Stylish Summer Containers

I’m hosting a workshop at Petersham Nurseries, part of a seasonal series we hold, discussing all things containers, planters, troughs, window boxes, bowls, urns … for a long-lasting, hopefully interesting, fragrant, colourful, herby, floral, edible and beautiful summer-long display.

I shall be looking back at some of the medleys we put together last summer, autumn and winter, that still have a home in the Nurseries, and perhaps update them for further longevity; have planted up two terracotta pots this week, one for sun and one for a shadier spot; and plan on planting up a couple more during the workshop.

We use a mix of shrubs, perennials, climbers, herbs, annuals, with a mix of leaf texture, shape, size and colour, sympathetic colour palettes – for the new planters I have used some soft cranberry, blues and purples mostly – I’ll write the planting lists a little later in the blog. But I also want to use something brighter, with Geums and Salvias, herbaceous Geraniums, in oranges and blues. I think I will pot up one ornate trough with a fabulous mix of Fuchsias, since it will sit under a tented canopy, out of full sun, but the choice of summer bedding, for sun or shade, is as muted, or colourful as you could wish for.

I have updated my notes for the workshop, and these are included here. I have rescheduled two earlier postings, from my late-summer and then winter container workshops last year, which should appear here alongside this new story.

Naturally at this time of year, Foxgloves feature mightily in our seasonal containers. They are planted boldly, with no other company, in many displays, upcycled galvanised water tanks, terracotta pots; our in-house gardener Anna planted up these displays above, with a crown of hazel pea sticks, mixing in Foxgloves with herbs, a blackberry , some tender bedding. She has used Digitalis at various stages of development for maximum longevity, and once all-but the last few flowers on each spike have fallen, will cut back the spent-flower heads to prevent them setting seed and encourage further flower-spikes to develop.

I hosted a workshop a couple of years ago on the topic of pruning perennials, as there are many ways of extending the flowering period of many herbaceous plants. I’m sure the notes will be in the archives somewhere. Worth a look.

This was one of my winter containers, with planting list in the blog of the same name, with the addition of a pastel foxglove to bring it up to date.

A simple pot of Geum May Tai in the Kitchen Garden

Geum Nonna contrasting with the cream and purple Digitalis.

WORKSHOP NOTES

Container Gardening for Summer

Welcome to Petersham Nurseries and this workshop looking at those plants that can enhance our summer gardens with delicious scents, flower, foliage, textural interest, drama – in the containers we choose to plant and place throughout our gardens, terraces, balconies, on table tops, on window ledges and as accents and focal points.

There is an infinite variety of materials to choose from – well if not infinite, there will be something that will be a compliment to your homes architecture and materials, as well as for the plants you choose to use.

We will look at the choice of these materials, elements of design, consideration of placement of plants and planting combinations, the evening garden, trees, shrubs, perennials, tender plants that add to our enjoyment of the months ahead.

For notes and photography from previous workshops, looking at late summer and winter planting ideas, please take a look at http://www.teddingtongardener.com my personal blog. There is a search function to help you navigate the site. Many of these earlier displays are still going strong throughout the nursery and I hope to update some of them to prolong their season of interest.

Thomas Broom-Hughes hosted our Spring container workshop and some of his designs also still have a home here at the Nurseries.

Looking around you will see a host of foxgloves in a variety of containers, massed blocks of beautiful Geums in big metal containers, with more foxgloves as accompaniments, plenty of tulips still giving their blowsy-all. At the top of the Cutting Garden are two huge terracotta pots that have been filled with, yes, more foxgloves, but plenty of herbs, annuals, blackberry and a construction of peasticks which are full of detail, flower-power, texture, fragrance, culinary use and have definite impact.

Elsewhere big pots of Hydrangea Limelight are underplanted with hardy Geraniums and Nemesia, Camellias populate the Courtyard outside of the Shop. At the entrance to The Garden Shop, one container with grasses and caramel Heuchera is still going strong, another – well I plan on moving this for our workshop, is full of silver foliage and has survived the winter beautifully.

