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Tuesday, April 5, 2022

Diatomaceous Earth, An Organic Insecticide




Diatomaceous earth (DE) is an inert dust mined from the remains of fossilized silica shells of certain algae known as diatoms. It is composed of approximately 3% magnesium, 33% silicon, 19% calcium, 5% sodium, 2% iron as well as other trace minerals such as titanium, boron, manganese, copper and zirconium.

DE works in two ways to kill an insect. 1) It absorbs water-protecting fats and oils from the outer, waxy layer on the surface of the insect and causes desiccation, or dehydration.  2) Being highly abrasive, DE scrapes and cuts the insect’s cuticle layer, contributing to more desiccation. However, it is virtually nontoxic to mammals.

Around the home, dusting the powder on the floor, carpets and crevices will kill cockroaches, silverfish, ants, and fleas.  Since the powder must stay dry in order to be effective, repeat applications may be necessary in humid areas; DE will be more effective in drier climates. It is also used to control beetles where grains are stored.

The same basic principles used to kill indoor insects can be applied to insects which attack plants outdoors. Some gardeners will dust plants with diatomaceous earth in order to kill insects such as aphids and beetles which feed on the plants. DE is moderately effective against slugs and snails as long as the material remains dry. The problem with outdoor use is high humidity and rainfall. When DE becomes wet, its effectiveness is diminished. DE, however, can be mixed with water as its carrier and applied to such targets as ant nests. When DE dries out naturally, it will begin to take effect. Nonetheless dusting plants with DE is the most effective application method. The dust can cause eye irritation so wearing goggles and a dust mask is recommended. 

Insecticidal DE is not the same as the DE used in swimming pool filters. Other chemicals are added to pool grade DE, and the product is heat treated. This causes it to assume a crystalline form and is a respiratory hazard. Pool grade DE should never be used for pest control.

Wednesday, January 5, 2022

Edible Landscape




Since the early 1900’s Americans began the great migration to the cities, and in doing so gave up their foraging practices. In earlier times people often searched their property and nearby fields and hills for edible food. In some parts of the world this is still a common practice. 

The time has come to begin foraging within our ornamental gardens and see what nutritional edibles can be gleamed. Caution: Proper investigation is necessary to verify that the chosen plants are safe to eat.  Consuming the wrong plant can be disastrous.

Here is a short list of some well-known edibles in the United States. Check the internet, especially university websites for a more comprehensive list.

A. Weeds - If you can’t beat them, eat them!
1. Dandelions, Taraxacum officinale -Fresh dandelion leaves can be eaten raw, in salads, added to a stir fry, or boiled and steamed like spinach. They have a bitter taste, but boiling will help take that out. Dandelions also make a great addition to soups and stew. They are high in carotenes, iron, calcium and vitamins A and C. As a detoxifying agent, dandelions aid with liver, urinary and gall bladder disorders, diabetes and high blood pressure. Dandelion root tea is sold in local health food stores. 
2. Lamb’s quarters (Chenopodium album) is also called wild spinach with similar nutritional value to spinach. 
3. Burdock (Arctium Lappa) is a weed rich in potassium, iron and calcium. 
4. Common mallow (malva neglecta) the leaves, stems, and immature seeds are eaten raw or cooked. Mallow is reported to be rich in calcium, magnesium, potassium, iron, selenium, and vitamins A and C.
5. Purslane (Portulaca oleracea) is a succulent; the leaves, stems and flowers can be eaten either fresh or cooked. The leaves contain more omega-3 fatty acids than any other leafy vegetable plant.
Other edible weeds include chickweed, white and red clovers and plantain.

B. Edible Flowers
1. Marigolds are one of the most commonly grown ornamental annuals. When dried and crumbled, the petals of marigolds can substitute for the most expensive spice in the world: saffron. 
2. Roses, both the petals and the rosehips (fruit), are edible. Rose water is often used in scones, cakes, sherbets, salads and icings.  
3. Sunflowers – in addition to the commonly eaten seeds, the petals can be added to soups and stir-fry dishes. The sunflower buds can be steamed and eaten like an artichoke.
4. Daylilies (Hemerocallis sp.) - Some species (especially H. fulva) are cultivated in Asia for their edible flowers. The petals can be eaten raw or more commonly dried and used as a flavoring in soups. The young shoots should be cooked and have a pleasant sweet flavor. Even the roots are edible.
5. Nasturtium, violas, borage and calendula flowers are also edible and frequently used in salads.  

Here is a final thought: some vegetables can be planted as ornamentals in landscape gardening. As shown above, swiss chard with the bright red stems and large leaves of cabbage add a delicious touch to the surroundings.

Photo: University of California Master Gardeners of Sacramento County

Friday, September 24, 2021

Gardening Tips for Beginners


Starting a vegetable garden? 

Here are some fundamental points to help cultivate success:
·        Gardeners need only as large a garden as they can easily maintain. Novices often give up gardening because they plant too much and find themselves overwhelmed with many of the garden chores: planting, weeding, pest control, soil preparation. 

·        For some people, it’s a good idea to plan the garden on paper before tilling the earth. 

·        For those with minimal space, grow crops that produce the maximum amount of food for the area.  Radishes, onions, lettuce, bok choy and tomatoes usually produce abundantly in a small space. On the other hand, plants like pineapple, watermelon and pumpkin squash require more room.

·        Gardeners need to choose recommended varieties for their area. The University of Hawaii CTAHR seed program,  http://www.ctahr.hawaii.edu/seed/, develops and sells vegetable seeds suitable for the Hawaiian Islands; in Hawaii, begin with these varieties. For other areas in the United States, the local University Extension Service will have recommended varieties.

·        The best garden sites should receive at least 8 hours of full sun each day; in other words, vegetables will not grow as well if shaded by trees, walls or fences. Nearby trees and shrubs, with roots reaching into the vegetable patch will also compete for water and nutrients.

·        Level ground is easier to manage, but if the land is sloping, the rows need to be planted across the slope, not up and down.  This will help keep the soil from washing away during heavy rains.

·         A garden that is located within easy walking distance to the house is convenient for carrying tools and eventually returning with baskets of produce. 

·        For those with smaller gardens, growing crops vertically will take less space than those grown horizontally. Vining crops such as tomatoes, squash, cucumbers and pole beans can be trellised or staked to maximize space and increase garden productivity. Wooden structures, stakes, twine, wire cages or nearby wire fences are useful supports.

·        Perennial vegetables such as rhubarb and asparagus need to be planted to one side of the garden so they are not disturbed as the ground is prepared for subsequent annual crop. 

·        Tall crops such as corn should be planted on the north side so they don’t shade low growing vegetables.

·        And finally, succession planting is a good gardener’s method to assure continual harvest. A crop like tomatoes can be harvested over a long period of time. Therefore one planting will last for many months. However, with other crops like corn, beets, lettuce and turnips, the entire crop will mature at approximately the same time. With a crop like corn, staggering the plantings at one to two week intervals will enable harvesting ears over a longer period of time.

An additional note: because corn is wind pollinated, it should be densely planted in order to achieve good pollination.  Planting just a few corn plants will likely result in ears that lack a full complement of kernels which is a sign of a lack of pollination.  Plantings of a minimum of 3-4 short rows will be pollinated more successfully than 1 or 2 long rows. It is best to plant 3-4 rows, about 8 feet long.