These are all subjects for discussion at a workshop at Petersham Nurseries later this week focusing on winter containers and the choice of plants and planting combinations that should look good in the cooler, darker months ahead, with colour, leaf, texture and drama – and where the pace of excitement can be stepped up over the Festive Period with the addition of branch and twig, making them perfect vehicles for a fairy light or twelve. I do plan on making up, in the workshop, some smaller alternatives though I reprise some of the planters that are still going strong from my last venture into container planting, in late-Summer, and these are all still resident on site and worthy of inspection. But to look at the first three containers ….
Container Number One – limes and purples, with red dogwood
I wanted something bright, a little autumnal but that would have the ability to look good right the way through winter, bright even on a dull day. The lime Escallonia Glowing Embers looks electric against the dark leaf of the Skimmia rubella and contrasts with the Euphorbia Ascot Rainbow and the ruby Erica gracilis. Ajuga Braun hertz will continue to trail and there is a softer Ajuga, in greys and mulberry that nod towards the colours in the Euphorbia and the Cape Heath. More brightness from the evergreen variegated Euonymus contrasting with the richness of the Heuchera, also keeping its leaf throughout winter. It is a little hidden but should shoulder through to make a bigger presence. The pot is pretty full but the edges will soften. The red flower buds on the Skimmia will over many weeks slowly open to creamy white flowers, fragrant with honey scents and a rich source of nectar for early pollinators. I might have used a lime-leafed Choisya Aztec gold, to a similar effect to the Escallonia, or a lime grass like Milleum effusum, or Hakonechloa macro Aurea, though I do like the Escallonia here.
I wanted to add some height, but also make a change from the unadorned plants you might have on their own for a few weeks more, before turning up the festive volume and adding the red stems of Cornus alba Sibirica, the red dogwood makes that play and change of scale. There isn’t room in the pot for a full-sized plant, so these are cut canes speared in to the compost. Add fairy lights and that is a welcome Christmas festive planter.
The sparkly seedbeds of the Panicum Shenandoah also add a little height and the winter colours will develop on this pretty grass. Having used grasses in this next container, I didn’t want to use the same emphasis here, but it has to be said that so many grasses are perfect for a long-lasting winter display. The deciduous grasses remain as desiccated but still structural statements, being cut back in early Spring to resprout. The evergreen grasses simply need to be combed through to remove any dead or damaged growth at the same time of year, allowing for new growth to appear.
Japanese Hakone Grass
I used this image in the last workshop but it deserves to be shown again – featuring Japanese Hakone Grass, Hakonechloa aurea macra. It is deciduous, and is a dull golden brown throughout winter, but retains this superb grace. I have a pot of it at home, in a shady spot, that I love. Plain green, lime or with a cream or white stripe, the effect is never less than beautiful.
Container Number 2 – with grasses
Quite a lot wilder though again in a muted terracotta pot, the drama and dynamism being created by the several tall grasses. Anemantheles, the Pheasant Tail Grass is evergreen, turning to burnished reds and golds as winter’s temperature falls. A Miscanthus, Ferne Osten, has silky seedbeds. Carex buchanii is a permanent rusty bronze that is picked up with the paired ruffles of Heuchera Marmalade, with muted pink undersides to the leaf. Heuchera are an exceptional plant for the winter container though I have mentioned elsewhere the curse of the Vine Weevil and what you can do to prevent its triumph over your beloved containers. Carex testacea is a brighter green grass I should add, indeed I did, with a shorter finer leaf and each grass is distinguishable from one another. A small-leaved ivy and Muelhenbeckia trail, while the grasses hide and reveal the few brightly coloured Cyclamen. A little birch, again just cut stems, gives a little height, a different texture and some support for the grasses.
Container Number 3, with silvery grey and birch
I wanted a colour-themed palette with a nod towards Christmas – I tried this collection with the red dogwood stems but it just didn’t work so I found natural, cut and sawn lengths of silver birch. I really wanted a larger Eucalyptus but one with a small root ball, as there is a lot going on in this terracotta pot despite the controlled colour palette. To make it all a little looser, and it will be as it develops naturally, I might add longer lengths of cut Eucalyptus (I saw much in evidence at Covent Garden Flower Market earlier this week), pushing them in between the plants. They will last well throughout the weeks leading up to Christmas and the blue-grey colour of the foliage will tone, while also obscuring the more obvious stiff lengths of birch.
