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Gardening diary: August

Gardening diary: August

Each time we harvest our fruit and vegetables we are breaking nature’s recycling system, effectively removing nutrients from the soil. So in August, while the food garden lies pretty much bare, it’s a good time to replenish nutrients. The old adage ‘feed the soil, not the plant’ applies when it comes to replenishing nutrients, the food being:

  • Nitrogen (N) for green leaf, shoot and stem growth
  • Phosphorus (P) for root growth, germination and fruit formation
  • Potassium (K) for starch and sugar formation in fruits

The best way to provide these nutrients, without risk of upsetting the delicate equilibrium found in living soils, is to layer well-rotted manure, followed by a dusting of bone meal (or blood and bone) and wood ash from untreated firewood.

Plants also need smaller quantities of, but nonetheless equally essential, minerals including calcium, magnesium and sulphur along with minute quantities of compounds which contain, boron, copper, iron, chlorine, manganese, molybdenum and zinc.

Again, in order to provide these nutrients in a sensitive and balanced way, it is best to sprinkle over a fine layer of the mineral dolomite followed by seaweed, the latter either picked from the beach, washed and thrown over the vege bed, or as one of a number of preparations available from garden centres.

Alternatively, all of the above nutrients and minerals can be provided via synthetic fertilisers. These are cleaner, quicker acting and simpler to handle but greater care must be taken in applying just the right amount. In contrast to using organic materials, too much can be harmful to plant and soil life.

Organic

PROS CONS
Increases amount of soil micro-organisms — these create plant nutrients Large quantities needed — for example, compost is low in nutrients
Encourages earthworms and other beneficial soil insects Heavy, dirty work
 
High humus content of manure and compost increases air and water soil-holding capacity Relies on micro-organisms to convert to nutrients which are slow acting, particularly when cold
Little risk of over-application  

Synthentic

PROS CONS
High in immediately available nutrients Can impede or kill soil micro-organisms
Specialised versions available to suit various plants Can acidify the soil, making it less productive
Small volume and weight
 
Will reduce humus formation — essential for air and water retention in soil
Simple to use Can be expensive
  Will kill all soil life if over applied
  Harmful to some freshwater life

Q: “How can I prevent my coriander from going to seed shortly after planting?”

Selina, Taupiri

A: Coriander is a delicate herb which grows best in autumn and spring. If growing coriander from seed, start seeds off indoors, using a good quality seed-raising mix. Plant seeds just under the surface of the mix, gently cover then water. Once they have reached about 5cm high, acclimatise them before planting them in the garden.
Choose an outdoor spot for coriander out of the midday sun because if the soil gets too warm, the coriander will quickly go to seed (also called bolting). Adding mulch as a top layer helps prevent soil getting too warm. The early morning or late afternoon sun is fine, or use a pot that can be moved easily. Prepare the ground with nutrient-rich fresh compost as this will encourage leafy growth. Water coriander frequently with a little water. Keep snipping coriander as this will help produce more leafy growth and prevent it from going to seed. If you see any flowers starting to grow just pinch them out.

There is a coriander variety called slow bolt coriander that is good for warmer climates. Use a certified organic variety so that when your coriander does eventually flower, at the end of the season the seeds it drops will grow where they fall (self-seeding). Plants are clever at acclimatising to their environment, so the self-seeded seedlings that pop up next season will be stronger and better suited to your garden.




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