Striking containers have been planted up with Sempervivums for the hardiest of all-year-round displays and we have shallow bowls where you can recreate this if you would like.

The point being, we practice what we preach and do take a look around the Nurseries to find inspiration.

If you have any questions during the course of the workshop, please do not hesitate to ask, myself and the Horticultural team will be on hand afterwards, in the Garden Shop and outside to help further.

We hope you enjoy this session and look forward to welcoming you again soon.

Before I go on, just to mention that it is Ham open Gardens this coming Sunday (but not I might add Peterhsam House Gardens – this is open for charity on two dates in July and September) but it will be a perfect opportunity to find further inspiration in real gardens – there were about 18 two years ago – and it is a very pleasant way to spend a few hours in the company of fellow gardener and their own private plots.

We will be picking fresh from our plant benches for our fresh summer containers to illustrate this particular workshop. The final selection has yet to be made – that is all part of the fun, choosing a container, planting style, colour palette ….

I hope to have planted them up, mostly, beforehand and will subsequently photograph them and upload planting lists and photographs on to my blog.

In advance of this, here are some pointers and information common to all container planting, with a view to making them as happy, healthy, long-lasting and rewarding as possible.

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 use three compost mixes here at Petersham – 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. It comes as a rich mix, Gold, for mulching, breaking up heavy clay soils and for some plants like roses; a multipurpose blend, seed mix and ericaceous, for acid-loving plants such as Pieris, Camellia, Rhododendron and Azaleas.

Melcourt is the only compost recommended by the RHS, and comes in two sizes, 15L and 50L, in a sustainable multipurpose mix and an

organic multipurpose blend. We also have Carbon Gold Gro-char which has added mycorrhizal fungi, activated charcoal and a mix of additional fertilisers and nutrients.

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. Melcourt will be supplying us with that soon.

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.

And I’m not forgetting that many of the shrubs, herbs and perennials we have to use can have a much longer life in the garden after they have served their purpose for the next season. Hellebores are a case in point. They need a rich, deep compost and reliable moisture, but can serve their time in window boxes and troughs, that long-term, are inadequate for their needs, but once the blooms begin to fade, in they can be placed in a permanent planting in the garden, to come

back year after year after year. Many of the bulbs you may have planted, can also be re-homed.

Beautiful, mobile, colourful, fragrant, used as focal points, to welcome you home – containers are a valuable tool for the gardener and we hope you enjoy the combinations put together today. Please feel free to ask questions or to speak to any of the horticultural green team after the talk.

If you have a favourite pot, planter or container, and would like us to plant it up for you, please do let us know. We may need a little time to choose plants with you, and to be able to pot it up, especially at busy times and at the weekend, but we would be happy to help and can discuss with you suitable choices for compost, feeds and plants. There may not be a charge for potting it up, but will review your particular situation before getting started.

I’ll make a particular point about roses, which can be excellent container plants, and we have separate notes on their care and maintenance. They are hungry, greedy and thirst things and need a rich compost, regular feeding throughout the spring and summer, regular deep watering and a sufficiently large container for their root system. For all excepting miniatures and patio roses, something at least 45-50cm deep is adviseable, with at least 50L of compost, preferably with an element of John Innes in the mix, or straight Gold Wool Compost.

Choose one of the less-vigorous roses, unless the container is truly big (I have planted up big wooden planters, 1m x 1m and 2m x 1m to great effect elsewhere). We have Lady Emma Hamilton in an ornate Poggi Ugo pot from Tuscany in the shrub section outside, so you can gauge the kind of size that will make them truly happy.

With drip irrigation, you might choose a smaller vessel. If you get the opportunity to visit David Austin Roses in Albrighton, near Telford,

they have a gravel garden with a wide selection of roses in containers that are quite spectacular. There are plenty of photographs on my blog if you want to see for yourselves. They won’t have the longevity of a rose in the ground but should give you a good 10-12 years of service, while in the ground this can be several decades or more.

