How to Grow Hydrangeas
Do you love hydrangeas but would love to know how to make them thrive? These stunning plants are a favourite choice for many gardeners. With their fabulous flowers and foliage, these versatile, hardy plants are a great addition to any garden.
“Flowers are the beautiful hieroglyphics of nature with which she indicates how much she loves us.” - Goethe
Hydrangeas flower in spring and summer and can be cut back in winter or grown from cuttings. The colour is an indication of the pH value of your soil. Pink flowers indicate it is alkaline (pH of between 8 and 12) and blue flowers mean the soil is more acidic (pH of between 1 and 6 with 7 being neutral). White hydrangea flowers may change colour as they mature.
As a little bit of trivia, the name ‘hydrangea’ comes from two Greek words: ‘hydor’ which means water and ‘angeion’ meaning vessel – this is because the seedpods resemble drinking cups! So let’s look at where, when and how to plant out a hydrangea as well as their ongoing needs.
Where to Plant Hydrangeas
Location: Although hydrangeas are pretty hardy flowers, they can suffer in full summer sun or windy conditions that dry them out quickly. They prefer a partially shaded area or one that receives only morning sun. So, the best location is partially shaded or ‘dappled’ shade. All varieties will bloom and grow well in a morning sun/afternoon shade location but not in heavy shade. Try the southern side of your garden (southern hemisphere) or the northern side (northern hemisphere).
Avoid heavy shade under a tree with a large canopy - choose a partially shaded area with dappled light
Avoid planting under a tree. Tree roots will compete for the rich moist soil around the plant and there may be insufficient light if the tree canopy is large.
Space: If you only have limited space, you might consider growing them in pots or containers.
Depending on the cultivar, most hydrangeas need at least 1m2 of personal space to feel comfy and do their best but make sure you check the label first to determine the mature size of the plant.
Drainage: You will also need to consider their drainage requirements because whilst they like moist, compost rich well-drained soil, they hate ‘wet feet’! Raised beds are a good option if these are available or even a mounded position.
When to Plant Hydrangeas
If your potted hydrangea has been grown and raised in a garden nursery, it will be used to being outdoors all year so you can plant anytime.
However, if you decide to plant during a hot summer, it would be wise to time your planting for early morning or late afternoon during the coolest part of the day. This will avoid heat stress. Also bear in mind that during the hotter months of the year, the plant will need to be kept well watered to establish in its new location.
Hydrangea likes & dislikes
Likes: good drainage; dappled shade; sufficient water; moist rich composted soil; mulch and a regular feed.
Dislikes: hot sun & wind; heavy clay soils; too much shade; competing for nutrients and drying out.
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Preparation and planting
1. Anytime I transplant a plant or seedling from a pot to its new home, I give it a little TLC and find I never have any stressed plants as a result. They seem to settle into their new position quickly and although many people just pop a plant straight into a hole and cover it back up with the soil they just dug out, from experience I believe you will get better results with a little extra effort and it takes only a minute anyway.
- First, to a bucket of water, add some seaweed liquid fertiliser (check the directions depending on which brand you are using and make up a ‘strong’ solution).
- Slowly lower the pot into the bucket and allow to soak until all air bubbles have stopped coming to the surface. This may take an hour or so. Seaweed fertilisers are based on kelp, which I think of as ‘Nature’s Rescue Remedy’ and a pick-me-up tonic for plants. It provides a rich source of up to 300 trace elements needed for healthy plants and helps build resistance to pest and disease. All good reasons to invest in it! While your pot is soaking, prepare the hole.
2. Dig a hole that is twice as wide as the hydrangea’s root bulb on all sides. So if you have a 200mm pot, dig a 600mm hole so the plant has 200mm extra space all the way around for the roots to grow into. Only dig the hole as deep as the pot itself.
3. Hydrangeas love compost – it is full of nutrients, helps retain moisture and builds the organic matter in your soil. This in turn attracts worms who aerate it with their tunnels and leave you a trail of rich humus for free. Wonderful garden helpers! If you have your own homemade compost, then use that as a preference. If not, then choose a certified organic compost as this is probably the next best available alternative.
If you have any additional soil improvers on hand such as rock dust minerals, crusher dust, Epsom Salts (magnesium sulphate), sugarcane mulch, worm castings, chopped banana peel or manure – these can all add valuable minerals and nutrients to the soil that will boost your plant growth. These can be added to the hole before planting and adding the compost.
If you live in an area that doesn’t get much rainfall or you have water restrictions, your soil may need a little helping hand to retain moisture. I recommend adding some coir peat or coconut husk fibre that is available at garden centres, hardware and produce stores and even some garden sections in department stores.
It is sold as a solid dry ‘brick’ that you can soak in water and will fluff up and can be added to your soil, potting mix or mixed with compost.
It is a sustainable product as the husk fire is recycled and an economical way of adding organic matter to your garden.
