Garlic oddities 2012: Is the weather messing with our heads?

This year marks our sixth garlic harvest at Chert Hollow Farm. Overall, garlic has been one of our most reliable crops, and it was a signature item at our market stand. We had some nervous moments a couple years back when we first discovered onion root maggots in the crop. This pest problem continues, but the levels of loss are generally acceptable, and our fingers and noses can usually detect heads that have gone bad before sale or distribution.This year some new concerns and oddities developed in the garlic crop. We suspect that these oddities are weather related, and we’ll describe our observations and reasons for coming to this conclusion. We’d love to hear if other growers saw similar features this year; we know of at least one in the region who has. In spite of this year’s strangeness, garlic will probably retain its “most reliable crop” status, but we’re very glad we’re distributing it through CSA rather than selling each head individually on its own merit at a farmers market this year.

Brief intro to garlic biology
Garlic is propagated vegetatively; it is not grown from true seed (at least not for standard production). Instead, the farmer divides the head into cloves. Each clove is planted (generally in the fall), sprouts, and grows into a new garlic head. Sometime during that growth process, the plant (grown from the original single clove) subdivides a new set of cloves to form the new head. In the spring, hardneck varieties send up a scape (the flower stalk), the heads size up, and the plants start to die back. During this process, the garlic responds to various temperature and day length cues. Temperature, for example, seems to be a big driver of sprouting; a cured garlic head that is cooled to refrigeration temperatures and then warmed again is likely to sprout quickly. In our experience, day length seems to be important in maturation & die-back. Normally, we can put our harvest dates on the calendar for a given variety and be on target within a couple of days, with harvest beginning just after the solstice. Weather is never that stable & predictable, but day length is.

In early spring 2012, the garlic crop looked great. The earliness itself made us nervous; the mild winter meant the crop was up and growing much earlier than usual, and a severe cold spell can damage a crop that gets too far ahead of itself. But by March, we thought  the danger had passed and we were feeling that this year’s crop would rival last year’s spectacular yields.

We didn’t notice anything odd through April. In May, scapes started to come on very early. Eric is in charge of most of the harvest, and he started to mention that he felt there was something odd about the plants, though he couldn’t put a finger on what it was. The scape harvest seemed especially prolonged, lasting weeks with new ones continually popping up when normally it occurs in mostly one tight flush. We kept finding new scapes in beds we’d already gone through, that normally would have produced scapes in a brief pulse. Many plants started to die back very early. We scrambled to fit the garlic harvest into our work load weeks ahead of schedule. Once we started harvesting, we really started to see some unusual features.

Here’s a run down of the major oddities that we’ve observed in 2012:

1) Plants with multiple scapes. Normally, one garlic plant has one scape. This year, we have a number of examples of plants that sent up multiple scapes, sometimes as many as three or four. Upon opening the head, each scape had a set of small cloves surrounding it. What clearly should have been one big clove had subdivided into multiple small cloves. This tended to affect large-cloved hardneck varieties (such as German Extra Hardy). This affected a relatively small percentage of plants in a few varieties; see photo below for an example.

2) Extra “leaves” coming out where the main leaves meet the stalk (please excuse incorrect botanical terminology; I haven’t found a complete diagram of proper terminology for garlic plant parts). Normally, a maturing garlic plant has a central stalk with maybe 10 or so leaves coming off of it from alternate sides up the stalk. This year, we saw many plants with clusters of slender “leaves” coming out of the nodes where the normal leaves met the stalk. Our initial worry was that these were indicative of cloves that had sprouted &/or subdivided (similar to the plants with extra scapes), but this does not seem to necessarily be the case. In heads that we’ve opened, these “leaves” seem to be extensions of the tip of the clove skin that have grown up into a leaf-like structure. This affected a high percentage of plants in most varieties. Our hope is that it won’t affect eating, storing, or planting quality, though having never seen this before we don’t know.

