watering and testing for dryness in pumice

Jane McGary janemcgary@earthlink.net
Sun, 01 Dec 2013 11:41:21 PST
Gastil wrote,
>Ina asked how to tell how dry a pot is which contains a lot of pumice.
>For some pots, I weigh them at the time I pot them ...  I have one 
>of those prong things but it only measures the most
>extreme dry and soggy. This is a good question. I am curious what others do.

Well, I stick my finger into the soil. If it's a plastic pot, which I 
use for seedlings, I can lift it to feel the weight.

In regard to pumice, if it is light-colored like that I use, it turns 
a darker gray when it is holding moisture. This is also true of tufa.

It works best to use your own potting soil, whatever that may be, 
rather than keeping purchased container plants in what the nursery 
uses. Some nurseries use a very non-retentive mix so that the plants 
can be watered daily, or nearly so, by untrained employees or 
automatic systems. I've learned the hard way, and unless I know that 
the nursery's soil is similar to mine, I shake off as much of the 
original soil as I can and repot the plant in my preferred mix if I 
need to keep it for some time before it's ready to go into the 
garden. We home gardeners can afford to use more expensive 
ingredients, such as pumice; and we don't have to lift the flats 
constantly, so we can include heavier ingredients such as grit.

Jane McGary
Portland, Oregon, USA

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