Mature trees and shrubs likewise need a roomy container if the plants are to be truly happy. For seasonally changing displays, there is a much greater freedom.

One final note on our planters from Goicoechea. This is a family run firm based right down in the south of France, near St Sebastien and near the Spanish Border. Grandmother is in charge, her grandson and granddaughter very involved in the business. They own their own mountain, mine their own clay and manage every aspect of the production process themselves, using techniques hundreds of years old. They have a special heritage status accredited by the French Government.

Their clay is extremely elastic which allows them to make large vessels with very fine walls. Take a look at a video on Youtube by searching for Poterie Goicoechea to see their artisan team making these fine pieces.

I hope to get to visit them soon, to see this first hand. As much, I might add, because the vineyard next door matures their wines in terracotta, unique I think in France, so an added incentive.

If I can extend the trip and visit Provence, I might take in one of the 13 potteries that make up the Anduze brand, heirloom pieces we have right through the Nurseries and which are truly beautiful.

Time to make some travel plans I think …

PLANTING FOR SEMI_SHADE

Planting List

Melcourt Sustainable multipurpose compost, approximately 60 litres

Hazel Pea Sticks

• Brunnera Jack Frost
• Hosta Lakeside Spellbinder
• Hosta Praying Hands
• Campanula Viking
• Astrantia Star of a Billion
• Clematis Giselle
• Geraneum phaeum Lily Lovell
• Angelica
• Tradescantia Innocence
• Chocolate Mint
• Indian Mint
• Nicotiana sylvestris
• White Nicotiana
• Gillenia trifolata
• Muelhenbeckia

 

PLANTING FOR SUN

Melcourt Multipurpose Compost, approximately 60 litres

Hazel Pea Sticks

• Thalictrum Black Stockings
• Salvia Ember’s Wish
• Hollyhock Creme de Cassis
• Sweet Pea Beaujolais
• Astrantia Star of a Billion
• Erigeron karvinskianus
• Bronze Fennel
• Catmint
• Cynara (Cardoon)
• Anemone Wild Swan
• Pelargonium tomentosa
• Nepeta
• Pink Bacopa

It might not look much just now, but there is some bold foliage, tall plants and the Salvias will still, I hope, be going strong in November … I’ll report back.

In both of these containers, we have filled them to bursting, and how they look in a few weeks or months time, will be very different. We are not afraid of packing in the plants providing we can keep them well-watered and well fed – much use of liquid seaweed I should think, although we could have used slow-release fertiliser mixed through the compost, though I am a great fan of seaweed it must be said.

I might have used a climbing bean, had I grown any, or added a few Nasturtium seeds to the edges of the pots, I might yet though with these densely planted containers, perhaps that would be too much. Maybe in any new concoctions, we’ll see.

I’ll revisit this story with images and planting lists of anything I add during the course of the workshop tomorrow, plus updated photographs of the late-summer and winter containers, as there is life in these displays still and you can see how they have progressed.

A distinctive container planted up with Sempervivums, virtually indestructible, evergreen, perfect for sun or shade, with a healthy dose of neglect required.

One final thought, I might include a planted selection of houseplants. It depends how early I get in to the Nurseries tomorrow. Plants enjoy each other’s company, creating a healthy micro-climate and where plants enjoy similar conditions in terms of light, water, feeding and humidity, there is no reason why they cannot be potted up together to make a pleasing display. Of course you can group individual plants together, in their own solo pots, but I think I might try an experiment. The Calathea/Maranta group is one group, maybe with Soleirioli soleiriola (Mind your own business). Of course, succulents together make an interesting, colourful, textured group when planted together and all require pretty similar conditions. Maybe for another day.

I hope you will have found something interesting in this piece – and take time to look back at previous posts.

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Coming next, Petersham Nurseries’ 15th Anniversary celebrations on Wednesday evening, and notes for a workshop on the Scented Garden in summer and autumn.

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And just a reminder that it is Ham Open Garden this Sunday 19th May.