Know your onions

I don’t think I’ve come across many people who don’t like alliums. There is something so cheerful about their classic pom-pom heads and strong form and it is a sight to see them marching across a border in their serried ranks adding an upright accent in otherwise softly flowering surroundings.

A close relative of the common or garden onion, the allium is part of around 500 species and if planned carefully, it is possible to have them flowering in your garden from spring through to the early autumn starting off with one of my favourites Allium hollandicum ‘Purple Sensation’ and rounding off in September with the delicate Allium tuberosum. Purple Sensation has amazing coloured purple flowers and I have found it to be reliable year after year.

Allium giganteum is even chunkier and much taller and flowers later, which means that you can plant a succession of them. Reaching around 1.2 metres tall with a huge 15cm head. Globemaster is another of my absolute favourites with even larger 20cm heads and it can reach 1.5m. The bulbs are expensive, but I think they are a good investment. Bulbs I planted in my own garden eight years ago still return each year making them good value in the long run. They do make a huge statement and for me signal that summer is really happening!

Another good variety in my opinion is the drumstick Allium sphaerocephalon. These survive better on heavier soil. A British native they are also found in Asia and North Africa. A relative of Nectaroscordum these purple reddish flowers are incredibly beautiful and I think a valuable addition to the summer border, planted in groups for maximum impact.

Slightly later in June, the colour of Alliums changes from dark purples to paler silvery lilac. These flowers need hot dry conditions to suit their origins from the eastern Mediterranean, and central Asia, including Allium cristophii and Allium schubertii, both of these have looser globe shapes with small individual flowers radiating from the main stem.

The last allium to flower is Allium tubersosum, also known as the garlic chive. Bees love this flower and they grow very well in the vegetable garden as well as border, or can be used as an edging.

Grow Alliums in a sunny well-drained position and they will come back again and again. Plant the bulbs in the autumn to the usual twice the depth of the bulb and I usually put some small sticks in around the area where they have planted to remind myself for the following spring! During the summer deadhead the flowers if you want to, but in the case of early Alliums I tend to leave the seed heads on until later in the summer as they look very attractive.

They look fantastic planted amongst lavenders, roses, emerging from lower growing planting, either along the front of the border or the back. Throw away the rulebook and put them in a winding ribbon throughout your border starting at the front and weaving through to the back and around larger shrubs. They look particularly stunning planted under Laburnum trees, the shimmering purple flowers contrasting with the bright lemon yellow.

In my 1895 copy of William Robinson’s The English Flower Garden, it seems that he was not overly enamoured with this particular flower, describing it as ‘not an important garden family, and often with an unpleasant odour when crushed’. However, Vita Sackville West disagrees in her Garden Book: ‘I think that some of the Alliums have a high value in a June garden.’ She goes on to describe some of her favourites and states that Allium giganteum, five feet tall is generally agreed to tube the grandest of all. I bought a single one last year and am now watching it anxiously’. Who could have blame her at the price of a bulb but it’s well worth it!