Posted on by tonytomeo · 2 Comments

Blue or Pink

As a native of the Santa Clara Valley, I am still impressed by blue feral hydrangeas.

Hydrangeas were so much more predictable only a few decades ago. They were either colored or white. White was obviously white. In the Santa Clara Valley, colored was pink. We knew them as colored only because they technically had potential to be blue, whether or not we actually saw it. Application of aluminum sulfate was necessary for blue floral color. Such color was only temporary, and could fade in the process of bloom if the dosage of aluminum sulfate was inadequate. Consequently, blue hydrangeas were rare. However, within the redwood forests of the Santa Cruz Mountains to the south and west of the Santa Clara Valley, most colored hydrangeas were blue. Application of lime was necessary to make them pink. Just like blue floral color within the Santa Clara Valley, pink floral color within the redwood forests was only temporary, and could fade in the process of bloom if the dosage of lime was inadequate. Nowadays modern hydrangeas are not so sensitive to soil pH. Blue hydrangeas bloom a bit more purplish in the Santa Clara Valley, but are still mostly blue. Pink hydrangeas likewise bloom a bit more purplish in the Santa Cruz Mountains, but are still mostly pink.

Posted on by tonytomeo

pH Has Ups And Downs

80711thumbEnvironment is what determines what plants grow where. It may sound simple enough, but environment is a combination of many different factors, including but not limited to climate, soil quality and exposure. Each of these factors is a complicated combination of other factors. For example, climate includes temperature, humidity, rainfall, frost dates, winter chill duration, wind and so on.

Home gardening, like the production of horticultural and agricultural commodities, is obviously limited by environment. Plants that want rich soil with good moisture retention are not happy in clay or inert sandy soils. Annual vegetable and flower plants that do not tolerate frost are grown after the last frost, and finish before the first frost. Annual plants that survive frost are grown in between.

Environmental modifications, such as irrigation, fertilizers and other soil amendments, make it possible to grow what would not normally grow in particular environments. However, environmental modifications are not always practical. For example, if the cost of irrigation of a particular commodity might exceed the projected revenue of that crop, an alternative crop must be grown instead.

pH (the ‘power of hydrogen’) is another one of the many limiting environmental factors. It is what makes the soil acidic or alkaline. Some plants prefer the soil to be slightly acidic with low pH. Some are more tolerant of slight alkalinity with high pH. What we choose to grow in our gardens should be adaptable to the pH of the endemic soil, whether it is acidic, alkaline or close to neutral.

There are all sorts of fertilizers and soil amendments that can modify the pH somewhat if necessary. Such amendments make it possible to grow rhododendrons and azaleas and other plants that prefer slightly acidic soil where the soil is naturally slightly alkaline. The problem is that the adjustments of pH are not permanent, so must be maintained. In many situation, major modification of pH is impractical. It is generally more practical to select plants that will be happy with the natural endemic pH.