Seasonal Gardening: Cacti and Succulents, Controlling Greenhouse Whiteflies and Soil Disease

The Seasons of the Garden column shares seasonal gardening news briefs on amending cacti and succulents, controlling greenhouse whiteflies and controlling soil disease.


| November/December 1986



102-020-01a

British expert Roy Mottram says that although people associate succulents with harsh alkaline soils, their soil pH should be slightly acidic-ideally, 5.5.


ILLUSTRATION: MOTHER EARTH NEWS STAFF

The Seasons of the Garden column shares seasonal gardening information and tips with MOTHER EARTH NEWS readers. 

Seasonal Gardening Research Briefs

Suffering succulents! If your indoor cacti and other succulents suffered from neglect during the gardening season, now's the time to make amends. British expert Roy Mottram says that although people associate succulents with harsh alkaline soils, their soil pH should be slightly acidic-ideally, 5.5. So check your tap water for alkalinity if your plants seem unhealthy. Mottram also recommends giving succulents weak doses (1:1:2) of N-P-K fertilizer and adding organic matter or sterile soil for trace elements.

Succulents can tolerate fairly high levels of soluble salts-if the pH isn't too high but extreme salinity kills roots. So water occasionally but thoroughly to wash out accumulated salts, and repot any plants that seem to be either waterlogged or difficult to wet; they're most likely full. of salts.

Control greenhouse whiteflies. Yellow sticky boards control greenhouse whiteflies (EDITOR'S NOTE: See "Getting the Most From Your Solar Greenhouse" on page 74 of MOTHER EARTH NEWS NO. 102), but according to Japanese horticulturists, their effective range is only one yard. So space them no farther than three feet from plants and from each other. Their efficiency also drops sharply when daily highs are under 80 degrees Fahrenheit.

Beware metallic blight! Some landscapers and homeowners don't remove the soilballing wire mesh from trees and shrubs when transplanting, because they think the wire will break down quickly in the soil. Not so! Dr. James Feucht of the Colorado Extension Service found that mesh buried for 15 years can restrict root growth and even kill formerly healthy plants especially during a drought. (The size of the mesh openings doesn't matter.) The moral? Remove wire from root balls when planting.

More on controlling soil disease. In our May/June column, we reported on soil amendments developed in Taiwan to control soil-borne disease. Plant pathologists in Hawaii now claim they controlled damping off of cucumber seedlings (caused by the Pythium splendens fungus) by adding 0.6 % calcium and 1 % alfalfa meal, by weight, to infested soil. (Calcium carbonate, hydroxide, and sulfate were all used — the last does not increase pH.) Perhaps a bit of calcium and organic matter can provide good insurance against many soil-borne plant diseases.





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