In The Organic Backyard Vineyard(Timber Press, 2012), expert Tom Powers walks the small grower through the entire process of growing grapes. Learn how to design and build a backyard vineyard, select the best grapes for your region, use the latest organic techniques and store the bounty for winemaking. The following excerpt, taken from Chapter 1, “The Organic Vineyard,” answers the question “Why do you need a vineyard?” and explains how to grow grapes for maximum yield and flavor.
Why Do You Need a Backyard Vineyard?
If you are simply hoping to plant some table grapes to enjoy for home consumption, you do not need a vineyard. You can grow grapevines up an arbor, over a fence, or against a wall. However, if you want to make wine from your grapes–or to sell them to a winemaker–you will need to train your grapevines on a trellis system. Why is this?
Grapevines planted in rows on a trellis work to your advantage in several ways. First, you have a structure on which you can train your vines to grow in a particular way. This structure allows you to observe the growth of your vines and readily spot any problems or pests. The trellis also allows for easy maintenance, and you can customize it to the height of those who will be doing the most work in the vineyard. Finally, straight rows are the ideal layout for using any kind of mechanical equipment in the vineyard, such as a mower or tractor.
It’s not just for your benefit that you need a properly planned and trellised vineyard. Your grapes also benefit. A trellis with an irrigation system makes it possible to provide even and consistent watering and fertilization, which promotes healthy growth. And perhaps most importantly, the vertical trellis is the vehicle that allows the sun to reach the leaves, which is essential for producing good fruit.
First you probably want to know how much wine you can expect to make from your vineyard. Although it’s true that even a small suburban lot can house a vineyard, there is not much point in going to the trouble and expense of constructing one if it will not produce enough fruit to meet your needs. This Vineyard Yields table provides a basic idea of how much land you will need to produce your own wine. Space requirements will vary depending on your vine spacing and the variety, and the productivity of your vines, but it will give you a good general guide.
Keep in mind that your yields (the amount of grapes you can expect to harvest, measured in tons per acre) will also depend on your climate and how well you manage the vineyard. Also note that organic vineyards typically have lower yields than non-organic vineyards, and that yields can vary from year to year.
How to Grow Grapes for Maximum Flavor
The most crucial need that grapevines have is sunlight. Like most plants, grapes need this sunlight in order to undergo photosynthesis. This is the process by which the green tissues of the plant (primarily the leaves) absorb energy from the sun to convert carbon dioxide (CO2) to sugar (which could be called sugar production). The vine then stores this sugar in its woody tissue in the form of carbohydrates, or starch. The following year, these carbohydrates fuel the growth of the vine and the development of fruit (see an illustration of this in the Image Gallery).
Not only is sugar one of the flavor factors in fruit, but it is also sugar that converts to alcohol during fermentation of the fruit. Unless you have a vineyard that allows for a good photosynthetic process to take place, your grapes will not have sufficient sugar levels to make good wine.
Once you understand how to plant and train your vines in such a way that the leaves get maximum sunlight, you can enhance the photosynthetic capacity of your plants. This means, first of all, that nothing can be shading the vineyard, including an adjacent row of vines. It also means that you do not want too many leaves or excessive vigor so that the outer leaves shade the inner leaves. Shaded inner leaves do not do any good and, in fact, are a drain on the plant’s stored energy. What you will ultimately want to develop is an open canopy, which will allow the most sun to reach the most leaves. This open canopy has other benefits, including improved air circulation that helps to prevent fungal diseases, which are prevalent in most vineyards worldwide.
Grapevines also have specific temperature requirements. Grapes do not grow in the desert because temperatures above 95°F (35°C) shut down the photosynthetic process. If temperatures are less than 50°F (10°C), photosynthesis will also be inhibited. Somewhere between these two extremes is the place to be. However, warm winters are not necessary to have a vineyard. Grapevines are deciduous plants that go dormant in the winter. Cold weather, ice, and snow do not have a negative effect on vines, except in cases of extreme winter lows.
Grapevines also need water. As the roots absorb water, the moisture is drawn into the leaves where it evaporates in a process known as transpiration. On the underside of each leaf, there are microscopic pores called stomata, which evaporate the water drawn up from the root system. Daytime sunlight induces the pores to open; at night they are closed. The rate of transpiration is closely linked to the process of sugar production.
Interior leaves in dense canopies may be exposed to such low light levels that their stomata do not completely open. So it stands to reason that leaves that are shaded have lower rates of transpiration, less photosynthesis, and thus less sugar production. Exterior leaves on a grapevine canopy are exposed to higher sunlight levels and temperature, and thus transpire more than shaded interior leaves.
Maintenance of the vineyard is primary in order to encourage photosynthesis. I will give you practical steps to take to allow the photosynthetic process to continue at the highest possible rate. Remember, maximum photosynthesis creates maximum sugar, the best fruit, and thus the best wine.
The Organic Backyard Vineyard
An organic backyard vineyard is one that is grown without the use of any synthetic fertilizers, weed killers, insecticides, or other chemically manufactured products. To be able to sell your grapes as organic, the vineyard must be certified by an organic organization such as the National Organic Program (NOP), the National Sustainable Agriculture Information Service (ATTRA), or the Canada Organic Regime. In addition to these federal organizations, there are organic and sustainable farming organizations at the state and provincial levels.
Sustainability is a process of growing crops using practices that do not use up the natural resources of the land, but rather enhance and improve them. A sustainable farmer or grower aims to prevent soil depletion and erosion, water pollution, loss of biodiversity, and ecological impacts from crops. That means improving the texture and fertility of the soil by planting cover crops and using amendments such as compost and manure. Above all, the sustainable grower encourages resilience in the crops rather than chemical dependence, and uses the resources at hand to help maintain good health in the soil, water, and crops.
Managing Problems Organically
The concept of Integrated Pest Management (IPM) was developed by the University of California, Davis. This system follows the principle of employing the least toxic pest control practices. Instead, it aims to harness existing methods of control whenever possible. For instance, one way to encourage natural pest control is to maintain a nearby hedgerow of native and other plants that attract beneficial predator insects like wasps and spiders. These insects in turn feed on vineyard pests such as mites and thrips. I have such a hedgerow alongside my own vineyard. In addition to using such principles, the sustainable grower will choose organic pest and disease control products that can address the most common problems faced by grapevines. Spraying basic elements like sulfur and copper to combat fungal diseases is one example.
The greatest concern of an organic vineyard is that a pest or disease may invade that is not treatable by anything other than a chemical compound. But this is becoming increasingly rare as more organic treatments are developed. In my experience, this has not been an issue.
I believe you can have an organic vineyard almost anywhere you can have a vineyard. If you already have a conventional vineyard, you can convert it to a more organic and sustainable vineyard by eliminating chemicals and improving your soil health and vineyard biodiversity. Under the National Organic Program, you may even be certified over a three-year transition process.
Of course, you do not need to be officially certified in order to grow your own grapes for winemaking. But an organic and sustainable vineyard is still a good choice for home growers and winemakers for a variety of reasons. One is that handling chemical pesticides often requires permits and extra precautions, by anyone who is working in the vineyard and even by your neighbors. These products also cost money; an organic vineyard is generally less expensive to run than a conventional one (although it may take more labor). Finally, you can contribute your part to being less of an impact on your community and the world (see the Image Gallery for regions suitable for growing grapes).
This excerpt has been reprinted with permission from The Organic Backyard Vineyard: A Step-by-Step Guide to Growing Your Own Grapes by Tom Powers, published by Timber Press, INC.