangea leaves. This will be during the latter part of fall or winter.
Whichever variety of Hydrangeas you choose, remember to plant it in a position where it will not overcrowd other plants. Even with regular pruning the Hydrangea plant will quickly regrow. Planting Hydrangeas in a place where it won’t overcrowd other plants will save you the trouble of regular pruning.
Remember Hydrangea shrubs require lots of space to grow into. Avoid planting other, smaller plants too close because they may become smothered and stunted.
Growing Hydrangeas in Containers
Hydrangeas can form an attractive part of a container garden. Just make sure that your chosen pot is at least 18 inches in diameter. Non-porous containers will retain moisture better, helping your hydrangeas to thrive.
Dwarf Hydrangea varieties such as Mini Penny, Buttons ‘n’ Bows or Little Lime are ideal for container growing. Simply plant Hydrangeas as you would in the ground.
Watering and Feeding Hydrangea
Hydrangeas like the soil to be constantly moist. How much water the Hydrangea plant requires varies depending on the variety. Macrophylla hydrangeas require more water than other varieties of Hydrangeas. Foliage beginning to wilt is a sign that your hydrangeas requires more water. The flowers may change color depending on the soil pH level. You can check the soil pH level and adjust the soil pH depending on what colors you want.
If you find your hydrangeas require lots of water, why not try harvesting rainwater? This can then be used to water plants in the garden, saving you from running up an expensive water bill.
When watering Hydrangeas try to water only the soil around the Hydrangea plant. Damp leaves, particularly during the cool evening temperatures, can become a breeding ground for diseases such as powdery mildew.
You can purchase hydrangea fertilizer. Alternatively you can apply a general purpose 10-10-10 fertilizer. This will contain a good to high level of phosphorus, which encourages flower production.
Oakleaf hydrangeas will happily thrive with just two applications of fertilizer in April and June. The smooth hydrangea requires just one application in late winter. Other types of hydrangeas will require regular feeding through spring and early summer. Cease feeding in the fall – this will help the Hydrangea plant to enter its dormant period.
Mulching will help to keep the soil cool and moist. Organic mulches, such as homemade compost will also break down over time. As they break down, the mulch adds nutrients to the soil and giving your Hydrangeas an extra boost.
How to Prune Hydrangeas
Different Hydrangea varieties require different levels of attention. Mophead hydrangeas never need to be pruned. You simply remove the dead Hydrangea branches every fall and await new growth to emerge. Dead Hydrangea flowers can also be removed.
Be careful when pruning Hydrangeas and removing what looks like old or dead growth. Some varieties set buds on last years new growth. Pruning this away will lead to a lack of flowers on your Hydrangea plant.
Pruning Mophead, Lacecap and Oakleaf Hydrangeas
Hydrangeas set blooms on old wood, stems that have been present for at least a year. To avoid removing this season’s buds prune before August. These types of hydrangeas set buds in August, September and October.
If you are worried about accidentally pruning away Hydrangea flower buds consider growing Remontant hydrangeas. Commonly found in North America, these Hydrangeas will regenerate flower buds that have been killed by frost or cut off. Endless Summer is one hydrangea variety that does this.
Pruning Peegee and Arborescens Hydrangeas
These hydrangea plants bloom on new wood, or fresh stems. Avoid pruning Arborescens in the spring and Peegee in the summer. This is when the Hydrangeas are preparing to flower.
When to Prune Hydrangeas
Whichever type of hydrangeas you have, the plant will benefit from removing dead stems every fall or early spring. When the Hydrangeas are 5 years old cut back about one third of the living, older stems. Cut these down to the ground. This is best done in spring or summer and will help to revitalise the plant, encouraging fresh growth to emerge. Repeat this process every year.
Spent Hydrangea flowers can be removed as and when you notice them.
Cut Hydrangea flowers can look attractive on their own or as part of a larger display. Whether you are pruning these shrubs for aesthetic reasons or to create a floral display, be careful not to remove the Hydrangea flower buds.
If you are cutting Hydrangea blooms for arrangements, in June or July you can cut the Hydrangea flowers with long stems. This is because the Hydrangea flower buds for the following year are yet to set. From August onwards cut the flowers with short stems. This will ensure that you won’t disturb next year’s developing Hydrangea buds.
How to Propagate Hydrangeas
Hydrangea shrubs rarely produce seeds. Hydrangeas propagation is usually done from cuttings.
Take cuttings only from established hydrangea shrubs. Your chosen branch should be new growth that has yet to flower. New growth is lighter in color and its stem is softer.
With sharp secateurs or scissors take a cutting roughly 5-6 inches long from the tip of the stem. There should be at least 3 pairs of leaves on your chosen stem.
