GROWING HYDRANGEAS IN THE UK
Article by DavidMarks
It’s often thought that the word hydrangea comes from the Greekword for water, principally because these shrubs prefer moist conditions.However “hydrangea” is actually formed from two Greek works “hydor” meaningwater and “angos” meaning jar or pitcher.
The part of the flower which looks like a water pitcher, I think (don’tquote me!) is the seed pod.
Hydrangea macrophylla King George
Hydrangeas can range in size from 90cm / 3ft high to the size of a smalltree. However the majority are around the 1.6m / 5 ft height. Flowers aregenerally large and showy in shades of pink, red, blue and white.
Keep them watered, fed and correctlypruned and you will have a shrub that will grace almost anygarden size. For very small gardens, hydrangeas grow well in containers.
KEY FACTS ABOUT HYDRANGEAS
- They grow well in acidic, neutral and alkaline soils.
- They prefer a moist, well-drained soil. They grow well in loam and claysoils
- Prefer a semi-shade position although some varieties can be grown successfullyfull sun.
- Most hydrangeas flower from August to October, a few varieties startflowering in mid June.
- Hydrangeas in open soil are winter hardy in almost all areas of the UK.
- Several varieties are well suited to growing in containers.
- Skin contact may produce an allergic reaction for some people so gardeninggloves may be required.
WHICH HYDRANGEA VARIETY TO SELECT
Hydrangeas Come in a wide variety of colours, sizes and forms, for this reasonwe dedicated an entire page to help you select the best variety for your circumstances.
WHERE TO BUY HYDRANGEAS
Hydrangeas are popular plants which are widely available from both garden centres and online suppliers.They are also available from many non-specialist suppliers such assupermarkets. Be aware though, buying hydrangeas from supermarkets etc. maywell result in the variety not being that named on the label.
Our recommended supplier for Hydrangeas is Crocus who sell a large range of hydrangeas inpot sizes ranging from 2 litres to 12 litres.They offer a five year plant guarantee, top quality plants and excellentservice.
Click here to see and buy from their extensive range.
WHEN, WHERE AND HOW TO PLANT HYDRANGEAS
WHEN TO PLANT
Although hydrangeas can be planted at any time of year, autumn is the besttime, closely followed by early to mid Spring. The reason is that at thesetimes of year the soil will be naturally moist, a key requirement forhealthy hydrangeas.
WHERE TO PLANT
A position in semi-shade is ideal for hydrangeas, especially macrophylla andserrata varieties. They prefer morning and late afternoon sun but most will notlike being baked in the mid summer, mid day sun.
To minimise the possibility of spring frost damage, plant hydrangeas outof the way of strong winds and not in a frost pocket.
If the position can only be full sun choose paniculata or arborescensvarieties (see later down this article for recommended varieties) althoughthese will also thrive in semi-shade.
Hydrangeas vary significantly as far as size is concerned so choose aspace large enough for the eventual spread and height of your variety.
Crucial to success with hydrangeas is to plant them in an area where theywill have a plentiful supply of moisture. Don’t water log them but moisture is key.
HOW TO PLANT
If you plant hydrangeas at the correcttime and in a suitable position, planting them is easy. Simply dig a holelarge enough for the root ball so that it sits in the ground at the samelevel as it was in the container. Infill with some of the removed soil.
Sprinkle on a handful of fish, blood and bone and gently work it in witha trowel. Do not use a nitrogen rich fertiliser, this will only result inexcessive leaf growth which can easily be damaged in cold weather. Water the plant in well and cover the surrounding soil with a mulch.
CARING FOR HYDRANGEAS
Hydrangeas are relatively simple to care for, their principal needs are for a constant supply of water and feeding.
If a hydrangea runs short of water it will let you know by wilting. However,don’t let it get to this stage because each time they wilt, they loose some oftheir vigour.
How frequently to water depends on the level of natural rain, the amountof sun, the soil type and the age of the plant. In their first yearhydrangeas should be watered each week from early April to mid June, Theymay require watering twice a week from mid June to mid September. During midautumn to mid spring only water they should only require watering if thereis a shortage of natural rainwater.
In later years, they should only require watering in periods of lowerthan average rainfall, mainly during summer.
Rain water is naturally acidic to varying degrees so if your hydrangeasare blue, and you want to keep them to that colour, collected rainwater isfar better than tap water.
Feed each hydrangea with a handfulor two of fish, blood and bone in mid spring. Do not feedwith a high nitrogen feed. On light sandy soils feed again with a handfulfish, blood and bone in mid-summer.
Applying a good layer of mulch each springwill achieve two benefits. The mulch will lock moisture into the soil, italso release a low level of nutrients as it rots down each year.
HOW TO PRUNE HYDRANGEAS
Not all types of hydrangea are pruned in the same manner.
The key reason for this is that some types of hydrangea flower on stems producedthe previous seasons whereas some hydrangeas flower on stems produced in thecurrent season.
If you don’t know the type of hydrangea you will be pruning, click here to go to ourvariety page for hydrangeas and you will see clear pictures and descriptions tohelp you identify your hydrangea.
