Why have my wildflowers failed?

Three years ago I embarked upon an experiment to see whether wild flower matting was, as the sales blurb suggested, a better way to establish a wildflower meadow than sowing seeds.  Well, there was definitely a difference in the price and, three years on, there is a huge difference in the visual appearance of the two areas.  But why should it be, when lawns, vegetables, flowers and shrubs grow so well in my garden, that wildflowers are so very difficult to establish?

Wild flowers prefer impoverished soils

red dead nettle

 

 

There may be external reasons such as poor quality seed or awful weather but in the main, the answer almost always lies in the soil and one particular plant nutrient seems to be the culprit.  Phosphorus.

Fifteen years ago, a group of ecologists looked at the relationship between soil nutrients and plant diversity.  What they discovered was staggering.  Soils with phosphorus levels of less than 5% supported up to 60 different plant species in 100m2 of meadow.  When phosphorus levels exceeded 5% no meadow contained more than 20 species.

Now we gardeners are accustomed to adding phosphorus to our soils on a regular basis.  It’s a basic nutritional requirement for lawn grass and essential when growing flowers and vegetables but the trouble with phosphorus, is once it’s in the soil, it tends to hang about for years and years.   We can still identify soils that were last cultivated by the Romans because they contain more phosphorus than soils that have never been cultivated.

 

 

red dead nettle.  lovely for bees but
not what I wanted for my wildflower garden 

Coping with high nutrient soils

So when somebody like me tries to turn (in my case) a section of the vegetable garden and a border that used to be a rose garden into a wild flower garden, there’s a strong possibility that the amount of phosphorus remaining in the soil is going to be more than 5%.  In which case, some of the slower growing native species might be pushed out by vigorous plants like the grasses that are so important in a meadow.

So what is the answer?  Well clearly the nutrient levels need to be reduced and there are several ways to do this

  • Remove as much topsoil as possible and work with the subsoil….but be careful not to upset the natural drainage in an area.
  • Add a layer of low nutrient soil before trying to establish wild flowers.  This would work especially well in a raised bed. 
  • Use wildflower matting instead of seed – at least you will start off with a large selection of flowering plants that have already germinated and are growing strongly.  They’ve got a good chance of survival.
  • Mow regularly and remove all the cuttings.  This really is one of the most practical ways of reducing soil nutrients.  It’s a slow process but I know from personal experience that it does work.

In my garden, the wildflower mat grown on the ex-vegetable patch is by far the most successful of the two wildflower areas.  The seeded patch has reverted to red dead-nettle and yarrow.  The bees love it but I’m not impressed so that will be dug up this winter and planted with some different pollinator-friendly plants.

wild flower meadowThe wildflower mat in its first year was a bit more grassy than I would have liked but this summer it has been a delight.  Busy with bees, butterflies, moths and a host of other insects, it has offered colour, movement and a great place to just stand and watch.  Next year, I hope it will be even better.

If I could turn back time and change anything it would be to have incorporated some low nutrient soil into the area before laying the matting so that there would have been less time waiting for it to have reached this stage and, I would have done a bigger area.

This autumn I shall be expanding my wildflower area and will use the soil on the Meadowmat website.  It may increase the cost a little but I’ve already learned from the seeding vs matting experiment that the cheapest way of doing things is not necessarily the best.

 

 

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