Wouldn’t it be wonderful to choose the best plants for the projects you’re doing in your garden or farm?

To select species that do the job – grow well whatever project you’ve got planned – veggies, living mulch, green manure, a windbreak… We’d save so much time pampering our plants and money replacements.

It’s usually not hard to find lists of plants for different projects like windbreaks, green manures and cover crops.

But this is not the best way to select suitable species.

It’s equivalent to selecting a suitable person for a job before you’ve sat down and sorted out what skills they need and what they will need to do!

Recently a neighbour 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 passion fruit vines.

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

I wasn’t surprised.

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

He hadn’t put together a Job Description to choose suitable species for his living mulch.

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

In fact, anywhere there’s a climbing frame.

Writing a job description doesn’t take long. You will come up with a selection criteria that will make a big difference to the success of your project.

Here’s an example for Green Manure

The job of green manure plants is to protect and improve soil, and reduce the growth of undesirable plants.

Green manure plants therefore need to grow fast, produce masses of plant biomass to increase organic matter levels in the soil, and rapidly cover the soil. With a dense cover of green manure plants, undesirable plants (weeds) find it difficult to germinate and grow in the low light levels underneath.

An additional, though not essential skill, is the ability to fix nitrogen by having nitrogen-fixing bacteria in their roots. Other desirable criteria could be 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 the following selection criteria:

Essential criteria

  1. Grow quickly
  2. Produce dense ground cover
  3. Grow heaps of biomass

Desirable criteria

  1. Able to fix nitrogen
  2. Seeds easy to obtain and cheap
  3. Grow less than a desired height
  4. Grow deep roots
  5. Running plants on larger sites
  6. Set seed about the same time

Would you have thought of the last two criteria?

Using running plants saves money. You need less seed to cover the site.

When I grew my first green manure crop, I didn’t think about the need for the plants to set seed about the same time. Consequently, the millet seeded early and I had it coming up amongst my veggies for years afterward!

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

Another very essential selection criteria

There is an additional selection critieria that I have left out. Can you guess what it might be?

It’s essential whatever your planting… Any guesses?

Answer – will your candidate species grow well in your growing conditions?

Will they be  happy plants?

This is crucial.

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

Your green manure crop will be a flop!

You can quickly get to know your growing conditions using a GrowMap.

No special skills are required!

Now you know how to choose the best plants for the job!

Putting together a job description doesn’t take long. You’ll save heaps of time and money on expensive mistakes.

So next time you’re doing some planting, grab a cuppa or a cold beer and put together your job description and selection criteria.

Then ask  your friends and neighbours, check in books, websites, seed and plant stockists, for suitable species.

Select plants that will:

  1. Grow strong, healthy, and independently in your growing conditions
  2. Diligently perform the duties you have specified in your job description
  3. Provide extra value like decompacting your soil and attracting beneficial insects

AND don’t forget…. they need to behave themselves by not scrambling all over your other plants!

Happy planting!

Image of Phacelia by Evelyn Simak          Lead illustration © BioDivLibrary

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