Enhancing your Summer Containers with Repeat-flowering Plants

Are you, like me, longing for Summer? This is my birthday month and my childhood memories are of soft, misty rain as we roamed the Devon countryside picking primroses and the first cowslips (I grow them in the garden nowadays). Instead, I arrived in Devon on Good Friday to several inches of unexpected snow – the children had been tobogganing before school. Here in Gloucestershire, we cannot get onto the sodden paddock to level the ruts made when we installed solar panels and the winds that whip across us are still bitterly cold.

I am looking forward to planting my summer containers and, already, I have trays of seedlings in the cold frame but, before we turn to summer, I wanted to look back to winter and some of the plantings I liked … and those that disappointed me! 

Last Saturday I went to RHS Rosemoor, always an inspiration, and looked at their containers too. One of the lessons I brought away from the visit is that bulbs can be packed into their containers; the more dense the display, the better. The bulbs can be lifted and dried over the summer and planted again in the autumn – I tend not to replant them in containers, as they are never quite as vigorous, but they will continue to grow and flower in the border.

Summer is the time when containers give us flowers, colour and scent for months on end: often it is the first frost that signals the end of the display. Choosing the right plants is crucial for a thriving and visually appealing container. Whether you chose a single plant (such as a rose) to fill your container or a selection of complementary plants, their ability to flower continuously (repeat-flowering) is essential to summer containers. Remember the ‘thriller, spiller and filler’ maxim when choosing your plants:

• Petunias and their close relation calibrachoa: I was not a fan of petunias (I dislike the sticky flowers that needed constant deadheading) but many of the newer hybrids are smaller, multi-flowered and tumble over the sides of containers. I am a convert to colours such as lime green and deep, dark purple

• Geraniums and pelargoniums: a family of over 250 plants that includes a wide variety of species. My personal favourites are the scented pelargoniums that have pretty, scented leaves (think of ‘Attar of Roses’) and dainty flowers – I haven’t tried ‘Coca Cola’, I must admit, but many of the others appeal with names like ‘Sweet Mimosa’ or ‘Prince of Orange’. I love the regal pelargoniums with their velvety flowers and the ivy-leafed geraniums that we see tumbling over the balconies of Swiss chalets

• Begonias: a plant I have not used in my own containers, although my brother has magnificent shows of begonias in his more colourful pots – and, when I see them, I wonder why I don’t do the same. They flower for months and there are varieties that are ‘thrillers’ in the centre of a display or ‘spillers’ down the sides

• Verbenas: tumbling verbenas are a must for my containers. They come in a wide variety of colours, are good ‘doers’ and flower endlessly as long as they are dead-headed regularly. Chose any of the colours from white, through seering pink to dark violet and they will enhance the display

Foliage plants: every container needs foliage to fill it out (‘fillers’) and to contrast with the brilliance of the flowers in the planting. I use Artemesia ‘Nana Attraction’ alongside Helichrysum ‘Silver Mist’ and Plectranthus ‘Silver Shield’ to give me shades of grey. Last summer, I was delighted with the dark leaves of Ipomoea ‘Sweet Caroline’ with white marguerites in a container of black and white that comprised left over plants but proved to be one of my most successful combinations

When selecting plants for summer containers, consider their growth habits, eventual size and their compatibility with the other plants in the container – height, width, spill and colour all come into my consideration of plant combinations. There are so many more suggestions I could have made but it is the ability of the plants to thrive and repeat-flower throughout the season that is most important. I use young plants that I have grown on in the cold frame but plug plants from a supplier such as Crocus or Sarah Raven are ideal.

Chose a high-quality potting compost (I always mix grit into the compost to ensure good drainage); plant the young plants with sufficient space to allow for growth but enough plants to ensure a good display (5-10cms between plants depending on their eventual size).

I mulch all my containers with 1-2” of gravel – it retains moisture and also discourages slugs.

Regular maintenance is essential to keep containers flowering. I inspect my containers every evening as I walk round the garden: I deadhead, water when necessary and apply a liquid feed every 10-14 days (these plants are under stress as we are asking them to grow and flower all season so they do need food!).

Water your containers when the top inch of soil feels dry – give them a good soaking until the water runs out of the bottom of the container.

I have containers with permanent planting (3 large containers with Hydrangea ‘Little Lime’ and others with roses) and many that I plant up twice a year. They bring focus to areas of the garden, like the terrace that runs along the front of the barn. By planning your planting to include repeat-flowering plants, scent, texture and foliage your containers will bring joy and colour to your garden from May until the first frost.