Family Matters – Legumes

Joyce Russell will be looking at the pea and bean family.

Leguminosae is the official name for what is commonly known as the pea family, оr the рea and bean family. Many people also refer to these as ’legumes’. It’s convenient to have a name that embraces them all since they share so many characteristics and growing requirements. The varieties many gardeners are most interested in are: peas, including mangetout; broad beans; runner beans and French beans. You’ll find different types of delicious bean of course, but a warmer weather is required by many of these than we can supply.

Legumes produce large seeds and pods. It can be either, or both, of these features that make them good kitchen garden vegetables. The fact that plants often crop heavily, that they fix nitrogen into the soil, that the seeds are a great source of protein, and that both peas and beans taste really good, are other reasons why legumes come high up the list for most vegetable growers. On top of that, the typical pea flower – in shades from white to deep crimson – is an attractive feature for any garden.


Fixing nitrogen

Peas and beans have nodules on their roots. The nodules are colonised by rhizobacteria. These can extract nitrogen from the air and convert it into a form that is useable by the plant. This is a particularly useful symbiotic relationship and one that means peas and beans can crop well even on a soil that is low in nitrogen.

It’s often recommended that plants should be cut off close to the ground when a crop is cleared. This is so the roots can continue to release their nitrogen into the soil as they break down.

Acid or alkaline?

Legumes do best on soil with a pH of 6 5 to 7. Acidic soils can be adjusted by scattering hydrated lime or wood ashes on the soil’s surface. Both of these will be washed down into the soil and will alter the pH in the immediate environment of the roots.

Lime can be added to the bed several months before planting, but I have always found that ‘spot-treating’ rows at sowing, or planting time works just as well – the benefits aren’t washed away by heavy winter rains.

If the soil is very alkaline, add compost, manure, sulphur chips or coffee grounds. However, legumes usually do much better on an alkaline soil than they do on an acid one, so lowering pH isn’t essential.

Soil preparation

Legumes do best on a well dug, moisture retaining soil. Because these crops fix nitrogen, there is no need to search manure into the plot, but other nutrients are still needed by them. Remember that too much eating can keep at the expense of pods to plenty of leaves. Fertilizer may be the solution. This is set as a thick layer while in a trench’s bottom where water will be held by it and provide a spring supplier. Sources will soon discover their way into the compost.

Useful Link: Dry Beans, Split Peas & Lentils

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