Coping with Climate Extremes: Smoke and Ash

Smoke acts on growing plants in several ways, and the effects of smoke will vary depending on what else is happening in your area. Temperature, latitude (day length), humidity, and soil makeup will all change the effects of smoke to some extent.  Some effects you can change, and some require you to change your expectations. Here is what we learned last year as we coped with the nearby August Complex fire--the largest in California history at that time.

1. Smoke changes the amount of light plants receive. We got a dramatic illustration of this when it was so dark that crickets sang and we had to use a flashlight at 3pm. Over the next few days, plants in the garden changed their growth habits, some switching from growth to dormancy, others putting all of their energy into flowering or ripening fruit. Plants that are day-length -sensitive will be most affected by this. Tropicals, coming from lands where day length doesn't vary over the course of the year, usually don't notice. Even if they don't react to day length, plants are receiving less light, and light energy is what powers photosynthesis. So growth may slow. Jobs that take a lot of energy, like ripening seed, will be especially affected. Don't depend on size as an index to ripeness. You may have to harvest smaller corn, beans, or peppers.
2. If smoke is thick, it usually changes the heat and humidity patterns as well. It may shade your location enough that temperatures drop. We went from temps in the 90's to the 70's as the smoke thickened. That will slow your plants down. It may make the air more humid and nighttime temperatuures higher if it makes a "lid" that keeps hot humid air from rising and dissipating. It all depends on atmospheric conditions where you are, so monitor the National Weather Service forecasts for your area. 
3. The compounds in smoke can dry out leaf surfaces, just as sprinkling salt on them would. Monitor the actual conditions by digging into the soil to see how much moisture plants have and checking leaves for chemical burns or drying. If you moisten the leaves at all, wet them thoughly; you want to wash chemicals off, not just liquefy them on the leaf.
4. Smoke will cut down the amount of time and energy you have outdoors. Be aware of this at the beginning so you can set new priorities and apportion your time effectively. There's no point in doggedly pretending you can do everything you normally do, then failing at it. Make sure you do what is most important. It might be most realistic (and be best for your health) if you don't start new projects, cut out any jobs that are not essential, and find ways to streamline or reduce the rest. For example, if its getting late in the year, you might get a few more green beans or tomatoes, but maybe the best use of your time this year would be to cut them down and pull a tarp over them so they can compost while you start some winter crops in pots.
5. Flavor can be affected on fruits and vegetables that experience smoke over a long period. And leaf surfaces can become choked with ash or fine smoke particles so that the plant can't breathe. (Plants breathe through holes called stomata in their leaves.) We found that washing plants well with a very fine spray gave them renewed vigor and health. Mist nozzles for your garden hose are available in hardware stores and nurseries or online. They are marketed as a way to get rid of aphids and mites ("Bug Blaster" is one brand) and they do work well for that.  But they work equally well to clean leaves and even some flowers without damage.
6. Ash can affect your plants' growth, and your soil. We found that washing the ash off of our plants produced a dose of dissolved potassium and calcium that gave them an end-of-season boost. Not all gardens will react positively to ash, though. Magnesium, calcium, and potassium must be in balance in the soil. Soil tests are needed for you to know.
7. Depending on how far you are from the fire, smoke may contain different compounds, including acids and oils. Anyone who has burned green pine or fir knows how much greasy "creosote" these woods can produce when green. Should you use a mild soap solution, as you might for aphids? The jury is out on that one. If I were to try it, I would use plain water on half the bed and the soap solution on half, then wait for results before going further. The same goes for neutralizing acids or bases. I would want to test the water running off the leaves. If it is very alkaline, I would consider a foliar spray of very dilute (1 TBsp per gallon) apple cider vinegar.
8. Probiotics will help. The living microorganisms in compost, compost tea, "Effective Microorganisms,"  Bokashi, or any of the Korean Natural Farming preparations will help digest toxins, build a beneficial microflora on leaf surfaces, and help the roots to cope with the changes in soil chemistry. These are generally used as foliar sprays or applied as a root drench.
9. Compost will help. You can dig it in if you are planting for fall, or you can put it around existing plants. Compost buffers nutrient imbalances. 
10. You can also feed microorganisms with prebiotics. For a foliar spray or root drench, you can use a very dilute solution (1-2 TBsp per gallon) of molasses or milk, mixed with a source or biological activity, like compost tea or a couple of tablespoons of yogurt. As a side dressing on the soil surface, mix compost with powdered beets or moisten with the above mixture and apply a thin layer along the row beside the plants.

Recommended plants:
This is a new area for most of the gardening community, and there are few guidelines out there. However, I will share my experience and observations along with what local farmers observed during past fire years.

Plants that have to ripen fruit did the worst. Tomatoes, peppers, and eggplant had delayed ripening. Plants with soft leaves, especially leaves you eat, were affected. Lettuce, for example. Squash, with its big soft leaves and need to set fruit, were adversely affected also.

Beans did better than other fruit-producing plants, possibly because I grow mostly beans that come from marginal environments and are adapted to hot, alkaline soils. Pellegrini romano did well. Rattlesnake, with it's tolerance for marginal conditions, did well. Round Valley (Covelo) beans, Nodak Pinto, Carol Deppe's resilient beans,  Borlotto, and Yessica's Inca Beans all did well. Bush green beans were more affected. Dragon tongue did best, but was less juicy than usual. Provider and the Bush Mix bore poorly and were tough. The purple beans in the mix did better than the green or yellow ones.

Corn was delayed by falling temperatures and reduced light, but Carol Deppe's dry corns matured dry ears in spite of late planting and smoke. The longer ripening period made corn more susceptible to insect damage, but it did all right otherwise.

Sunflowers did well. Brassicas did well; the alkaline ash and reduced temperatures suited them down to the ground. I usually surround my cabbages with ash to deter slugs, anyway. And their waxy leaves resisted smoke damage. Those stalwarts, chard, arugula, and turnips did fine, as they always seem to. Endive also did well, probably because the leaves are more sturdy than lettuce.

I welcome comments from others. As we proceed into new territory, our shared observations are the only guide we're going to have for awhile.