How to plant a winter window box
The ideal winter window box is pretty but easy to look after. And this one will last through spring until it’s time to do the summer window boxes!
I asked garden designer and GBBO finalist Jane Beedle (@janebbakes on Instagram) for her tips on creating an easy-care winter window box with maximum kerb appeal. You can find out how Jane transformed a muddy backyard into a beautiful contemporary garden (without busting the budget!) here.
First we went along to a local plant nursery, Meadow Grange near Canterbury, to shop for the plants.
The window box planting formula: thriller, spiller and filler!
All window boxes, not just winter ones, need three elements. They need some height and structure, a trailing element and, of course, colour.
This is known as the ‘thriller, spiller, filler’ formula for pots and planters.
The ‘thriller’ is the colour, the ‘spiller’ is the trailing element and the ‘filler’ is more than just a filler – it provides the height and structure.
In fact, Jane says you should choose the ‘height and structure’ elements first when you’re shopping for window box plants. ‘Then I’ll add a trailing plant, and some colour.’
We went to Meadow Grange nursery in Blean, near Canterbury to choose from a wide range of shrubs and seasonal plants. Put your plants together in the trolley to see how they would work in the window box. Think ‘thriller, spiller, filler’, although the ‘filler’ is the height and structure, which is a key starting point.
How many plants should be in a window box?
‘You need to pack a winter window box much more tightly than a summer one,’ said Jane.
‘In summer, you can leave gaps between plants and they will grow to fill the box quite quickly.
But plants don’t grow in winter, so if anything you have to over-stuff it.’
If you’re buying plants in 9cm pots, buy as many as you can and cram the window box full.
However, you can split ivy plants. Just one or two plants can provide trailing stems all the way along the window box.
What are the best plants for a winter window box?
When you’re thinking about height and structure, choose plants that won’t grow too tall.
Dwarf or miniature conifers are a good choice as are evergreen herbs, such as rosemary.
And if you’re adding bulbs to your window box, make sure they won’t grow too tall either. They will be blown over by the wind and will look too big for the container.
Jane put three choices for height and structure in her trolley to see how they worked with the cyclamen. They were miniature golden cypresses, some very small eucalyptus and also some upright rosemary.
‘Try out the combinations at the nursery’, advises Jane. Either see how they sit together in your trolley or borrow a bit of shelf space.
We lined up the rosemary, with a small stripey grass and the cyclamen. Nice, but it wasn’t exactly what she wanted.
Option 1: We tried out rosemary (now known officially as Salvia rosemarinus!) for the height and structure.
Next we lined up the golden cypress and red cyclamen with the ivy. This was vibrant. Perhaps too vibrant?
Option 2: would miniature golden cyprus offer a zingy contrast in the winter window box?
So we substituted some small eucalyptus plants instead of the cypress. Their grey-green looked beautiful with the cyclamen.
Option 3 and the final choice – a really pretty combination of eucalyptus, ivy, cyclamen, barbed wire plant (Calocephalus) and Leucothoe ‘Scarletta’, a shrub with red-tinted leaves.
Jane completed the plant choices by adding another silver-leafed plant, known as the Barbed Wire Plant to add texture and light.
Many evergreen plants make a good choice for winter window boxes. See 10 easy care evergreen pots for more suggestions.
The ‘three colour’ rule for successful window boxes
There’s a well known rule when choosing colours in window boxes. You should stick to three colours, and not to forget that green foliage is a colour. A window box is a limited space and it’s easy for it to look messy.
‘Although I think you can get away with combining a range of soft pinks, blues and purples in the summer,’ added Jane.
Red, pink OR white cyclamen are a good choice for Christmas – but not all three. Jane decided to go with red. She took care to pick out fifteen red cyclamen plants which were close in shade to each other.
Jane then added a variegated ivy as the trailing element. ‘There are more choices of trailing greenery in summer, but in winter, it’s probably going to be ivy.’
She picked out some ivy pots that were already trailing the right amount for her window boxes. ‘They’re not going to grow much at this time of year, so pick out the ivy lengths you want.’
There are three colours here – red (cyclamen), grey (barbed wire plant) and green (eucalyptus). Don’t expect the ivy to grow in winter, so decide how long you want it to trail and buy it at that
What plants are good for window boxes all year round?
If you want plants that will look good in your window boxes all year round, then choose miniature or small versions of evergreen shrubs.
Jane has kept the barbed wire plant in her window box for two years now, partnering it with spring and summer flowers.
Ivy will also grow in your window box all year round and will look good in all seasons.
As plants don’t grow in winter, the plants will stay roughly the same size. But if you leave a fast-growing evergreen shrub in your window box all year round it will grow in summer and will soon get too big for the container. The eucalyptus, for example, can easily get leggy and spindly, so it won’t work in the container for more than one year.
But the barbed wire plant (Calocephalus) will never grow beyond 2ft/60cm high. Miniature conifers also grow very slowly. There’s more about choosing conifers here.
Planting tips for container gardening in winter
Back home, Jane tipped half the compost out of her window boxes.
