Weeds in seed pots and elsewhere

pelarg@aol.com pelarg@aol.com
Mon, 16 Nov 2015 18:43:33 PST
Oh there are some persistent weeds that try their best  not to be banished from pots or the ground. I think the worst offender for me in pots is the common yellow Oxalis, O corniculata in its various green and maroon forms.  Odd that a species from a genus I much favor would also be a candidate for worst weed ever.  I fought it in greenhouses when I worked at a bg, and I still fight it outside and in pots that come inside too.  It seems to have two forms, a upright one that is easier to pull and a creeping form that has a taproot and also roots as it creeps.  Often the latter has reddish leaves too.  They become very apparent this time of year as other plants begin to die down or get frosted back, but they are always active and growing except in the dead of winter.  I try very hard to get them out before they seed but it is impossible to get every single one.   The seeds of course fly everywhere and are evidently persistent in the soil.   Glyphosate does not stick very well t
 o the foliage so it is of limited use.   I just have to go and dig them all out as best I can.  Incidentally I have found that a garden tool my sister got for me, I dont know its name but it is a Japanese trowel/knife of some sort, with a narrow very strong blade, wood handle and serrated teeth on one side of the blade, is perfect for weeding and planting.  The sharp tip is good for getting the oxalis right where its tap root is going down, and the blade is deep and strong enough to get out the bigger tap rooted weeds like dandelions and wild lettuce.   The edge can be used to rake over the soil to cut down swaths of emerging weeds as well.   There is some kind of winter cress that we have too, it is looking very happy right now and when it is pulled it smells a bit like arugula.  It also invades pots but gets most robust in the ground.   One way I fight such weeds is to grow flowers that outcompete them, for example I have two color forms of Silene armeria, aka "none so pre
 tty", a winter annual that can seed quite prolifically and its rosettes can give the winter weeds some stiff competition.  Of course then it becomes somewhat of a weed so it needs thinning in spring, but I'd rather have it than the cress and the oxalis.   Onion grass is also coming up now and that requires special attention as the bulbs will regrow so they cannot be composted and are also not easy to kill with glyphosate so it has to be put in the trash.   Each bulb is likely to have a bulblet or two along the sides as well which may not have sprouted so you have to get those too or be ready to come back and dig them when they do sprout.  At least it is relatively easy to get it before it "flowers" (or more accurately makes aerial bulblets) and it stays in place until I can get to it.  But I am tackling what probably was a few decades worth of population increase before we got this property in 2013.  Similar in its refusal to die and therefore needing special disposal is the
  common purple violet which has tough thick rhizomes that resprout no matter how deep they get dug into the ground or how long they remain out of it, plus it is cleistogamous and shoots seeds everywhere.  It will easily outgrow and cover things like crocus or snowdrops.  Fall is also the season for chickweed and a furry leaved chickweed relative too, they are best cut at the root with my handy garden tool.   Grasses were a huge problem in my pots that summer outside until I got rid of the back lawn and made it all garden (only part of the front lawn is left and its days are numbered) and in so doing got rid of the lawn mower folks who blew the seeds of grasses and other weeds all over after mowing the grass and weed wacking the patios.  I worked hard with glyposate and by hand to get rid of weeds in between the bricks or slate of the back patios and right now have more self sown flowers (Silene armeria, larkspurs, Ursinia nana, Helichrysum sp and Cotula sp, and even delosper
 mas) coming up in those areas than weeds, which I actually like.   
A special situation occurs with the potted winter growers when I set seed on them and some of the seeds get into other pots before I catch them. This occurs most often if I cross different clones of Oxalis obtusa, the seeds will come up the next season in other pots as they also fly far.  In summer Ledebouria zebrina sets copious seeds which sprout immediately in neighboring pots but they dont get too far from the parent plants at least.  I also purposely sow another geophyte, Bonatea speciosa, from seeds I set on existing plants, into neighboring pots, that is the only way I can get seedlings so far.  Event though I can and do grow orchid seeds on agar media, I have not yet found a good one for the Bonatea, yet it will come up in pots that aren't disturbed.  The small plants can then be removed and potted up singly to grow on once they have a decent sized tuber.  
Ernie DeMarie
Still planting discounted dutch bulbs while the weather remains warmer than normal in NY

-----Original Message-----
From: Jane McGary <janemcgary@earthlink.net>
To: Pacific Bulb Society <pbs@lists.ibiblio.org>
Sent: Mon, Nov 16, 2015 7:25 pm
Subject: [pbs] Weeds in seed pots

On 11/16/2015 9:33 AM, Michael Mace wrote:
> PS: The rainy season arrived
here two weekends ago. For those of you 
> who don't live in a Mediterranean
climate, this is our equivalent of 
> spring -- you can almost feel the land
starting to wake up after the 
> long summer drought. Amaryllid seeds are
ripening, the hills start to 
> turn green, and I rush through the last bits of
bulb planting that I 
> didn't finish in the dry season. Little green sprouts
are starting to 
> appear in many pots. Two thirds are weeds, one third are
bulbs. But 
> which are which? When in doubt, I leave them -- but that means
> weeds later, and I'll never have the time to pull them all. So I'll 
call them "indicator plants," and promise myself that next summer I'll 
change out the potting mix. PPS: It turns out that putting window 
> screening
around a raised bed doesn't keep out all weed seeds. Darn.

The nice thing
about growing bulbs from seed is that most of them are 
monocots, so any dicot
that comes up is a weed. I leave most of those 
until they make a pair of true
leaves, which are easier to get hold of 
and pull. If you're growing dicots,
the true leaves generally betray the 
identity of the weeds better than the
cotyledons would. The only monocot 
weeds likely to come up in seed pots are
grasses, and they're pretty 
easy to distinguish from the bulbs because they
quickly develop a second 
leaf; also they have a different surface texture, if
you have sensitive 

It's awful how weed seeds blow around. I keep
my seed pots in a 
three-sided, glass-roofed shed, and still cress and
Epilobium seeds blow 
into them.

Jane McGary
Portland, Oregon,

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