|This article comes courtesy of NZ gardening writer Wally Richards,.
Phacelia tanacetifolia has been in the news over the last few years as the spring flower which feeds hoverflies and other insect predators, getting them going early in the season on the job of eating up aphids and other pest insects. Experiments at Lincoln University found phacelia -- there doesn't seem to be a common name, apart from bee flower -- planted round the margins of organically grown crops and in strips through the crop -- seemed to give some reduction in pest insect damage.
Hydrophyllaceae family members, hardy annuals, first introduced to Britain from the New World last century, they can thrive in sun or shade, rich or poor conditions -- though obviously better in fertile soil -- and are undemanding. All are summer-flowering, either early or late. Species cultivated include campanularia, blue, 20cm, California; congesta, blue or lavendar, 60cm to 1m, Texas and New Mexico; parryi, violet, 30cm, California; tanacetifolia, blue, 60cm to 1m, California; viscida, blue and white, 45cm to 60cm, California; whitlavia, (Californian bluebell), early autumn, 30cm, California.
Though phacelia attracts hoverflies, bumblebees and honey bees, they are not attractive to wasps.
As the organic advocates have been saying for years, organic methods have to be persevered with for a couple of years before the benefits begin to be seen. Whether in horticulture or agriculture, the system has to bed itself down before the pests and diseases begin to diminish.
Summer unfortunately brings with it a host of uninvited guests in the garden, such as weeds and plant pest insects. Both are willing to work hard to take over the place, and unfortunately the gardener may have to work equally hard to prevent this happening.
Gardeners who potter about in the garden frequently are better off than those who tackle the whole garden with a burst of energy once a month or so, neglecting it the rest of the time.
This particularly applies to weeds, though continuous work is needed on pest insects -- and diseases -- too.
Have you ever noticed how much easier it is to pull out weeds after rain? They come out easily. Now there is a hint. Put the sprinkler on the small area you plan to clear of weeds before you tackle it.
Unfortunately rain -- or irrigation -- plays havoc with gardeners who like to rely on the hoe to kill weeds. Hoeing wet soil will merely shift the weeds around from one place to another. Something else may be needed.
A jug of boiling water poured on the foliage can help kill unwanted weeds while another organic method is a strong solution of liquid fertiliser made with sheep or poultry manure, or even a strong solution of blood and bone. Strain carefully to keep out pieces which could block the nozzle. This strong mix will kill any foliage it is sprayed on without harming the soil or adjacent plants.
Unfortunately some weeds with strong underground root systems, like oxalis, cannot be controlled by simple means and need a lot of effort.
But cheap and simple -- and organically approved -- ways of controlling some pest insects can be adopted. For instance, a strong jet of water will blast spittle bugs off foliage, or aphids off rose buds, without harming either the gardener or the environment. And granny's method of throwing soapy water over them is still a sovereign remedy.
Slugs and snails are usually less troublesome when the weather becomes warmer and drier, but a shower soon brings them out again to attack young plants, especially at night.
There is another hint. If moisture brings them out, then irrigate heavily the areas where they normally lurk to draw them out. These include the base of a hedge, an ivy covered wall or fence, round compost heaps and quite often in some forms of ground cover. Once stirred into activity with the moisture of irrigation or a heavy shower, the traditional saucer or tin lid of beer to attract and drown them will cut down their numbers safely.