This post, about trying to garden with wainaku in the garden, was written back in November – here it is already February. At the end I will give an update of how the weed suppression experiment is coming along.

“What Happened to the Garden?!”

Yesterday I was working in the garden when a friend walked up to visit.  She had worked with us in the garden a few times last spring.  As we chatted she looked past me into the beds and said in alarm,  “What happened to the garden?!”  I looked to see what she was seeing.   She saw beds piled with brown leaves. “It’s doing great!” I said, not quite getting it.  Then I realized that she was used to seeing beds of lush green kale and other greens.  It  must have looked partly dead.  “We’re in a bed preparation phase.  It’s fall, so the kale has died down. Everything is full of wonderful mulch,” I explained.

A well-mulched garden, full of potential.  We are way behind in our fall plantings but at least we are establishing healthy soil and have the advantage in the weed war!

To me, it looks fantastic, because it is finally under control, and because i know that underneath that mulch is a thriving community of fungi and bacteria and other microorganisms that are breaking down the mulch and turning it into plant food.

Over the last two months the garden committee, which is me and Dave (community garden concept has crumpled due to various factors – future topic), has been laying cardboard in all the paths, and heavily mulching the beds and paths with the available organic matter.  I have a new set of eyes for mulch.  I see mulch where before I saw dead leaves needing trimming or a tangle of weeds.  Now I suddenly see all this abundant tropical growth as mulch, especially when near the garden for easy chopping and hauling.  The mulch material we have been collecting is:

  • bamboo leaves (a basic Natural Farming medium, great for promoting a mixture of fungal and bacterial growth)
  • rotting bamboo stems
  • albezia leaves (N fixer)
  • ice cream bean leaves (N fixer)
  • coconut fronds – leaves stripped off main stem
  • banana leaves and flowers (potassium)
  • rotting banana stems (potassium)
  • ginger leaves – stripped off main stem otherwise they will propagate

We also happen to have a lot of cardboard because we have been building a house and hanging out at places such as Home Depot and Sears’ appliance pick-up area, where we can pick up large amounts of flat cardboard.  A truly successful town trip to me is a day we get whatever errands checked off our lists AND we a pick-up load of cardboard.

Over the bed itself is mainly bamboo leaf mulch, with larger banana and ginger leaves in the path.  We have planted this bed with taro, ginger, beans, and recently lemongrass that will be a personal mulch provider for the bed.

For the paths, first we weed, then lay down overlapping cardboard. We take off the tape and staples and lay flat sheets so that they overlap at least 2 or better, 3 times.  When this is done to create new garden space, it’s called sheet mulching and there’s more to the technique – Here’s a good article on sheet mulching written by Agroforestry Net:

For the beds, after weeding I have been putting down chicken and rabbit manure that has been mixed with biochar, then the mulch.  I have also inoculated some of the biochar with IMO 2, which is a liquid concentrate of beneficial microorganisms grown off of bamboo mulch laid on a bed of rice and sugar .

Panic Rampant!

The instigator of this garden overhaul has, as usual, been the need to control the wainaku grass. I just looked  up wainaku to give you the Latin name – it is Panicum repens – and see that in England it is called Creeping panic, and in France, Panic rampant – I laughed out loud!  The perfect name for our experience with it.   It is also called “Torpedo grass” because of its industrial-strength rhizome’s ability to spear  through weedmat, cardboard, huge piles of blue rock, or anything other than roofing tin (a comment heard at a recent Natural Farming workshop).  It stays alive under heaps of compost in what is supposed to be a weed-smothering blackout phase.  Roto-tilling is its friend, as it will grow from a tiny bit of chopped up root.

Initially it was not in the garden beds, but crept in as fragments in what we thought was compost and got out of control.  Because the gardening occupants here have been sporadic, there has over the last several years been been a cycle that goes as follows.

Wainaku Life Cycle

1- Bed is out of control with wainaku and other weeds; we do an all-out weeding, laboriously digging out the long white roots, which may be three feet down.  If this is a group effort, some do a more scrupulous job than others, and scowl when they hear the “snap” from the less-scrupulous weeder pulling and breaking the wainaku rather than digging down to the crown.  Because it is a large garden, we also invariably have some experimental areas, wherein we conspire to convince each other we can smother the wainaku rather than dig it out.

2- We then may cover the weeded beds with weedmat for several months.

3 – We take off the weedmat, add amendments such as compost (with weed seeds), biochar, blue rock, cinder, IMO’s and manure.

4 – We plant.

5 – The first gardener moves on to other things in life and the weeds move in, including wainaku which was never fully killed.

6 – Remaining gardener roto-tills because he does not have the time or patience to hand-weed it all yet again.  Or, she tries to get community together on an all-out wainaku digging campaign.

7 – The wainaku takes over again because roto-tilling or incomplete weeding just encourages it.

8 – Back to #1… The cycle starts over.

The approach we are taking now is not that different, but we are doing a much better job of having mulch on hand BEFORE we weed any area, and also mulching much thicker. We aim for six inches to a foot of mulch.  Mulch collection has become the biggest task of gardening.  This will get easier – we have also designated rows within the garden to be mixed perennial beds, filled with plants that will be chopped down for mulch:

  • glyrecidia (fast-growing N fixer)
  • cranberry hibiscus (also edible, attracts birds, is pretty)
  • lemongrass (also deters insects, edible)

I will have to report back how successful we are at keeping up with the mulch*, because I am well aware that there is wainaku waiting to sprout under many many square feet of the garden.  There may also be other issues that come up – I know the ants appreciate how well we have responded to their request for a dry area to make their nests.

Rather than digging up the soil and exposing more weed seeds, when we plant now we are mostly transplanting seedlings, tucking them in amongst the mulch.  Some beds we do plant with seeds and transplants and then spread a thin layer of mulch, knowing the more vigorous plants and seeds will make it but some won’t, but this is better for the plants than later disturbing their roots with a lot of weed-pulling.

*February 9, 2013
Here’s the update.
Mostly this experiment of wainaku suppression has worked well. Many beds do still have some wainaku poking through, but it is generally weakened. I think we created an environment that wainaku doesn’t like – more dominated by fungal mycorrhizae and shadier.

As planned, we go after the wainaku that still lurks underground when we harvest root vegetables (ginger, sweet potatoes, taro, turmeric). Beyond that we pull or hand dig. Very little is in the paths.

On the downside, the cardboard and mulch do harbor slugs and ants. Since we are raising 10 baby chicks, I have made it a regular practice to take them and their mom into the garden and lift the cardboard so they can go after the slugs. They aren’t interested in the ants or the ant eggs.

Also, the cardboard is hazardously slippery when it gets wet!

Another downside is that planting seedlings has had mixed results – a whole flat of transplanted bok choys disappeared. Not sure who got them, but Dave did point out that pulling the mulch away to plant the seedlings resulted in a target-like opening for pests and birds.

But overall, it has worked very well. In addition to transplanting seedlings I will be pulling mulch off of some beds and planting seeds, using a very light mulch such as albezia leaves stripped off their branchlets.