May is a Bloomin’ Rough Month

This weekend marks our annual pinot noir release party, and the public inauguration of our home ranch, Torrey Hill Vineyard. It goes without saying that I’m all nerves. Our 2012 rose of pinot noir is a mix of juice from Gap’s Crown (Sonoma Coast) and our own Torrey Hill (Russian River Valley). It’s roughly a 65%/45% mix of that high-pedigree, well-known, name dropping vineyard site with scrappy Torrey Hill. The fruit we harvested last year wasn’t grown under my jurisdiction. Those viticulture choices (pruning, irrigation, pest control, shoot thinning) predated our ownership. But since then, we’ve been working diligently to return Torrey Hill to its former peak physique (back when RoPa* scored it in the 90’s). We’ve replanted dead vines and pruned judiciously. We are dedicated to preserving the gloriously twisted old vines at the north end of the block. But what’s most critical for the 2013 harvest is what’s happening in the vineyard right now. T. S. Eliot wrote “April is the cruellest month” because he doesn’t own a vineyard. May is much worse. Around here, May means bloom. If you drive past a vineyard, you won’t notice much of anything. But if you walk the rows and examine the developing inflorescenses, there’s a lot of sexy going on. Stamens unfurl to reveal their pollen-bearing anther tips. These are boy parts. The calyptra, a cap of fused petals, peels open and dehiscences from the ovary base. The ballooning cap is shed like gossamer layers in a sultry, strip tease burlesque. The swollen stigma (girl parts) is ready to receive pollen. Liberated pollen trickles from stamen tips to the stigma. And the miracle of fertilization begins. If you get an embryo, a grape berry soon follows.

My grapevines are perfect. I’m not just biased because I’m the owner. They really are. Most cultivated varietals are bred to have functional male and female parts. Grape vines are pretty self-reliant that way. Grapevines self-pollinate, usually with great success. There is such a thick concentration of flowers across such a small area, that pollen needn’t travel far to get lucky. Parents: it’s OK to let the kids read this post. Birds and bees are not involved. In fact, insect pollination is of minimal importance in my backyard. What I do care about is heat. According to Dr. Andy Walker at UC Davis, nutrition, disease and competition are important factors too. Luckily this season has been mild, warm, and sunny. We should have an estimate for fruit set and yield in a few weeks. I don’t expect 2013 to repeat the heavy-weight records of the 2012 season, but I’ve got my fingers crossed we’ll yield over a ton.


Year 2010 2011 2012 2013 projection
Yield 0.775 tons 1.017 tons 1.14 tons Wowza!

To recap (or re-cal-yptra), vineyard bloom happens on the micro-scale. Luckily grapevines self-pollinate; their pathetic blooms barely attract a passing flea. During bloom, the “male” anthers mature, open, and release pollen (anthesis), while “lady part” flower caps loosen and fall off. The shedding and transfer of pollen from stamen to stigma lead to fertilization. Pollen germination is followed almost immediately by fruit set.


Petals loosen at their proximal bases until the cap is discarded, releasing the stamens.

 full bloom

Full bloom- Look closely and observe individual flowers about to lose their caps. Others show flowers after stamens have unfurled (anthesis). Each flower has 5 stamens, each topped by a pollen-laden anther.


*RoPa being a one-person moniker like Madonna or J.Lo, not to be confused with couple monikers like KFed, TomKat, or Brangelina

Works cited:

J. E. HEAZLEWOOD and S. WILSON, Anthesis, pollination and fruitset in Pinot Noir, School of Agricultural Science, University of Tasmania, Hobart, Tasmania, Australia

Vitis 43 (2), 65–68 (2004)