‘Because plants aren’t growing in the winter, you don’t need to replace all the compost,’ she said. ‘Unless, of course, you’ve got vine weevil, in which case you have to replace it all.’
Over-plant a winter window box because the plants don’t grow in winter. But you don’t need to change all the compost!
Before topping up with the new compost, she dotted some narcissi bulbs in. They’ll grow up in the spring – ‘just be careful to choose dwarf varieties,’ advised Jane. ‘You don’t want anything too tall.’
Then she topped up with soil and stuffed the window boxes as full of plants as she could manage.
Although she’d bought masses of plants, there still weren’t quite enough when they’re packed tight. She’d been hoping to fill two pots in the front garden, too, but that will have to be for another day.
Even though you’re only using a small amount of compost, make sure it is peat-free. I’ve found Melcourt Sylvagrow compost excellent and it’s endorsed by the RHS.
Should I put rocks, crocks or gravel over the drainage holes?
Window boxes, like all plant containers, need good drainage.
Your winter window box should have drainage holes in it so that rainwater can run out. Otherwise it will puddle in it and rot the roots of plants.
However, the traditional advice to put rocks, crocks or gravel over these drainage holes at the base of containers has now largely been disproved.
Many experts now say you shouldn’t add these and that they may even make drainage worse.
Don’t water a window box until…
‘Don’t water window boxes until you’ve got them up on the window ledge,’ advised Jane. ‘Or they’ll be too heavy to lift.’
The final window boxes up on the sill. Water them once you’ve got them in place.
She hoisted them into place, tidied up a few stray scraps of soil, and watered them.
How to winterize a winter window box
The point of a window box is to make your home look attractive. So you want to avoid having to wrap a window box in tarp, hessian or bubble wrap!
The first step is buy a window box that is frost-proof for your area. Terracotta can freeze and crack, so check that it will survive outdoors in your climate before buying it. Metal and plastic last better but they are colder for the plants.
Plants are more exposed to cold in a window box (and all other planters). So you need to choose plants that are exceptionally hardy for your winters.
In the US and Canada, you would choose plants that survive a winter two hardiness zones colder than usual. So if plants survive in your ground down to minus 17C/0F (Zone 7), then your winter window box should be planted up with Zone 5 plants, which are hardy down to minus 28C/minus 20F.
In the UK, we have milder winters, but you should avoid putting tender plants into a winter window box. Pelargoniums (commonly called geraniums) won’t survive outside in many parts of the UK. Nor will coleus and many varieties of fuchsia.
Check the label for hardiness before buying your plants.
How to make a winter window box last till May
‘The cyclamen probably won’t last much beyond early January,’ she said. ‘So I’ll take them out and add primulas or another early flowering spring flower. But the rest of the plants can stay there until I do my summer window boxes in May.’
In winter, plants don’t grow much. So you can take flowering plants out of a winter window box and replace them with spring flowers without disturbing the roots of the evergreen elements. This is one of the very useful tips in the Winter Pots post I also did with Jane.
Generally, a winter window box needs less maintenance than a summer one. All plants in pots get their food and water from you, not from the ground, but they don’t really grow much in winter, so you won’t have to water as often.
And most people don’t fertilise their pots and window boxes in winter. They only need feeding when growth starts again in the spring. For more about keeping your containers looking good, see Your Best Garden Pots Ever.
More container gardening tips
Arthur Parkinson’s The Flower Yard shows how you can have a vibrant flower garden, entirely grown in pots. And Alan Titchmarsh’s How to Garden: Container Gardening is a thorough and practical manual, covering everything you need to know to grow healthy, beautiful plants in pots.
I’m often asked for recommendations for gardening books, products and tools so I’ve put together some useful lists on the Middlesized Garden Amazon store, such as this Window Boxes & More list. I’ve picked out some window boxes from companies I’ve used, plus peat-free compost for planting window boxes. Note that links to Amazon are affiliate, see disclosure.
See the winter window boxes on video:
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Thank you, Alexandra.
Over the years, I’ve always found your newsletters very informative and inspiring.
Thank you!
Can you tell me what to do with my lovely trailing geraniums over the winter, do I need to put them somewhere and cut them back? Will they be any good next year?
Hello,there! yes, cut them back and put them somewhere cool but frost free or a cool room indoors and they should be OK for next year, though change the potting compost in spring and give them a slow release fertiliser.
Good Morning Alexandra,
Thank-you so much for your videos and posts. Regarding the above, I particularly like that window box you featured. I was wondering where to purchase these.
Best regards,
Jacqui
I don’t know exactly where Jane got these, but this company has similar planters: http://www.capital-garden.com/
Would eucalyptus be hardy enough in the north?
Eucalyptus varies in how hardy it is, depending on variety, but generally, if it’s sold in the UK, it’s hardy enough for all UK winters. There should be more information on the label, too, and you could check with the plant nursery or garden centre.
Tips for windowbox were helpful and inspiring. Many thanjs
Thank you!