One of the glories of the Wisley trials field in early summer are the delphiniums. Tall and magnificent - taller than they ever get in most people's gardens, I have to say, what with all that manure - they're a real spectacle. But then after a few weeks of glory, they're gone. Or are they?

I went back to take a look at the delphinium  trial in mid September, and then finally at the very end of the month, and found some varieties again looking very impressive. OK, the quality of the individual spikes was not up to the standard of the main display but they nevertheless made a real impact.

On my first September visit ‘Ann Woodfield', blushed white, and ‘Kestrel', electric blue with a dark eye, stood out while at the end of the month ‘Jenny Agutter' (right), in rich pink, and ‘Amadeus' (above), in deep purple blue, were the stars.

So what can we do to help ensure we get a double display from our delphiniums? First, cut off the main spike as it fades and then when the shorter, slimmer secondary spikes that follow also fade away - cut the whole plant back down to ground level.

This may seem an odd thing to do in mid summer but if the plants are kept watered, and fed with a high nitrogen fertiliser if the soil is not as rich as that at Wisley, they will soon sprout fresh new leaves. These are valuable in themselves and then followed by more flowering spikes later. Be sure to look out for mildew in hot dry spells and also for caterpillar damage. Then you've every chance of getting a double delphinium display from your plants.