The big silver-leaved glory is Senecio Angel Wings. It is a relatively new introduction – I saw a maturing specimen at Exbury Gardens in the summer and it can become quite big and very beautiful. A large proportion of the plants that we have used in these first three containers are either shrubs or perennials, so can have a lengthy tour as part of these displays but can be re-homed in the garden beds and borders, so they have a future and can continue to repay your investment.
There is a Teucreum in there, which will have soft blue flowers next year and silver grey stems and leaves. A little Lamium has heart-shaped small, almost metallic leaves. If I remember I’ll take a picture of a pot on my front path, where is forms a silver curtain all around the glazed creamy white pot (with just the Lamium and the Fuji Cherry, Prunus incisa Ko-jo-no-mai). Calocephalus is an annual with the look of barbed wire while Silver Queen Thyme adds fragrance, an even smaller leaf and contrast. Sarcococca confusa, with evergreen glossy leaves and budding thread-like flowers close to the stems – this will add bulk to the scheme but over the winter months as these develop, they pack a perfumed punch that will ambush you as you head home or go out into the garden. Position this plant where you can reach it from the house. Sweet and intoxicating, it is a scent that travels.
Cineraria adds another grey twist to the story while Hellebore niger, the Christmas Rose, will be in flower for weeks to come. More Hellebores will become available as the days shorten further, and you will have the advantage of using both Hellebore niger hybrids, part of the Hellebore Gold Series, and then the oriental hybrids with their myriad colours. There is much to admire with a Hellebore, and please interrogate my blog for more details, especially of the Hellebore Gold Series and my excursion a couple of years ago to Ashwood Nurseries in the West Midlands. Hellebore HQ.
A little ornamental Kale will continue to grow, on a longer and longer stem (just pick off the yellowing back leaves from the rosette from time to time), while dark green ivy serves to anchor the planting, likewise the jaunty Muelhenbeckia. Lastly there is a blue Fescue grass, Festuca glauca, a complimentary tone but another completely different texture.
The birch stems may not be to everyone’s liking. Perhaps if I had had the right Eucalyptus, tall but not in a large pot, rather than just a few short stems, then I may have found the looseness and freedom of movement in the arrangement, but I confess to quite liking the ensemble and with the addition of fairy lights, a wintery silver Christmas is guaranteed.
Fragrance though is definitely something to consider. The little Violas like Etain has such a beautiful scent, why would you not want to use it instead of some scentless counterfeit. If I didn’t want to use Sarcococca, I might have chosen Daphne odora Aureomarginata, a smallish slow growing evergreen shrub with a flash of gilt on it’s dark green leaves. Clusters of waxy pink flowers in late winter and early Spring might just give you the best smelling shrub in the garden. For larger containers, try Viburnum x bodnantense – we planted up a pair last year and they bloomed, on bare stems, for weeks upon end through the winter months. Other Viburnums, V. burkwoodii and V. carlecephalum are also worth seeking out for scent.
(Below) Planted for the late-summer container workshop and still looking robust. Two faux bois long troughs planted with grasses, perennials and annuals. Look back over my recent blogs for details of the planting.
This is what I wrote just after they were planted up …
“In the two faux-bois troughs above, we used Heuchera again, with pansies to tone in with the dwarf Anemone Fantasy Pocohontas and the sparkling yellow Coropsis. Burgundy creeping Ajuga picked up the tones in the pansies, as well as the underside of the leaves of Heuchera. Mint added a lush green, as well as fragrance and the grass, Carex, both obscures and reveals the underplanting, and adds a dynamic touch to an otherwise static planting. I think I also added some silver-leaved Lamium to the mix. I will have to have a look at the planters in situ. Lysimachia numularia Aurea punches a little more lime into the mix and will trail.”
(Below) Planted for the bulb workshop, a little Goicoechea grey window box, with a selection of bulbs, all white, planted beneath the violas and Muelhenbeckia
(Below) A striking combination of just two plants, Heather and Muelhenbeckia, in a pedestal metal urn by the teahouse.
