THERE’S NO NEED TO THOROUGHLY DEADHEAD RHODOS POST-BLOOM
VEGETABLES: Liming can suppress micro-organism’s effects on cabbage, cauliflower and broccoli
Q I have some clubroot in my garden and so have spotty success with cabbage, broccoli and cauliflower plantings. I’m wondering why the kale is never afflicted with clubroot. I know many other gardens that harbour the clubroot organism in their soils, yet kale plants are not affected.
A: I’m not entirely certain why this is. Cabbage, broccoli, cauliflower and other close kin of kale are certainly susceptible. The only explanation I’ve ever heard for its immunity to clubroot is that kale is a more ancient, primitive brassica; the others are more recently developed and more highly bred. Having said that, I have seen one planting of kale with clubroot — but just once, over many years of gardening.
Gardens with clubroot in the soil can still grow cabbage family vegetables by leaving as many years as possible between these plantings in any given part of the garden and by liming generously before planting. The parasitic micro-organism that attacks the roots, causing distortions and swelling, is suppressed in soils with a pH of 7.2 or higher. Cool soils also lessen the degree of infection. Planting as early as possible helps.
Q Some of my rhododendrons have grown large, and now they are looking rather frowzy, in the post-bloom stage. I don’t see how I can remove every faded flower truss from the plants. Is it really necessary?
A: Though dead-heading rhododendrons does improve the look of the shrubs for the summer, it is not absolutely necessary. On very tall plants, it is not even possible to deadhead the whole thing, unless you have access to a skyhook or you’ve perfected the art of levitation.
I do try to clean up the appearance of my rhododendrons, at least on parts that are most conspicuous, because they look so tatty post-bloom; however, I rarely find time to complete this pleasant, meditative task. Any pruning needed to tidy or tame plants should be done soon after the bloom period as well.