As gardening season shifts into the "maintain and enjoy" phase, I thought it would be helpful to share some info on keeping your plants at their very best through the hot months.
As plants grow bigger and better, one common problem is that soil runs out of some or all of the major nutrients required to sustain flourishing. This is typical for hanging baskets, patio pots and other contained spaces, as well as in ground gardens and even the lawn. Some indications that plants require nourishment include leaf yellowing, sparse growth, leaf drop and also secondary problems such as increased presence of insect or fungal disease. Ideally, plants will receive adequate nutrition before any signs of stress occur - but even after these symptoms show it is easy to correct the problem.
For planters, the easiest way to ensure strong plants is to start with a compost-based soil and then supplement with the appropriate liquid or slow release organic fertilizer through the summer months. Foliage plants require a balanced fertilizer (e.g. 3-1-2), blooming plants require relatively more "P" (middle number; phosphorus), and fruiting vegetable plants require less "N" and the addition of calcium, magnesium and other trace minerals (for healthy fruit development). Both liquid organic and slow release organic spikes are available for all of these plant types.
For in ground gardens and lawns, there are a few special ingredients in the organic gardener's tool kit. These are essentially soil building and balancing products, that also supply major and/or trace minerals. But most importantly they help build the structure of the soil, which has a dramatic impact on the way nature looks after the rest (through increased beneficial microbial activity which yields better nutrient uptake and disease resistance, plus better water management properties). These ingredients will keep plants looking, tasting and producing in top form all summer long.
Some of these may sound familiar, others not so much, so here is an overview of four very helpful organic amendments and what they can do for your lawn and garden. Each has properties that go beyond what regular organic fertilizer or compost can deliver, and each has general application plus special situations for which they are extra beneficial:
Oyster Shell Flour
> Ideal source of slow release calcium, magnesium and several other trace minerals that are vital to healthy fruiting vegetable crops
> Raises soil pH in acidic soils, and is an excellent alternative to lime
> Alternative to bonemeal as a transplant root booster
Application rate: 2.5 lbs (1 kg) per 100 sq. feet
> Corrects iron deficiencies more effectively than most other products
> Source of 30 trace minerals
> Regulates soil moisture release, holding up to twice its weight in water
> Binds sandy soils and loosens clay soils
Application rate: 2.5 - 10 lbs (1 - 4.5 kg) per 100 sq. feet
Glacial Rock Dust
> Remineralizes depleted soils, improving vigour and yield - very popular for vegetable gardens
> Improves soil structure
> Improves soil microbial activity and helps build root system strength
> Improves nutritional quality of home-made composts (especially when combined with alfalfa meal)
Application rate: up to 25 lbs (10 kg) per 100 sq. feet; sprinkle onto soil, or gently work into the soil. May be applied to the garden or containers.
> Excellent non-animal source of nitrogen, as well as potassium
> Greens-up lawns very well
> Enhances microbial activity in lawn and garden settings
> Improves nutritional quality of home-made composts (especially when combined with glacial rock dust)
> Biologically complex blend of minerals, sugars, starches, proteins and amino acids
Application rate: 10 lbs (5 kg) per 100 sq. feet