Tuesday, February 21, 2017

Organic Weed Control Class Notes

When Ben Franklin said, “Nothing is certain except for death and taxes,” he revealed that he was not a gardener. Gardeners know that weeds should be added to that list.

Sadly, there is no magic bullet.  There is not a product alive that does what Roundup promises.  Not even Roundup does what Roundup promises.  So, unless you want to pave your entire yard, you will have to deal with weeds. 

First, Know Thy Enemy:  what kind of weed are you dealing with?  This will dictate how you will control them. 

Types of weeds:
v  Annuals ~ Weeds that complete their entire life cycle in one season. Easiest to get rid of physically, but quickest to reseed.  Examples: Cleavers, Chickweed, Henbit, Hedge Parsley (Torilis), Annual bluegrass,
v  Biennials ~ Plants that complete their life cycle in two years. Easier than perennials to get rid of, but harder than annuals. Examples: Wild carrot and it's incredibly toxic lookalike Poison Hemlock.  (Note: LEARN about poison hemlock, then always use gloves when eradicating it. It really IS as toxic as they say.)
v  Perennials ~ Weeds that live for years, going dormant in winter (usually) and sprouting again to grow in spring/summer/fall.  This includes many types including creeping, rhizomatous, and bulbous.  Examples: Bermuda grass, Nut grass (Nutsedge), Sheep Sorrel, Johnson grass, Dallisgrass, and Crabgrass.


Basic ways to control weeds:
v  Annuals ~ Cut them off at ground level or just below the soil surface.  Don’t let them go to seed.
v  Biennials ~ Same as annual control when they’re young, more like perennial control when they’re older.
v  Perennials ~ Dig them out, sheet mulch, repeated vinegar/orange oil sprayings, repeated pruning to ground.
Some Tips
v  First, avoid weeds.  One year of seeds means seven years of weeds, so don’t let any go to seed if they get away from you. 
v  Don’t put those that have gone to seed in the compost pile or they will come back to haunt you.
v  Increasing soil fertility and organic matter content discourages many weeds. 
v  Damp soil is easier to pull weeds from.  Not wet – you never want to work wet soil as it can cause clods that take forever to “melt”.  And not dry – dry soil can be rock hard, and harder to pull weed roots from. 

Ways to control weeds:
About weed barrier fabric – I’m not a big fan.  It stops natural cycles (leaves falling on soil and breaking down, and soil moisture level fluctuations) and many times don’t work anyway, leaving a mess of plastic threads you have to pull up (which isn’t always easy if Bermuda has clambered across it and pinned it to the ground).  If you do use it, try to use a thick paper one so it will eventually break down and not leave you with that mess to clean up.  In extreme circumstances, when sheet mulching hasn’t worked, use heavy black contractor’s plastic covered with mulch, then pull up in a year or two. 

In the lawn:
v  Keep the grass as healthy as you can so it can choke out most weeds (Refer to our Organic Lawn Care Guide).  Also, increasing soil fertility and organic matter content discourages many weeds while encouraging turf grass. 
v  Corn gluten – A pre-emergent weed killer used at least twice a year just before the two main weed-sprouting times: at the change of cool weather to warm weather and warm back to cool. (Refer to our Corn Gluten handout)
v  Hand digging/hand removal – There are a number of hand tools that will help you with this.  Check into Cobra tool, hori hori knife, Cape Cod weeder, rockery trowel, radius weeder, ball weeder, cork screw weeding tool, daisy grubber, Ho-Mi (Korean EZ-Digger). You can also use a knife or screwdriver for some things, and a regular dinner fork and/or longer-handled barbecue fork.
v  Weed popper for clumping weeds and those with large taproot systems.
v  In extreme cases, use a spading fork to loosen the area in and around the weeds, pull them up roots and all, then carefully replace the grass.  Care will need to be taken for the grass after this as you’ve effectively just transplanted it.  Seaweed and extra watering will be needed.

In planted beds:
v  Mulching – A good, thick layer of mulch will shade out most weed seeds and make any others easier to pull since they won’t be as well-rooted.
v  Hoes – stirrup hoe (aka oscillating hoe) is my favorite.
v  20% Vinegar – This extra-strong vinegar can be sprayed as is, or mixed with orange oil and soap (See the Poison Ivy Killer recipe on NaturalGardenerAustin.com). 
v  In extreme cases, use a spading fork to loosen the area in and around the weeds, pull them up roots and all, then carefully replace the grass.  Care will need to be taken to avoid roots of established plants if possible.  If not, seaweed will help them get over it.

In veggie beds:
v  Intensive planting – Planting crops so close together that they act as a living mulch.
v  No-Till, or minimizing soil disturbance – Some weed seeds can lay dormant for decades and only need the briefest light exposure to germinate, so tilling actually increases weed seed germination.  It’s best to avoid if you can. 
v  Cover cropping – Cover crops shade out the newly sprouted weeds and add organic matter to the soil, increasing its organic matter content and nitrogen content (when using legumes as a cover crop), discouraging weeds in the process.  Cool season cover crops good for our area are crimson clover, Australian winter pea, elbon rye, perennial rye, and annual rye.  Warm season cover crops are buckwheat and cowpeas (black eyed peas, purple hull peas, cream peas). 
v  In extreme cases, use a spading fork to loosen the area in and around the weeds, pull them up roots and all, then carefully replace the grass.  Care will need to be taken to avoid roots of established plants if possible.  If not, seaweed will help them get over it.

In new areas that will be planted beds or veggie beds or lawn:
v  Sheet mulching – Multiple layers of compost-newspaper-cardboard to shade out and rot weeds below.  It must be left in place for at least two seasons before planting through it, longer for certain hard-to-kill weeds.
v  Pre-Sprouting – Watering the area to encourage weed seeds to sprout, then tilling again or using a hoe to kill them while they’re still small.  You can do this for a month, hoeing once or more a week, and you will presprout and kill 90% of the weed seeds. 


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