The problem is that there is no scientific distinction between wild flowers and garden flowers. It’s true that many garden plants are hybrids or selections with sterile, double flowers and exist only in gardens. But it’s equally true that many are identical to the original wild species, even if that species is wild in Japan or America rather than in the UK.
A plant’s liking for a fertile soil depends on the sort of soil it evolved to grow in. Plants that evolved in rich soils like rich soils, so if you give them lots of fertiliser they will reward you by growing faster and bigger. Most of the world’s plants evolved in poor soils and have adapted to manage without lots of nutrients. Part of that adaptation is to grow slowly, and such plants cannot be persuaded to grow fast, however much fertiliser you give them.
The imaginary distinction between wild flowers and garden plants cuts across this divide and gardeners grow lots of both kinds. The rock garden and alpine house are populated almost entirely by small, slow-growing plants that will remain small and slow-growing however kind you are to them. On the other hand, the vegetable plot is mostly full of fast-growing plants that respond well to fertiliser. It’s also worth mentioning that, if you use lots of fertiliser you will certainly have lots of big, happy weeds.
Wild flowers and garden plants do differ, but the difference lies not in the plants themselves, but in how we try to grow them. We generally grow garden plants in quite rich soils, which would soon allow the bigger and more territorially ambitious sorts to crush their neighbours. Recognising this, we vigorously police our borders, weeding, thinning and dividing in an attempt (not always successful) to prevent the thugs from taking over.
But we generally attempt to grow wild flowers in some sort of ‘meadow’, where we give them free rein to compete not only with each other, but also with grasses. Grasses are firmly in the camp of fertility lovers, and farmers achieve huge yields of lush grass by application of buckets of nitrogen fertiliser. Mixing wildflowers with grass on typical fertile garden soil soon goes to its logical and generally unattractive conclusion; lots of grass, no flowers. (See also our page on the myth of lawn replacement.)
So, do ‘wild flowers thrive in poor soil’? No, not really, any more than you or I would thrive on a diet of bread and water. A better way to look at it is that wild flowers don’t like poor soils very much, but the grasses that would like to overwhelm them like them even less.
The answer is to treat wildflowers like garden flowers and grow them in flower beds away from nasty competing grasses. Even if the soil is fertile, they will grow happily (and some will grow a bit stronger than normal). You will however have to look after them and remove competing grass and those other wildflower thugs you choose to call weeds!
You might like to read Ken Thompson's piece on the meaning of the word "wildflower
Page compiled by Steve Head from Ken Thompson's text