All around Northern California right now, you can probably see green. The hills are green, the valleys are green. In a year like this one, the landscape in our part of the “Golden State” starts to look more like the Emerald Isle. I first moved to this area in February, and I was blown away by how much it looked like Ireland.
If it’s a year when the rains start in October, the”greenup” can happen much earlier, even by Thanksgiving. But since our first rains this year came in the second half of November, the grasses and other weeds really didn’t have a chance to get growing before the days got shorter and darker. If you looked closely in December, you could see the little shoots emerging from the soil. But from a distance, the landscape still looked brown and barren.
The crops we grow for soil-building and erosion control — “cover crops” — are similar. We plant them in November, usually just before the first big storm of the year. If that storm happens early in the month, the cover crops will sprout and grow quickly for a couple of weeks and then go into hibernation. But if the rains come just a bit later, as they did this year, the seeds take much longer to sprout and then hardly grow at all until around mid-January when the days start to lengthen.
What you don’t see during the winter is the growth below ground, the roots expanding into the moist soil where they can acccess more of the nutrients the plants will need for accelerated growth. In mid-winter, the root system of many annual winter grasses and other plants is four or more times the size of the above-ground portion. The root systems of “cover crops” are enormous, which is what makes them so good at holding soil in place during wind and rain events and protecting against erosion.
Mid-February, though, is generally when the combination of longer days and warm temperatures kick annual grasses, weeds, and cover crops into higher gear. The nutrients move upwards from the roots, supercharging the plant above ground and they enter into a stage of rapid growth. Some of the vegetable crops we grow over the winter act similarly, particularly onions and garlic, which are both planted in late Fall and appear to stop growing completely most years in mid-winter. Like the weeds, they generally come out of this dormant stage in the second half of February. In uncultivated areas around the farm now, such as field edges and orchards, the grass is almost a foot tall.
Given our fairly high average rainfall at Terra Firma, the seasonal slowing in the growth of the weeds is what allows us to grow overwintering crops at all. That’s because weed control in organic vegetable farming relies 100% on dry weather, dry soil, and dry air. Almost all of our methods of weed control involve uprooting weeds to kill them. But uprooting weeds, whether by hand or by mechanical implements, requires dry soil. Muddy soil sticks to roots, hoes, implements, tractor tires, boots or anything else that contacts it.
Simply uprooting a weed does not guarantee it will die. You need dry air and sunshine to kill the roots. Even fairly small weeds will happily re-root into a new spot if left on the soil surface that is re-wetted by rain or even heavy dew. Some weeds, chopped into pieces, will become multiple weeds in this situation. Cultivating weeds the day before a storm is pointless unless the weeds are removed from the field entirely, which is extremely expensive and time-consuming.
But if we don’t get a chance to kill the weeds at some point during the winter, they become overwhelming once they hit the stage of fast-growth, outpacing the crop plants and eventually choking them out. During Winters that are wet for many months and not-that-cold, we have lost crops to weeds. Most years, we get a nice Dry Spell at some point before this happens. We had one such Dry Spell this year in January — arguably longer than we needed — that gave us the opportunity to get out and kill lots of weeds when they were still tiny. That combined with quite a few days of strong wind and lots of sunshine, means that the farm is unusually “clean” for mid-February.
Now, following a very wet period, we’re about to have a second Dry Spell — timed perfectly for the period of fastest weed growth. We’ve got fields of crops we planted back in January that need to get weeded, as well as the garlic which still needs to get hoed. With a little luck, we’ll be able to get all that done — plus maybe get a few more fields planted — at least a few days prior to the wet weather that I expect will return in March.
If you prefer an Emerald California to a Golden one, you’ll likely enjoy this spring.