Encouraging Calochortus to Set Seed

Jane McGary janemcgary@earthlink.net
Sat, 17 Aug 2013 11:00:39 PDT
Chris asked,
>Jane, thanks for the suggestions. I can rework the mix.  Can I pick 
>your brain further:
>1. Any commercial products you like that qualify as loam? That 
>ingredient always stumps me and the native soil here ain't nowhere 
>close to loam.

If you go to a garden center that offers a wide range of soil mixes 
(the one nearby serves "indoor gardeners," wink wink), look through 
the ingredients for something like "leafmold" or "forest humus." Some 
municipalities compost leaves and/or garden debris and sell it, too. 
I formerly dug and sieved topsoil from a forest on my country 
property, but now that I live in the city I've been composting oak 
leaves and buying suitable bagged mixes or products by the yard from 
nursery suppliers. Some of the latter will load more than one 
ingredient in the truck, and you can mix it after it's delivered. 
Some will even pre-mix it if you order enough.

>2. How do you feel about Perlite as an ingredient in this situation? 
>Asking because I came into a big pile of it.

I would NEVER put Perlite into a garden bed. It has no nutritional 
value and does not hold water, and it floats to the surface and blows 
around. Its only value is its light weight and slow breakdown, which 
makes it useful for container growing where the mix is irrigated 
almost daily and fertilized heavily, and the flats or pots have to be 
moved around a lot manually. If you can't get pumice, which you 
probably can't in quantity, I suggest using a small size of sharp, 
washed crushed rock, often known as "quarter-ten." Do not use 
"quarter minus" unless you wash out the fines first.

>3. The sand I can most easily get is playground sand. I assume I 
>need to rinse it in case it is full of salt?

I don't know what to do about seashore sand, can someone else help? 
"Playground sand" might be too fine and rounded, anyway. Even here 
around Portland, Oregon, I don't use the local sand derived from 
valley river deposits because it's too rounded and silty. Instead, I 
had several truckloads of sand from an upriver quarry brought in -- 
expensive transport, but well worth it.

>4. Btw, I actually think the area's decomposed granite may also be a 
>good primary ingredient for this purpose because it contains 
>everything from fines to grit to irregular pea-sized bits and 
>retains more moisture than I expected before I tested it.

I'm familiar with decomposed granite because it's the type of soil in 
my brother's garden in the California Coast Range. It is used for 
paths and other compacted applications because it hardens into an 
almost impervious surface when dry. Once wet, however, it opens up 
some unless it's been mechanically compacted. There are bulbs that 
grow in it naturally. When my brother and I added a compost plus 
sandy loam product from a nearby landscape supply company to the 
moistened decomp granite (it was my birthday present to him), we 
ended up with a pretty good planting bed in which a number of bulbs 
are flourishing.

The other day I visited a friend's nursery and saw some 
healthy-looking bulbs being grown in a mixture of pumice and very 
well composted cow manure. The only thing I found wrong with it was 
that it seemed to get too dry, especially in the smaller sizes of 
pots exposed to heat. Another nursery where alpines and some bulbs 
are grown uses a lot of quarter-ten in mixes, troughs, and display 
beds; fortunately one of the proprietors is big and strong!

A good chapter on soil ingredients appears in the Timber Press book 
"Rock Garden Design and Construction," which is out of print but 
widely obtainable. Most books on rock and alpine gardening discuss 
this topic at some length, but some of them, especially the older 
ones, go overboard on insisting on special mixtures for different 
kinds of plants. Most of us these days use just two or three formulae 
for all our plants.

I hope this helps Chris and doesn't bore everybody else too much.
Jane McGary
Portland, Oregon, USA

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