Pruning hydrangeas is not difficult at all but if you get it wrong it isquite possible to prevent it from flowering for a year. For this reason we have written a separate article about pruning hydrangeas andit can be found by clicking here.
COMMON PROBLEMS WITH HYDRANGEAS
Hydrangeas suffer from few pests or diseases.
SLUGS AND SNAILS
Hydrangeas are at their most vulnerable to slug and snail damage when the newgrowth appears in spring. Some gardens will suffer almost no damage whereasother gardens will suffer damage. There are many articles on how to preventslugs and snails and we suggest you read those because the subject is extensive.
Spring frost damage can occur inparticularly cold years, however it is very unlikely to kill hydrangeas.The damage will be brown / black leaves and shoots. Wait until the theweather warms up and the hydrangea will start to grow strongly. At thispoint prune out the damaged areas and the plant will grow well.
PURPLE LEAVES IN SPRING
If a hard frost occurs whichdoes not blacken the foliage, it can sometimes cause the leaves to turnpurple. This is a sign that the plant is under stress. There is nothing tobe done, when the weather warms up the leaves will turn to their normalgreen colour without any signs of damage.
This is an insect pest which livesoff the sap of hydrangeas. Because the insects are so small they are almostinvisible to the naked eye.
The main symptom you will notice will be small white oval “blobs” on theunderside of leaves and in some cases on the stems. These will most likelyappear in mid June to mid July. The insects crawl out from this waxycovering and migrate to the stems. The white “blobs” will remain for severalweeks although the insects will no longer be under it.
My strong advice would be to examine the undersides of the leavesregularly from mid June to mid July. At the first sign of hydrangea scale,treat the plant immediately and repeatedly (according to the instructions)with your pesticide of choice.
Before spraying, remove as many of the white “blobs” as you can. At thisstage you can effectively wipe them away although some will inevitablyremain.
We would recommend a natural and organic spray such as Bug Clear forFruit and Veg Gun or Vitax Plant Guard Pest and Disease Control.
The reason for immediate action is that scale insects are only vulnerableto pesticides when they crawl out from their white covering. Once they thenattach themselves to the stems, they form a waxy coating which isimpermeable to pesticides.
GROWING HYDRANGEAS IN CONTAINERS
Any hydrangea will grow in a large enough container but some varieties are more suitable than others.Our personal favourite for a container isHydrangea serrata Bluebird. Itgrows to a height and spread 1m to 1.2m (3ft to 4ft) in a container. See thepicture below.
Other varieties suitable for growing in containers include
Hydrangea macrophylla ‘Altona’,
Hydrangea macrophylla ‘Little Pink’,
Hydrangea paniculata ‘Skyfall’ and
Hydrangea Runaway Bride Snow White (RHS Chelsea Plant of the Year 2018).
CONTAINER SIZE AND POSITION
A minimum containersize for the varieties above would be 40cm / 16in wide and tall. Make surethat the container has adequate drainage holes in the base.
The same rules apply to the position of the container as to planting inopen ground. Aim to avoid the hydrangea being in the sun during the middleof the day but sun in the morning and late afternoon is definitelybeneficial.
Hydrangeas prefer a position protected from strong winds and this couldbe even more important for a hydrangea grown in a container. A largecontainer filled with compost and John Innes Number 3 will be a heavy objectto move. Ideally you want to avoid the need to move it for overwintering soa protected position is definitely best.
PLANTING A HYDRANGEA IN A CONTAINER
The soil mixtureshould be similar to one part of peat free multipurpose to two parts JohnInnes Number 3 compost. The hydrangea should be planted in the new containerto the same depth as it was in the previous container.
Leave 5cm / 2in between the top of the compost and top of the newcontainer. This gap can be filled with a mulch such as wood chip, gravel orsimilar to minimise water loss.
CARE OF HYDRANGEAS IN CONTAINERS
Pruning follows allthe rules as described on ourpage about pruning hydrangeas which can be found here.
Feeding is simple. A handful ofblood, fish and bonesprinkled over the surface in early spring and at the end of summer isideal. Don’t use a nitrogen rich feed, it will only encourage leaf growth atthe expense of flowers. If you want to use a liquid feed instead of blood,fish and bone, use one suitable for tomatoes.
Hydrangeas do best in a moist soil, although not a water logged one. Inthe height of summer they may well need watering daily, less at other timesof the year. Don’t judge the need for water by the surface of the compost.It’s best to stick a finger and inch or so into the compost. If it feelsdry, water; if it’s moist, it doesn’t need watering.
Below we list the key strengths and weaknesses of Hydrangeas.
|HARDY||(to -10°C / 14°F )|
|SHADE||Normally partial shade but depends on variety|
|POT / CONTAINER||Yes|
|FLOWER TIME||mid July to early October|
Other shrubs in this series include Ceanothus,
Choisya, Hebe, Skimmia, Magnolia, Mahonia, Mock Orange, Lilacs, Potentilla and
Rose of Sharon (hibiscus syriacus). Our main shrub index pagecan be seen by clicking on the link below.