Soil advice

Michael Mace via pbs
Wed, 21 Oct 2020 21:34:05 PDT
David wrote:

> Any suggestions or recommendations would be greatly appreciated

Welcome, David! As you're already seeing, many of us have advice on soil. I
think we all agree that your soil should have a good balance of water
retention and aeration. There are a number of ways to achieve that goal, and
I don't think I have ever seen conclusive proof that a particular soil
formula is the perfect one. We all have different garden conditions, and
probably what works well in one place wouldn't work somewhere else.

Now that I've hedged a bit, here's what works for me in San Jose, CA.

When I was growing in pots, I used a mix of 50% milled peat and 50% washed
sand (you want sand that is fairly coarse and has the fines removed;
sandblasting sand is good). I added about a tablespoon of complete bulb
fertilizer per 8-inch plastic pot. That was the soil mix recommended by the
old Calochortus Society, and in my conditions it worked extremely well. The
big downside was that the bulbs tended to dive to the bottom of the pots and
then die, so I had to repot every three years or so to rescue them.

I got tired of repotting all of those pots, and switched to raised beds. I
could not get milled peat in bulk, so I switched to a mix of equal parts of
pea gravel, #2 sand, and planting mix (the mix made by the local landscape
supply company). That gets supplemented with complete fertilizer. This mix
has worked nicely so far.

I tried a number of other soil additives. Mixes with redwood compost did not
perform at all well. Pumice was OK but didn't seem to perform better than
anything else, and was hard to get in bulk. Perlite was a bit too light in
my opinion (the soil dried out too quickly). Commercial potting soil was a
good ingredient for the first year, but over a couple of years it broke down
to a black powdery sludge that did not drain well.

The big thing for me was to avoid fines. Anything that included a lot of
powdery material seemed to cause problems, I think because it inhibited air

One other thought: Calochortus species from the Pacific Northwest can be
difficult in California. Some of them want chilling in order to sprout,
others do not appreciate our long drought in summer. I recommend that you
look through the old Calochortus Society newsletter archives on our wiki;
they have a lot of species-specific growing advice that may give you ideas.…

Good luck!

San Jose, CA

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