potting mix question

Brian Whyer brian.whyer@btinternet.com
Sun, 28 Dec 2008 03:16:23 PST
> I have a lot of young Glads, Moraea, Babiana etc. that will need to be
potted up this
> next summer in their next dormant period. I know everyone has their
> potting mix, though my question is one of layers.
> I was wondering if anyone can tell me if there is any advantage to using
the potting
> mix only in the lower part of the container. Then placing the bulbs on the
top of the
> potting mix and use some small gravel ( or like material ) to cover the
bulbs to their
> appropriate depth.

This technique certainly works for me, here in England, for juno irises,
with the thongy roots in compost, but the bulbs, and several inches above
course gravel. I can leave a large long-tom pot (height 1.5-2 x diameter)
outside in all weathers, all year round, with minimal losses. Something I
cannot do if the compost fills the pot, where I would have to use much more
effort even under glass, getting the moisture content thoughout the year
right to prevent rotting, or desiccation. It can also help to inspect some
other types of bulbs during dormancy as you can pour the gravel off and
there they are.
But with smaller pots you have to remember if the bulbs are planted ~half
the depth of the pot, then removing the top half of the compost, leaves less
than half (in a tapered pot) the nutrients, and possibly ion exchange
material remaining, so you will have to liquid feed much more often. Over
potting in a larger than normal pot or standing on an absorbent sand base
reservoir may help alleviate this a little though.

Brian Whyer, Buckinghamshire, England, +3C max, -3C min today

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