(Below) Also planted for the late-summer container workshop, another metal pedestal that will be happy to continue in service for a long time yet. The blue Hebe has stopped flowering, but there is still texture and contrast.
A pretty metal trough … planted for the late-summer workshop and by the outside till, still.
(Below) While the large container at the corner of the Garden Shop is still brim-full of flower from these rapacious Salvias. More are planted up in big Anduze pots by the entrance to Glasshouse 1, and will continue to flower until the first hard frosts.
There is Salvia Amistad and Salvia Ember’s Wish, with a skirt of evergreen Muelhenbeckia.
Ham Common/Petersham and Ham in Bloom
Another planter still going strong, though it was created earlier in the summer for Ham & Petersham in Bloom. It sits by the woods opposite Ham Common, a large stone horse trough 1.8m long by 60cm deep and wide. We used Carbpn Gold compost and it has thrived despite the heat of the summer, drought and a healthy amount of neglect. I photographed it on the way home earlier this week. You can search for London in Bloom for my blog on their installation and planting.
Each of these containers might very reasonably have been underplanted with spring-flowering bulbs, though for the first three I may have left a little more out, to give say, tulips a fighting chance of breaking through all of the planting. Please have a look again at my fairly recent notes on bulb planting in the garden, another workshop at Petersham Nurseries sometime last month.
I’ll be potting up some smaller containers on the day of the workshop, so shall revisit and update these details, bringing forward all of the notes I made for the last of these seasonal container workshops, on choosing the right pot, and the right plant for it, different materials, compost choices fertiliser and watering, drainage, frost proof, pot feet and where to use your containers in the garden. I really must mention Camellias, Rhododendrons and Azaleas, Hellebores … topiary, conifers, shade or sun loving? Well, plenty to think about.
Here’s a link to my late summer container workshop – much of the information is relevant and many of the plants have a much longer season of interest than you may have believed.
You might also look at my notes for the Winter Border workshop and the many posts that I reblogged (sorry about that folks) on winter plants and gardens. If a picture paints a thousand words, here’s a million …
Some of the salient points regarding container gardening I repeat here, valuable whatever time of the year, though there are special perils for the winter garden planter – and some advantages that we will look at in our workshop later this week at the Nurseries.
Choosing the right pot
It should go without saying that the pot should be large enough for the plants you have in mind! The larger the container, the greater the reservoir of growing medium, compost, fertiliser and water. Your plants will be happier and the work you would need to put in will be correspondingly easier. You don’t want to overwhelm a small specimen in a mass of compost is also true, so it is a balance.
Have an idea how long the planting is going to spend in the pot and consider the stability when potted up. A tall pot with a narrow base and a tall plant might easily topple over. If the plant is going to need a supporting stake, then you will need sufficiently deep compost to accommodate this.
Pot shape is also a factor, particularly if the neck of the container is narrower than the ‘belly’. It will be impossible to take the plant out to repot, without either breaking the pot or damaging the root ball.
The shape of the pot should compliment the shape and style of the planting – there is a balance to be made between the container and the planting.
The choice of materials is vast, with natural terracotta, stone, slate, glazed earthenware, wood, concrete, metal, plastic and resin and improvised containers all available in a wide range of classic, contemporary or quirky design. Keep to one style and one material if you are using more than one planter. But you don’t necessarily have to have exactly the same style – a selection of terracotta pots will have a family resemblance, but if rhythm is wanted, with a repetition of pots in a scheme, it is probably best to stick to the same pot throughout.
Terracotta is porous so may need more watering than glazed earthenware, metal, stone or plastic and resin. Metal containers should be insulated if they are to be placed in a sunny position, as the metal with easily heat up and hot metal will damage the delicate plant roots. Polystyrene sheeting, cardboard or the Sunday newspaper can be used to line the sides of the pot (but not the bottom). Plastic and resin and lighter than many other materials, and where weight is an issue, on a roof terrace or balcony, this might be something to consider. There are some very good choices that can on even close inspection, pass for natural terracotta, lead or stone.
Wooden planters have a more limited shelf-life once planted up, and the sides will need to be lined to protect the wood from being in contact with damp earth.