Above left: Normal garlic plant with leaves coming off of central stalk. Center: Odd garlic plant with extra “leaves” coming out of main leaf node; this is a relatively mild example. Right: The extra “leaves” seem to be extensions of the clove skin; internally, these cloves looks normal.

3) Massive excess of skins wrapping the head (sometimes combined with roots that ripped off easily at harvest). Normally, each green leaf corresponds to one wrapper skin around the garlic head. (In fact, we determine when to harvest garlic based on how many green leaves are left so that there are few enough layers to let the head dry properly but enough to hold it together.) However, some of the plants this year had a lot more skin thickness than is normal. Sometimes this makes the heads feel squishy, and it’s not because of rot but rather because of a very thick collection of skins wrapping the head. One head that I opened had a couple little bits of edible clove tucked in the middle of a whole lot of culinarily useless wrappers. This abnormality may have varying degrees of severity. The worst/most obvious cases affected a smallish number of plants in a few varieties, but there are quite a few heads that we’re afraid may have disappointing amounts of actual garlic tucked away inside. Example shown in photo below.

4) Extra-thick skins wrapping under-developed cloves. This seems to be a big problem in our softneck varieties. We noticed that a high percentage of heads felt squishy when we harvested. After a few weeks of curing in really dry conditions that would normally yield a perfectly cured head, the clove-wrapping skins are still thick and moist. Many of the cloves are small. We noticed a bit of an off-aroma in one head that we opened, though the cloves themselves tasted normal.

Our favored hypothesis is that the weather was the primary culprit in this year’s garlic oddities. Here are some lines of reasoning:

1) We think the heads with extra scapes are especially telling. We speculate that the extreme warmth of March (which caused soil temperatures to soar to around 70ºF) caused the heads to think that summer & maturation time had come. April brought more seasonable temperatures & a number of hard freezes in our valley. Did this cause some of the cloves to subdivide, thinking they had gone through an extra year: March = summer, April = winter, May = summer again? A couple of additional observations: Larger-cloved varieties, which were perhaps farther along in the maturation process as of March, tended to show more abnormalities. In addition, late plantings (November rather than October) for a given variety tended to show fewer abnormalities, so perhaps those weren’t as far along in March & less primed for confusion.

2) Too-hot weather is known to interfere with garlic growing. The subject of growing garlic in the south is discussed on a number of websites & gardening forums. Based on information on some of these, variety definitely matters, and overly hot weather does seem to cause premature maturation independent of daylength, more so than we thought prior to this year.

We doubt that we could have completely avoided the oddities that we observed this year. One factor to note is that we mulched primarily with year-old leaves (from our woods) rather than straw last year, and wonder if that made a difference. We had done a side-by-side trial with leaves and straw the previous year and found no observable difference. However, straw breaks down more slowly than leaves, holds more air pockets, and is a lighter color, so in an extreme year like this it may provide more soil-temperature buffering than leaves do, especially in the spring. But would mulching with straw have been enough to make a great crop this year? We doubt it. In future, we will likely move back to using more straw as a precaution. Planting later is an option, as we saw fewer abnormalities in the late planting, but we also saw considerably reduced head size. There was also the confounding factor that some of the later plantings were also mulched with straw.

We will certainly be selecting among and within varieties to be able to handle conditions such as this year; this ability is a major reason we save our own planting stock every year. Once we have a better handle on eating quality of various varieties this year, we may decide to cull a couple that were especially unreliable. Within varieties, we certainly selected heavily for heads that should the most normal characteristics to save for planting stock.

One thought on “Garlic oddities 2012: Is the weather messing with our heads?

  1. This is really interesting. I have never seen or heard of any of these abnormalities. We didn’t experience any of this strangeness with our garlic, except that we did have a couple cases of scapes continuing to come up after we’d already harvested the rest. We didn’t have any frosts in April, so it may be that the temperature fluctuations here in the city had a smaller range and resulted in more normal plants.