Coir peat retains up to 70% of its own weight in moisture so this is a cheap addition to any garden or pot. Simply follow the directions for the amount of water to add (Tip: Always use warm water to speed up hydration or you’ll be waiting until the next day for it to absorb it all!) Try adding some liquid seaweed and about a tablespoon of Epsom salts to the water at the same time – these will be absorbed into the coir peat and act as a slow release fertiliser. Epsom salts contain a water soluble form of magnesium sulphate which assists with root development.
4. Remove the pot from the bucket and tap gently on all sides to loosen or run a knife around the edge if it appears to have been in the pot a long time. If there are roots growing out the bottom, it may be a bit pot-bound so snip these off. Place the plant in the middle of the hole and back fill firmly with the compost.
Make sure the compost only comes up to the same level as the soil in the pot.
5. Add a slow release organic fertiliser such as Organic Xtra, Organic Link, Searles 5 in 1 or Nutri-Store Gold to slowly feed your hydrangea with a balanced diet of nutrients it needs for healthy growth. If the fertiliser you select doesn’t include rock minerals, try adding some NatraMin, Alroc Mineral Fertiliser or even a sprinkle of crusher dust (available from landscape supplies and quarries). Natural (non-chemical) mineral fertilisers are a blend of crushed volcanic rocks which give vitality to soils and build correct soil structure. Rock minerals should be applied to every garden to restore mineral balance and improve plant health. It is a bit like humans taking mineral supplements because we always have minerals missing in our diet.
6. Mulch well – Because their fibrous root system is close to the soil surface, it is important to mulch well. I prefer to use a ‘feeding’ mulch which breaks down to add more organic matter to the soil – mulches such as sugarcane, hay, lucerne, pea straw, grassy mulch hay, even grass clippings (no seed heads!) will all add valuable nutrients to the soil while protecting your hydrangea from losing too much moisture from the soil. You can always apply a decorative mulch on top of this if you wish but it’s an unnecessary expense unless you prefer a particular aesthetic look.
Whilst Lemongrass is usually grown for use in the kitchen, it can also be chopped & dropped as a fragrant mulch
Watering, Fertilising & Maintenance
- To establish your hydrangea, water in well.
- On hot summer days, water well in the morning so the plant won’t wilt during the heat of the day.
- Water deeply every 3 days rather than a shallow water daily or when it is noticeably dry. This encourages deep root development. You can water with Epsom salts (1 tablespoon to a 9L watering can) monthly.
- As a rule of thumb, it is better to underwater rather than over water! They will ‘tell’ you they need a drink by wilting a little.
- In winter, cut off all the flower heads that have finished blooming six joints from the flower head. This will help them bloom beautifully the next year.
Want to learn more about Growing Hydrangeas?
- Pruning Hydrangeas - Watch this practical video on How to Trim Hydrangeas for some great tips on pruning your hydrangeas.
- How to Change the Colour of Hydrangeas – Watch this video on what to add to your soil to Change the Colour of your Hydrangeas from pink to blue or vice versa!
- How to Make Your Cut Hydrangea Flowers Last Longer – Want to make your woody stemmed hydrangeas last a week longer in your vase? Find out how to treat the stem so you can enjoy your favourite cut flower longer.
Hope you’ve enjoyed my tips about hydrangeas. For more ideas on growing flowers and fragrance in small spaces, check out Micro Gardening and Inspirational Small Garden Ideas for lots of pictures too.
Do you have hydrangeas growing in your garden or have a tip to share? If you like this post, please share it!
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Copyright The Micro Gardener 2011 – http://www.themicrogardener.com
Hello Anne…..what an amazing amount of information……thank you so much – you have gone to so much trouble to give me my answer.
I am now thinking of getting two large pots and preparing the soil etc as you suggest as the position I had decided to put them in does have …. not trees …. but two other shrubs…one a nandina and the other a “cigarette bush”. Perhaps these might not be so greedy with their roots.
I can’t wait to get started.
You’re the best.
Rosemary
Hi Rosemary
Glad the information on hydrangeas was useful. It’s better to get the position right before you transplant. Sounds like large pots might be a good idea. Hydrangeas won’t grow as big as if they are planted in the ground but you will still have the enjoyment of their wonderful flowers. Perhaps you could consider putting the large pots on wheels if you have limited space? Trolleys and wheels give you the flexibility to move them to sheltered sunlight during the day if necessary or bring them under cover etc. Just check the drainage holes in the pots you choose. Check out my article on the Pros and Cons of Choosing a Container for more information before you go shopping for your pot! Love to know how your plants go in their new pots. Keep me posted!
Happy Gardening!
Anne
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Help, I am failing with my hydrangeas. The pink flower is slowing turn blue and the blue flower is turning green (two different plants).
I planted them in pots and get watered every second day with a watering system. I purchased hydrangea blueing and pinking to try to fix the problem. I have added sulphur to the blue and lime to the pink but the pH stays around 6.
How do I fix them?
Hi Ross
Thanks for your enquiry. You might find this more detailed information in the following links helpful for your situation:
Changing the colour of hydrangeas
Why are my hydrangeas turning green?
Hope this helps.