Wouldn’t it be wonderful to choose the best plants for the job that needs doing?

To select species that grow well whatever project you’ve got planned – living mulch, green manure, a windbreak… We’d save so much time and money retrofitting expensive mistakes.

Most websites, books, and friends supply lists of potential species. That’s useful.

But it’s not the best advice.

It’s equivalent to someone sending you candidates for a job vacancy before you’ve sat down and sorted out what job they need to do.

Recently a neighbor of mine was telling me how he had tried growing living mulch. He’d brought a bag of Cowpea and Lab Lab (Dolichos Bean) seeds, and spread them under his vines.

It hadn’t worked he said. “It was more trouble than it was worth; plants climbing all over my passion fruit vines.”

I wasn’t surprised.

Cowpeas will climb when they get the chance, and LabLab is a vigorous legume, with a strong preference to being upwardly mobile!

He hadn’t worked out the Selection Criteria for his living mulch species list.

If he had, he would have listed ‘inability to climb’ as one of his Selection Criteria. Any plants with a partiality to climbing are defintely not suitable candidates for passion fruit trellises.

In fact, anywhere there’s a climbing frame.

Writing a job description for your planting projects doesn’t take long.  I guarantee in the process that you’ll come up with one or two additional selection criteria that will make a big difference to the success of your project.

Let’s look at an example – creating  a Job Description and Selection Criteria for Green Manure

The job of green manure plants is to improve soil health and reduce unwanted plants (weeds).

The plants have got to grow fast, quickly providing a protective soil cover, growing masses of biomass and increasing soil nitrogen levels.

Additional desirable, but not essential skills: deep roots to till the soil and pull up nutrients, and flowers producing pollen and nectar to feed beneficial insects.

From this Job Description I put together these Section Criteria.

  1. Grow quickly
  2. Grow heaps of biomass to add carbon to the soil
  3. Includes plants with nitrogen-fixing bacteria
  4. Grows a dense canopy – unwanted plants (weeds) find it difficult to germinate and grow in the low light levels underneath
  5. Seeds are cheap and easy to obtain
  6. Grow less than [a desired height]
  7. Grow deep roots
  8. Non-climbing
  9. Running plants on larger sites – need less seed to cover the site
  10. Set seed about the same time – we don’t want some plants setting seed early and then germinating and growing up amongst our vegetables

Have I forgotten anything?

Would you have thought of the last two criteria? I didn’t think of number (10) when I grew my first Green Manure, and had Millet coming up amongst my veggies later on!

select plants like this one
Lacy Phacelia (Phacelia. tanacetifolia) is a popular green manure species. It is native to the arid southwest region of the USA and Mexico


There’s also one BIG Selection Criteria I have left out

Can you guess what it might be? It’s an essential criteria to include whatever your project.

Any guesses?

Answer – will the candidate grow well in your growing conditions? Will it be a happy plant?

It’s the most crucial selection criteria.

If your growing conditions (soil, shade, drainage, etc.), don’t meet the needs of the candidates you have selected, they won’t grow well and get the job done.

Your Green Manure Crop will be a flop!

So next time you’re venturing out on a planting project, hold off from grabbing a species list

First put together your Job Description and Selection Criteria.

Select plants by choosing candidates that will

  1. Grow happily in your growing conditions (create a GrowMap)
  2. Diligently perform the duties you have specified in your Job Description

And behave themselves by not scrambling all over your other plants!

It won’t take long to put together. Enough time to have a cuppa.

Now you’re ready to ask friends, check books, websites, seed and plant stockists. You know exactly what you are looking for!

Happy planting!

Image of Phacelia by Evelyn Simak          Lead illustration © BioDivLibrary

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