Helen Yemm: Badly behaved shrubs, failing flowers and morning (un)glory
GOLDEN SHRUBS BEHAVING BADLY
We love Choisya ternata ‘Sundance’ and over the years have grown several with considerable success. Two years ago, we planted several more and half of them died. Replacements are also struggling and losing their leaves.
Brenda Commins – via email
The picture that accompanied your email told me a lot – namely that, despite previous success, this time you have chosen to plant your young choisyas in a site that is totally unsuitable for them.
The variety name ‘Sundance’ is a bit misleading. All golden-leafed shrubs (Philadelphus coronarius ‘Aurea’ is a notorious other) grow better in dappled shade, where their leaf colour is at its most eye-catching and illuminating, and in fact their leaves will scorch or bleach out and fall if they are planted where they receive a blast of full, midday sun.
I am afraid there is more: your small plants have a slate mulch over the ground between them, which undoubtedly heats up in all that sunshine. This may not have helped with their establishment during the first year after planting, and they appear to be in a completely open position (dare I mention the Beast from the East?).
I am not sure about the answer to this if your heart is set on golden-leafed shrubs in this part of your garden. Perhaps a green/yellow compromise – Elaeagnus x ebbingei ‘Limelight’ has leathery leaves with bright variegation and is regarded as one of the toughest garden shrubs.
MORNINGS AS YET UNGLORIOUS
My mother used to grow a bucket-sized pot of amazing blue morning glory that climbed up a post outside her back door. Alas, she is no longer with us, so I can’t ask her the “tricks of the trade”, and my attempts to do the same now I have a garden have met with failure. My seedlings never seem to get going properly, just turn white and wither away. What am I doing wrong?
Emily Wilkinson – via email
I am guessing that (like most first-time gardeners) you don’t have a greenhouse, and that you raised seed on a windowsill or bought tiny plants from a garden centre.
Problems with Ipomoea tricolor ‘Heavenly Blue’ (morning glory) are usually about timing.
This is an extremely tender annual that needs the constant warmth of a greenhouse or conservatory to germinate and during its early, rapid stages of growth. Seeds should not be started off until mid-May or early June and should be subjected to as little temperature variation and root disturbance as possible.
It is not too late to have another go at growing your own in situ, now the weather is warm enough. Fill a bucket-sized pot with 50/50 multipurpose compost and John Innes No 3 and insert a tall cane for support. Stick a band of anti-snail/slug copper tape around the rim of the pot. Start off half a dozen seeds on a bed of damp kitchen roll on a saucer, the whole thing covered with cling film. As soon as the seeds germinate (a little white rootlet will appear from the pointed end of each), plant the best of them shallowly in the pot placed in a really warm and sheltered spot.
The seedlings will immediately climb and once flowering starts, a weekly feed with tomato food will be welcome. Fingers crossed for a long, warm summer.
FLOWERS THAT FAIL
A couple of emailers, Sally Taylor and L Stone, have suffered similar disappointments this year and in previous years with an azalea and rhododendron that both formed buds that looked as though they were about to open and then completely failed to do so and instead wilted, went soggy and rotted away.
These sound to me like classic cases of a fungal disease called petal blight, which can occur in damp, warm weather and often in places where there is poor air circulation. Infected flowers first show small spots, which appear water-soaked.
These rapidly enlarge, turning the petals into a slimy, grey mass that sinks limply on to the leaves below. Over a period of two or three days, a whole plant can lose all its buds/flowers, the remains of which dry and then stick to the foliage and develop black, fungal, fruiting bodies that will infect the following year’s flowering.
I suggest that both readers try to “clean up” their plants by removing as much of the remains of damaged buds and flowers as they can. Next year, from the point at which the flower buds start to show colour, they should spray their plants weekly with a systemic fungicide (eg Fungus Fighter) in order to try to defeat this nasty disease.
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