Over the Fence A selection of horticultural tips and content - Plants

Azaleas and Rhododendrons

Garden centres and the like have rows of beautiful and very impressive Azaleas and Rhododendrons in full bloom around March to May time.

Beware when thinking of buying one though. Both Azaleas and Rhododendrons require an acid soil to do well - note require, not "would like as a special treat" or "might get by without it". They're an example of plants that are sold time and time again to die and be bought the next year to end in the same way.

Soils that these plants like are not so common place. I've seen hundreds of collections of dead sticks in peoples gardens with a Rhododendron picture label attached.

Azaleas are a bit sneakier (or try harder to please, depending on your viewpoint) they don't often die outright, but they sort of limp on for years suggesting that they might repeat their initial glory if given a bit more time. They never do of course and just end up frustrating the gardener and taking a space where a healthy and happy plant could live.

The best way to grow these is either in a raised bed where you've made the soil acidic or in large containers of acidic compost.

Beware Euphorbias!

Many people have Euphorbias in their gardens and for very good reason, their understated yellow and green "flowers" - actually bracts - are an excellent example of less-is-more and the plants that frequently have glaucous leaves are an ideal "architectural" addition to any garden.

They do have unpleasant milky sap however that can quickly inflame skin and cause a burning sensation, particularly if gets anywhere near eyes, this can last for a few days. So when you're dead-heading them, make sure you wear gloves and are very careful about getting the sap anywhere at all and wash your hands afterwards. Just to make life more difficult, the sap tends to flow out fairly copiously from both ends of a cut stem!

Don't overdo it with "fragrant-leaved" plants. 

There are certain plants that fit in this category and for some, I think that beauty is certainly in the nose of the beholder. Anything described as "unusual" is best avoided. Because most foliage doesn't smell it's easy to get carried away and think that because something is unusual that it is good.  

There is a story I came across recently where a few years ago Cambridge City Council had to do an about turn after planting a large group of Santolina. During a particularly long warm spell when the plants made lots and lots of their smelly oils in the lovely sunshine, so many complaints were received at the strong smell of "public lavatories" that they had be dug up and replaced. Shouldn't be a problem in small quantities however.

Thigmomorphogenesis

What's that about then? It is known that young plants grown under glass often become straggly due to low light and high temperatures. But when stroked for about a minute a day they become sturdier.  The thigmo-thingy is the act of stroking plants and the processes this generates in plants. 

It does have a sensible origin however in that plants that are blown around by the wind lots and so are highly stimulated, grow shorter and stouter and so more able to withstand being blown about by the wind.

Thigmomorphogenesis means responding by growth pattern to a physical stimulus.