Plant of the Month October 2016

Posted on 29.09.2016 |
Updated on 11.11.2016 |
Added in Plant of the Month

Dahlia ‘Glorie van Heemstede' AGM

I'm so glad that dahlias have come back in from the wilderness. Fashion did us a great disservice when for many years it decreed that no discerning gardener could look at them without a derisory sniff. Why else would we have voluntarily given up such a gorgeous riot of colour at such an unpromising time of year? But never mind, for firmly back in favour they are.

Co-founder and former long-time Chairman of Western Counties Group, Brenda Jones (a stalwart octogenarian who studied with Pam Schwerdt and Sybil Kreutzberger at Waterperry) stayed faithful and carried on planting her favourite waterlily dahlia, primrose yellow ‘Glorie van Heemstede' during the lean years. Now in her hilltop garden, a wonderfully primary colour scheme dominates the entrance, where the twilight blue of Aster ‘Little Carlow' and the translucent cherry of Penstemon ‘Firebird' make unexpected harmony with the soft yellow of the dahlia.

The flower form is small waterlily, with neat, overlapping petals in soft, creamy yellow. This particular yellow is always an exception for those who eschew brassy yellows, as its cool softness will partner almost anything and still look good. Graham Stuart Thomas recommends similar toned Potentilla recta sulphurea, purely because ‘it adds to our very small list of plants of this colour'. In recent times, dahlia breeding programmes have worked to produce dark leaved cultivars, often to great effect. But in this case, crisp green emphasises a feeling of freshness that is sometimes lacking at this time of year.

If you're lucky enough to have a warm, well-drained soil, then you may get away with leaving your dahlias in the ground, covered with a mulch (though have a back-up inside, just in case, and keep an eye out for slug damage in the spring). Any hint of water-logging will rot your tubers, in which case you have no option but to bring them in. Dry them off, trim the stem to 6” and store in dry compost or sand, up to the neck. Divide in the spring, ensuring that each tuber has a root and a shoot, or take cuttings of the new shoots. Dahlias that have stood the test of time tend to have robust, plentiful tubers and D. ‘Glorie' is no exception.

After planting out in late spring, pinch out at about 15” tall, to promote branching. For those with sluggy gardens, I would recommend growing on in 8-10” pots till about that size, so that plants are big enough to withstand attack before they face the open garden. There is no doubt that slugs find some cultivars tastier than others (my record is 48 on one plant, one damp evening). I'm glad to say that ‘Glorie' is not in that category. In rich soil, staking is usually necessary – I find half-moon stakes give a more natural look than canes. Don't forget that dead-heading will give you a flowering season that lasts until the frosts – do it daily and certainly every time you pass. Buds and finished flower heads can look similar – only pull off the pointed ones that squelch when you squeeze them.

You don't have to grow dahlias in the border. In vigorous and tightly packed gardens, a row across the vegetable garden, where you can keep an eye on them, is often more satisfactory. That way, you can have a concentrated burst of colour, but still have access for maintenance and picking. If you decide to use canes here, they're at just the right height to give you a nasty poke as you pick, so cover your cane tips.

Despite the drawbacks of lifting and slug damage, dahlias provide unrivalled exuberance both in the height of summer and when the garden is starting to fade. I grow several, each with its own charm (‘Arabian Nights' in deepest claret, ‘Chimborazo' in crimson and gold, ‘Pat Knight', wine red with white stamens, ‘David Howard', dark foliage and glowing orange blooms) but my favourite of all for poise and simplicity, is D. ‘Glorie van Heemstede' – she just adds a touch of class.

Posted by Gill Mullin