Grant Douglas's Garden Diary

Week 20: Third week of May

With all the rain we have had lately, those of you on heavy soils will be finding it difficult to do any work or keep your plants growing rapidly. The rain not only makes the ground wet but drops its temperature as well. There are a couple of things you can do (apart from such things as raised beds) to improve your soil structure.

Clay soils are made up of extremely fine particles with very little gaps between them which prevent moisture, air and root penetration. By encouraging the clumping together of these fine particles to make a "crumb structure", we can encourage all these things to happen. The addition of organic material such as compost, manures, raw organic material, provides humus which sticks the fine particles together and forms crumbs, but you can also achieve the same results using lime or gypsum.

Both of these materials are calcium-based but unlike lime, gypsum does not change the pH of your soil. The pH of your soil is the level of acidity of the soil. The average pH for a vegetable garden is 6.5 which is slightly on the acid side so if you have an average soil that your are successfully growing things in, by applying lime you may make the soil too alkaline and thus prevent good growth.

If things are growing well in your garden and you are not applying strongly acidic fertilisers (most artificial fertilisers), but applying compost and manures (although chook manure can be a bit acidic in large quantities) then their should be no need to apply regular doses of lime as most conventional gardening books recommend. So there are great advantages in using gypsum to condition your soil, as it doesn't change the pH. Gypsum is a naturally occuring mineral (calcium sulphate), that can be broadcast over the surface and allowed to wash in, so now is a good time to do it, with all the rain occuring.

Not only will gypsum improve your soil structure but will also supply essential calcium which is needed in reasonably large quantities by plants and sulphur which is still essential but required in lesser amounts. Application rates to improve clay is 1-3 kgs per square metre and as a general dressing on your vege garden to both feed and improve soil structure is 0.5 - 1kg per sq.m.

Now is the time to be thinking about preparation of new beds for Strawvberries, Asparagus, and Dividing Rhubarb - more about bed-preparation in another diary.

Red Onions can be sown from now on. Choose slow-bolting varieties to start with e.g. Rambo (available from Egmont Seed)

If you are in colder areas, most things you plant now will sit for much of the Winter if you can't offer them some form of protection, so you may want to hold off planting for the next 6 - 8 weeks.

Sowing or Planting this week: (may need some protection til germination takes place)
Brassicas - Cauli, Cabbage, Broccoli, Broccoflower, Brocoflower (remember to choose Spring varieties of these brassicas eg Wintercross or Flower of Spring Cabbage, Snowmarch Cauliflower)
Garlic
Lettuce (Loose-leaf Fancy and Triumph Hearting)
Perpetual Spinach (Plants only)
Red Onions
Shallots
Silverbeet (Plants only)
Spinach (winter varieties eg. Hybrid No.7)
Spring Onions

Sow Direct: (may need some protection til germination takes place)
Chinese Cabbage and other Chinese Greens Corn Salad
Mescalin Mix
Radish
Rocket

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