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Under the Arbor Issue 30
July 23, 2022

In This Issue:

~ Learning to Surf Heat Waves ~

~ Three Tools for Drought Resiliency ~

Learning to Surf Heat Waves

The kind of heat we've been having makes me wilt, though most of my garden is doing fine. The "bolt resistant" lettuces have finally bolted, preparing to make seeds before yielding to the blistering heat. But they do get fed to my ducks, who love everything green and juicy, even when it's past its prime.

We don't have AC in our 102 year-old house, so our basement is a refuge, where my seed-starting shelves currently house a new crop of lettuce seedlings ready to go out as soon as the heat wave breaks. Next to them are the fall crops for plantout later: kale, cabbage and basil (for patio pots), and oh… and my little redbud forest! Last winter I scarified some redbud seeds with boiling water, put them in the fridge for six weeks, and then planted them in pots. They'll get hardened off and transplanted out after it cools off a bit.

Heat waves will likely come with increasing frequency, so learning to surf them, to ride them till they break, can make us stronger if we look at them through a certain lens. "Suffering through" is a different perspective than "resist not". The heat turns early morning into a very sweet time.

The following "tools" will help our gardens become resilient under heat stress. Taken together, they decrease compaction, radically improve water penetration (and appropriate water retention), and feed soil life, both macro fauna (worms etc.) and microbial (fungi, bacteria, actinomycetes, etc.). It's the life in the soil that make soil soft and spongy, allowing roots and their symbiotic fungi to grow deep and wide in search of water and minerals.

3 Tools for Heat and Drought Resiliency

1) Mulching

Mulch is anything you put on the surface of the soil to prevent sunlight from baking it, thus lowering the heat while at the same time feeding the soil life as it slowly breaks down. Forests and grasslands do this naturally when dead plants, leaves, tree trunks, branches, and other plant material fall and rot on the surface.

Good mulch choices for a vegetable garden are:

  • fall leaves (my fave)
  • ramial wood chips (chipped small branches)
  • very fine (not dyed!) wood chip
  • finely shredded cardboard (easier said than done…)
  • mowed-down or hoe'd-off weeds (preferably without seedheads)
  • homemade finished compost
  • really fine bark chips
  • hay
  • straw

The last two come with a couple of caveats. First off, know the difference between hay and straw.

Hay is alfalfa or tall field grass that has been mowed and (usually) baled. Because it contains the green leaves of the plant it is higher in nitrogen and is used as animal feed.

Straw is the stalks of grain crops (wheat, barley, rye, oats, etc.) that have been cut and had the seedheads harvested for grain, and is mostly used for animal bedding, not feed.

The caveats are that straw has virtually no nitrogen to speak of, and is rather high in potassium, which over time can skew your soil's mineral balance. And (despite what you read on Quora) both hay and straw may contain seeds.

Another, potentially devastating, recent problem with both hay and straw is that it may have been sprayed with persistent herbicides, which can kill your vegetables! And when I say persistent, I mean that even the manure that comes out the back end of a horse may still contain enough herbicide to kill vegetables. (Joe Lamp'l - aka "Joe Gardener" on PBS - had this happen to him.) If you have access to a known organic source, either straw or hay makes good mulch. Alfalfa is harder to apply than straw, because the long stalks hang together, but it's higher in nitrogen than straw, and if you have large areas between vegetable plants you can just plunk down whole "flakes" of it. This is what Ruth Stout advocated in her 1979 classic The Ruth Stout No-Work Garden Book (1979), just republished in 2021.

2) Carbon Farming

"Carbon farming" means keeping something planted, with roots in the soil, at all times. When snow flies and plants die and get covered with snow, they still have roots underground, which feed soil biology in different ways whether alive or dead. Microbial life continues respiring even after the soil freezes, and in most US zones, soil life continues to be quite active below the frostline.

When there are dead roots in the soil, they feed earthworms, microfauna, bacteria, fungi and other decomposers. The earthworms and other tiny animals leave behind manure, which is even more valuable than what we normally think of as "manure" from cows, horses and poultry because of its bacterial and mineral profile. And with enough stuff in and on the soil for them to eat, they can produce more manure per acre than grazing cattle!

When there are living roots in the soil, they do something else that is amazing: they exude up to 60% of the sugars they produce into the soil to attract and feed mycorrhizal fungi. The sugars form aggregates that give soil its structure (sponginess), and fungi exponentially increase the effective foraging zone available to plant roots, bringing back minerals and water.

3) Scratch, Don't Till

Most of us think that tilling will give us a nice fluffy seedbed, free of weeds and easy to plant. But in fact tilling shreds the living fungal ecosystem in the root zone and destroys soil aggregates, which ultimately cause it to cake and harden into compacted soil that sheds water instead of absorbing it.

I now use a surface-scratcher tool, a big "3-tined cultivator" (available from Johnny's or Garret Wade) in the spring to scratch my mineral amendments into the surface without disturbing the root zone, which is now teeming with life.This will be hard or impossible to do until your soil is already loose and fluffy with life, so until it is, fork in your mineral amendments without tilling, and consider also making and spaying microbial teas.

I advise raking any any high-carbon mulch (like bark or wood chips) aside while you scratch in your mineral amendments, to prevent the carbon-breakdown process from temporarily "robbing" nitrogen from the soil and your plants.


Vegetable Garden Guru is dedicated to the renewal of regenerative, sustainable, organic vegetable gardening around the world. May we become gardeners of healthful, nutrient-dense food, careful stewards of soil, and may the plants we tend remind us to always keep growing toward the Light.

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