A new series of the programme that looks at the science behind all things horticultural.
1. It's a Jungle Out There!
In the first programme Pippa Greenwood discovers that all is not peace and calm in the garden. Plants can never take it easy - they have to be permanently alert and ready to defend themselves. Their world is one of constant threat of attack from every direction.
Pippa finds that plants aren't poisonous simply to stop being eaten - the chemicals are involved in a whole host of activities. Defense mechanisms like spines and thorns also shade plants and help conserve water. And leafy greens don't contain Vitamin C just to make us healthy - they need antioxidants as much as we do.
Pippa also meets the scientist injecting leaves to make them kill themselves - and learns the astonishing fact that the reason you can easily cut yourself on a blade of grass is because it's covered in shards of glass.
In the second programme Pippa discovers that people like Prince Charles might well be on to something, talking to plants - green things thrive in an atmosphere of increased carbon dioxide, so if you breathe on them they should indeed, grow bigger. And apparently they really respond well to being stroked!
And there are many other ways that plants communicate. Pippa discovers some ferns will only decide what sex they are when they receive signals from a potential partner. And when some plants are attacked by aphids, they send messages to friendly wasps to come and consume the enemy!
But perhaps most interesting of all is the biochemist in Devon, who's discovering the songs of plants - and Pippa is lulled by the lullaby created by proteins from clover and parsley.
In the final programme Pippa looks into such questions as to why grass is green and why leaves change colour in autumn.
Along the way she uncovers other, stranger questions: If green plants are an efficient way of absorbing light, why aren't more plants black? Why are so many winter flowers small and pale - and why do bees seem to prefer yellow flowers?
She also discovers that it isn't just the pretty things that attract pollinators - some beetles prefer plants which look (and smell) like rotting flesh. And some plants apply fakery to make themselves appear brighter than they really are - and even use "landing lights" that can only be seen in ultraviolet light to entice pollinators in.
But perhaps the most satisfying discovery of all is the tale of the scientists in Wales who have developed a grass which - no matter how badly you treat it - always stays green.
Listen again to Programme 1