Drainage is essential and your outdoor containers should all have a hole at the bottom, which you can cover with crocks of broken terracotta, to prevent the soil from clogging up the hole. You might also consider putting a fine mesh directly over the hole, as this will prevent vine weevils, a serious pest, from getting into your planter. The adults can shelter under the crocks and set out at night to chomp on your previous plants, and the grubs live in the soil and can decimate your stock. These critters love a container and can do a lot of damage.
In winter, if the pots are standing on a hard surface such as a stone patio or wooden deck, ensure you use pot feet so that it can freely drain. Water is sticky and can freeze between the hard surface and the container’s drainage forming a plug. Irrelevant in warmer months, but a significant volume of water can build up in a container with no drainage and after a frost and below-freezing night time temperatures, will undoubtedly damage pots that are otherwise considered frost-proof. Freezing a large volume of water can cause catastrophic failure.
Compost, fertiliser and watering
For a seasonally changing selection of plants, a multi-purpose compost is generally sufficient. We used a wool compost for our workshops; the wool replaces traditionally used peat for water-holding capacity, and it is enriched with chopped bracken which is a rich source of plant nutrition.
For a permanently planted container, where plants will mature for several years, a loam (soil) based compost should be considered. John Innes #2 or #3 would be my choice. It is seven parts sterilised loam, three parts peat and two parts sharp sand, mixed with fertiliser and a little lime. The numbers refer to the increasing amount of fertiliser in the mix.
Be aware that some plants such as Camellias, Rhododendrons and Azaleas, Pieris – Blueberries too – need a lime-free Ericaceous compost. It is preferable to water with rainwater and to use an ericaceous feed, which will be labelled as such and probably contain iron.
You can blend your potting mix with grit and sand, if the plant selection needs better drainage. Perlite will do the same job but note that vermiculite has a pH of 7-8, making it unsuitable for ericaceous plants.
Watering is essential for containers. Rain alone won’t usually be sufficient to keep your plants healthy and happy – much of it will simply bounce of the leaf canopy and if it is densely planted, very little will penetrate the soil. Materials like terracotta will likewise wick moisture out of the compost.
A deep draught, periodically, is preferable to a ‘little and often’ approach. If you have a collection of plants, then you might consider an irrigation system where a number of containers are served by a series of hoses and feeders, linked up to an outdoor tap with a timer to come on once, or twice a day, usually at dawn or dusk. I have this at home and can go away on holiday with a clear conscience and without bothering the neighbours. Watering in winter should still be monitored; your plants may be less active but might still not receive the water they need from the weather.
The compost you use will help feed the plants for a few weeks, but if something is quite dynamic, flowering extravagantly, or fruiting, then some additional nutrition will be needed regularly over the life of the display. A general fertilise will contain the basic nutrients and something like tomato food is good for flowering displays as it is high in Potassium (K), as well as Nitrogen (N) for healthy leaf growth and Phosphorus (P) for root growth. I prefer liquid seaweed and this can be used as a drench, but also as a foliar feed if you put it into a sprayer. Seasonally changing displays can be fed throughout the life of the selection. For permanently planted containers with mature trees and shrubs, start in March and stop by the end of August. Winter feeding is rarely needed, in the cooler months and before the light levels and plant growth commencing in the early spring. At the first sign of new growth, on deciduous plants this is easier to detect, feed upon leaf break and then regularly throughout the season.
You may prefer to use a slow-release fertiliser, little spherical pellets that release their chemical over several months. These can be mixed in with the compost when filling the pot. Ideal for seasonal displays of winter or summer annuals, in window boxes and hanging baskets.
On the day of the late-summer container workshop, despite my comments at the time as to what should have been available, well I still had a wealth of plants to choose from and subsequently planted up several containers from the selection to hand. I am hoping to have an equally beautiful collection of plants to showcase for the winter container workshop, though I have already made some progress in planting up these three new containers, and maintaining those from September that still have the drive to continue into the months ahead. And I’m not forgetting that many of the shrubs, herbs and perennials we have used can have a much longer life in the garden after they have served their purpose for the next season.
I would urge you to look through recent posts and reposts on my personal blog. It has energised me to revisit some of the gardens that showcase the very best of autumn and winter gardening and to take inspiration from the horticulturally creative and imaginative teams that have planted up not only containers but landscapes with these chill, darker months in mind. I shall see what I can do with the team at Petersham Nurseries to add to the cannon,