Gardening: Bump in the rhodo

If we wake up early on a Saturday morning - which is usually the case with four cats and a dog waiting for the fridge to miraculously spring open - we listen to the garden show on the radio. The Partner sits up in bed with the grey cat and the radio perched on his chest, while I slouch on my pillows with the black cat on my lap and a notepad at hand on which to write down Useful Things.

For example, last week I wrote down: "1 tbsp Epsom salts/10 litres water". Now, having bought the Epsom salts, I have no idea what it was supposed to be good for. If anyone else was listening and remembers, please let me know.

However, on an entirely different tack, I do remember Simon Farrell explaining that rhododendrons sometimes wait until quite late in the spring to make a decision about whether or not they're going to flower, by which time they've already made any number of buds. It is hugely disappointing, therefore, if the decision is a negative one. Obviously, they base their decision on such matters as sun, rain and soil quality, but it would be handy to know before the penultimate moment whether anything is lacking so that it might be remedied in time for a stunning display in spring. Of course, such is not the nature of gardening.

Cut one of the buds in half and see if there's any colour in there, the garden guru recommended. Since my rhododendron - the first one I've tried to grow in this subtropical garden - was evidently still trying to make up its mind, I tossed the cat off my lap, headed out to the garden with a steak knife and performed a frontal lobotomy on a bud. Nothing. Not a whisper of a petal. No colour. Just hard green stuff. This was particularly depressing since I was just back from a trip to Canterbury, where everyone's rhododendrons had made a flowering decision in the positive, despite earthquakes and liquefaction, and were looking and smelling out of this world.

I was reasonably certain the Epsom salts note wasn't for my recalcitrant rhodo, so I consulted websites worldwide to discover what I'd done wrong.

Rhododendrons are surface-rooting plants, so if you're of a mind to weed around them, don't go digging around with a hoe or a fork or you might damage the feeding roots. OK, not guilty on that count.

Don't get obsessive about tidying up fallen leaves - they provide the perfect mulch for the rhododendron and add nutrients to the soil. Well, mine never did drop any leaves, so the jury's out on that one.

Too warm and/or too dry and your rhodo will need extra mulch like pea straw to retain moisture. Dampen the soil first and then mulch. Guilty. I watered heaps, but I didn't mulch.

If you are going to mulch, don't just chuck on any old thing. Mushroom compost, for example, is alkaline and rhodos like acid soil, so that's out. Don't use anything that depletes the soil of nitrogen as it decomposes. Keep the plant stem clear or collar rot might result.

Rhododendrons like good soil but they're not especially demanding in that regard and shouldn't need feeding unless the soil is thin and poor. If it is, add generous amounts of well-rotted compost before planting.

Rhododendrons are from climates without blazing summer days, so it's a good idea to plant under the canopy of suitable shade trees or on the shady side of the house. Having said that, it must be pointed out that I saw dozens sunning themselves relentlessly in the Canterbury heat, and looking not one iota the worse for wear.

If yours have made a positive decision on flowering this year, deadhead them when they're done by carefully removing the flower head at the base, taking care not to remove or damage the growth buds at the base of the flower shoot. Young, newly planted or transplanted bushes are especially worth deadheading.

I will be deadheading up a storm next season because, despite this year's flowering failure, I will be planting at least half a dozen new ones in the autumn. In a shady place. Without weeding. Without cleaning up the leaves. With plenty of water. With mulch. But without Epsom salts, unless someone tells me otherwise.

Top dog

Call me fickle, but as well as my infatuation with rhodos, I have another new love. It's a dogwood. I heard about  it on Saturday morning radio, too, but words could not adequately describe it and it wasn't until I saw one - well, several, actually - that I began the affair.

The unromantically named dogwood  is amongst the world's most beautiful flowering trees and does great autumn colour as a bonus.

The variety I've particularly fallen in love with is, appropriately, the wedding cake tree - Cornus controversa variegata. It's medium size with horizontal, wide-spreading branches, dark green leaves and zillions of white flowers in late spring.