From ‘Goldrush’ to ‘Buttercream’, sunflowers earn their badge of honour

THE RHS trials team work away each year to grow and assess which plants can be awarded the RHS Award of Garden Merit. You may have seen the AGM, a cup symbol, on plant labels giving the RHS seal of approval that the plant performs reliably in the garden; a good indicator the plant is likely to grow well in your own garden.

The AGM is assessed by a forum made up of gardeners, nurserymen and experts specifically chosen to judge each plant on trial. They will discuss their characteristics and performance through the year before deciding if it is worthy of the award. More than 7,500 plants have gained the title; this is reviewed periodically to see if they still deserve the accolade.

RHS Garden Harlow Carr has conducted a number of trials for plants particularly suited to our northern climate. A few years ago we trialled Meconopsis – more commonly known as the Himalayan Blue Poppy - which requires cool, moist growing conditions. Currently, we are trialling strawberries in hanging baskets in the Kitchen Garden as part of an AGM trial.

Last year it was the turn of the Sunflower, Helianthus annuus, to be assessed at RHS Garden Wisley. Sunflowers are hardy annuals, sown from seed in the spring and flowering from late July until the autumn, providing marvellous blooms through the season. Those on trial comprised three types: dwarf or container varieties, mid-sized border or cut flower varieties averaging around 2m and field-grown varieties growing to above 3m. In total, 137 varieties were grown. By the end of the trial 12 varieties gained the Award of General Merit; six of these were container types.

Here at Harlow Carr we have planted a display bed of the worthy winners in the Lakeside Gardens, bringing a little sunshine on the duller days. We managed to attain eight winning varieties including ‘Goldrush’, ‘Solar Power’, ‘American Giant’ and ‘Buttercream’. All the others are container or dwarf forms: ‘Ballad’, ‘Munchkin’, ‘Wahooh!’ and ‘Teddy bear’.

We have grown them in blocks radiating out in a sunray pattern. It has been a trial in itself as a rabbit proof fence had to be erected, not to mention the ongoing battle with the slugs and snails. We also decided to sow them in the nursery rather than direct into the bed to ensure strong plants and good flowering in our cooler climate and shorter growing season.

I’m particularly looking forward to ‘American Giant’ flowering. This impressive variety reaches 3.4 metres on average and I can’t wait to see this epic sunflower in bloom. ‘Solar Power’ has to be the most striking with its bi-colour flowers with a burnt orange centre, a truly gorgeous bloom. For novelty, ‘Teddy Bear’ is a good choice. With its unique tight double blooms looking like teddy bear fur, it is definitely the strangest looking sunflower I’ve seen.

All our sunflowers seem to be growing well and should be flowering by the end of July and into early August. Come along and see a sea of yellow in the garden.