Remove the lowest pair of leaves down to the stem. Hydrangea roots emerge easily from leaf nodes. If the remaining leaves are large they can be cut in half.
If you wish you can dust the lower part of the Hydrangea cutting with rooting hormone and anti-fungal powder. Both are readily available at garden centers. However their application is not necessary.
Fill a small, clean pot with moist potting mix. Place the cutting in the soil down to the first pair of remaining leaves. Water lightly and place in a plastic bag. The bag shouldn’t touch the leaves of the cutting, this can cause them to rot. Use small sticks, or chopsticks to keep the bag away from the leaves.
Place your cutting in a warm, sheltered position. A windowsill away from direct sunlight and wind is ideal.
Regularly check the cutting to ensure that it isn’t rotting. Water when the top soil appears dry.
Easy to propagate, with a little practice you will be able to fill awkward spaces in your garden with these attractive Hydrangea shrubs. This will help to create definition and provide structure. Hydrangeas will also attract pollinators and butterflies to your space.
If the cutting is successful roots will form in a few weeks. To check this, gently pull the cutting from the soil. If you feel resistance this means Hydrangea roots have formed and the process is a success.
Oakleaf and Smooth hydrangea plants produce new shoots from underground stems. These can be carefully dug up and separated from the main plant. These young plants can then be transplanted and grown on as new Hydrangeas.
Flowers Changing Colors
This can sometimes be caused by ingredients in fertilizer. Organic or homemade fertilizers will rarely have this effect.
Generally hydrangea flowers change color in accordance with your soils pH level. Soil with a pH lower than 7 can cause hydrangea flowers to turn blue. If the soil is more alkaline in nature, above pH level 7, the flowers will turn pink. Kits such as the Sonkir Soil pH Meter will allow you to not only test the pH level of your soil but also monitor moisture and light levels.
One of the most fascinating aspects of these Hydrangea shrubs is how the Hydrangea flower changes color depending on the condition of the soil. With a little time and effort you can amend the soil around the Hydrangea plants, creating the color scheme you desire.
If you want to change the colors of your flowers from pink to blue you will need to add aluminium to the soil. Sulfur or peat moss can also help to turn the flowers blue. Changing the flowers from blue to pink is more difficult. To do this you will need to increase the soil’s alkaline levels.
White hydrangeas don’t change color.
Hydrangea Pests and Disease Protection
Leaf spot, powdery mildew and wilt can all appear on hydrangea foliage. Providing the plants with the correct care will help to prevent most of these problems. There are also a number of disease resistant Hydrangea cultivars available.
If cared for correctly pests and disease will rarely trouble hydrangea shrubs. Instead with their long lasting blooms, the Hydrangea plants flower from spring to fall, will become a reliable source of nectar for bees and pollinators.
Pests rarely target hydrangea shrubs. However aphids, red spider mites and others pests can appear if the Hydrangea plant is stressed. These can be washed away with an application of soapy water or a blast from a hose pipe. Again providing the proper care and attention to your hydrangea shrubs is the best form of defense.
Overwintering Hydrangea Shrubs
It is always a good idea to protect your Hydrangea plants if you enjoy freezing winters. As some Hydrangea varieties set flowers on old wood, last year’s growth they are not suitable for pruning back. Instead you will need to mulch the base well with straw, wood bark, homemade compost or leaves. This will help to insulate the plants root system. Piling the mulch as high as 12-18 around the plant. This helps to protect lower, early flowering buds.
If you are able to cover the entire plant, holding the mulch in place with a cage made from chicken wire. If you are using leaf mulch, avoid maple leaves. They mat when wet, suffocating plants. Mulching sensitive plants to protect them from winter temperatures should form part of your annual fall transition process.
Wait until well past the last local frost date before removing the protective mulch.
Container plants can either be mulched or moved undercover for the duration of winter. Remember to water containers that are moved undercover.
Gardeners in cool or colder climates will need to protect the Hydrangeas during the winter months. An application of organic mulch will not only protect the Hydrangeas but as it breaks down the mulch will return nutrients to the soil. This will further benefit your Hydrangeas.
Finally hydrangea leaves and flower buds can be toxic to cats and dogs if consumed.
With the right care and attention hydrangea shrubs are a great way to add color and structure to a garden. Equally suited to container gardens and flower beds, these popular Hydrangea plants will provide you with color from spring until fall.
Elizabeth learnt to love gardening as a child in her grandparents backyard. Today, she is a trained horticulturist and has maintained a productive allotment for over 10 years. When not growing her own, Elizabeth enjoys helping other people with the plant problems. An experienced writer and editor, away from gardening Elizabeth is also a keen bird watcher, local historian and genealogist, meaning that she can often be found with her dogs exploring an overgrown graveyard.