Xtremehorticulture

Read This to Remove Confusion on Pruning Grapes

Q. I read your column about fruit and flowers only growing on 2 year old wood grapevines.  So now I am confused about how to prune my beautiful grape vines. Just what do I remove, or do I even need to remove any of the vines? A. Yes, it can be confusing. Maybe you can think of grapes this way. The first year the plant pushes new growth. There is no fruit on first year growth (first year wood). This new growth must be fully grown and mature to support the fruit that will grow on it the following year (second year wood). This is new growth of grape, a few months old. This growth will produce fruit the next year, second year wood. The second year the plant again pushes new growth from its end or sides (first year growth). First year growth always comes from second year wood. While it is pushing this new growth, it is also pushing flowers and fruit to grow on the previous year’s growth (second year wood). The vine is doing two things at the same time. It is always pushing new growth that does not support fruit (first year wood). At the same time it is pushing flowers and fruit from the previous year’s growth (second year growth). This is a grape flower cluster that will become a bunch of grapes in about five months. These grape flower clusters can only grow from stems or wood, that are growing in their second year. Different grapes produce flowers and fruit in different locations along second year of growth. Some grapes produce flowers and fruit at the very base or bottom of the second year growth (second year wood). This fruit is mostly produced very close to the juncture of the first and second year growth. When pruning these kinds of grapes we only have to leave about 1/2 inch of the second year growth remaining. The rest is cut off.  Immature bunches of table grapes developing along second year wood Removing all of the second year growth except for one half inch results in a “spur” of second year wood. We say that these kinds of grapes should be “spur pruned”. From these “spurs” we allow new growth but this new growth is always cut back again leaving only about 1/2 inch. From these “spurs”, it is a continuous cycle of growth one year and cutting it back to 1/2 inch in late winter of the second year. Growth and cut back to a half inch, growth and cut back to a half inch, etc. Grape vine pruned to spurs. The one year old wood is a nearly totally removed leaving behind only one or two buds. These spurs were left a little bit long because of fear from die back due to winter damage. Just before new growth begins, these spurs will be pruned even more leaving only one bud. Other grapes do not produce flowers and fruit at the base of the second year wood. Instead, they produce flowers and fruit further away from the base at a distance of perhaps 10 or 12 inches from the base or more. When we prune these grapes, we must not cut back too much or we will remove all the fruit. When pruning grapes such as these we must leave very long spurs to accommodate for the flowers and fruit. We no longer call these “spurs” because they are too long. Extra long spurs are called “canes”. Grapes that are pruned so that second year wood is 10, 12 or perhaps 18 inches long are “cane pruned”. Some grapes will fruit only further along the vine. If you spur prune these types of grapes you will remove all of the fruit. These types of grapes must be “cane pruned”. A cane is simply a long spur that has 8 to 10 buds along its length rather than just the one or two on a spur. When pruning grapes it is important to know where the fruit is produced along the second year wood. If the fruit is produced at the base of second year growth, it is “spur pruned”. If the fruit is produced several inches away from the base, it must be “cane pruned”.

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Prune Grapes to Improve Production

Our climate in the Mojave desert can damage grapes during the cold winter months. This winter was warmer than usual and the two times it dropped into freezing weather this winter was when plants were deeply in their winter slumber. That’s good. Freezing weather occurring early in the fall or late spring is typically more damaging than the same freezing weather in midwinter. For small-scale producers and backyard gardeners I like to tell them to prune their grapes last. Wait until the most brutal part of the winter is over and then prune. The reason for this is simple. When we prune grapes we typically remove everything on the plant that is not necessary. When we are finished pruning we leave behind very short Spurs or longer canes depending on the variety of grape. Regardless, for good production we need everything that we have left after pruning to be alive. Temperatures in the Mojave desert can drop to temperatures that can damage grapes. If we prune grapes too early and this is followed by very cold temperatures, we can lose some and possibly most of our production because of the death of these spurs or canes due to cold. Here are some tips on pruning table and wine grapes: 1. When you prune grapes and the temperatures are warm, grapes will bleed. That is, you will see water coming from the cuts. This is normal. This is water being pumped up the vine by its roots in preparation for spring growth. They may continue to weep like this until growth starts and the leaves suck this water away from the cuts and the cuts have a chance to heal. 2. Identify all of the growth that occurred last year. This will be a different color than the older growth or it just will not look as old. Once you have identified last year’s growth, you can cut all of them back so that the new growth is about 18 to 24 inches long. These long canes are where your grapes are going to be produced. 3. Space these long canes which will produce grapes about 12 inches apart. You want to do this for table grapes because this will encourage the berries to become larger. You want to do this two wine grapes because you want to concentrate the flavors developed by the plant into fewer berries. Choose healthy and vigorous canes to be your producing canes. Identify any canes that are between your producing canes. You can either remove these or them back and remove all of last year’s growth. If you remove a cane, you will remove the fruit. Grape pruning progression for spur pruned grapes. Cane pruned grapes are justlonger spurs. 4. The remaining canes will be cut back to about an inch long (spur pruned) or about 12 inches long (cane pruned). If you want to get technical, identify the buds on the canes. When spur pruning, leave only one to two buds remaining. When cane pruning there should be 10 to 12 buds remaining. 5. If you have Thompson seedless grapes, or Black Monnuka do not spur prune them. These should be cane pruned. Make sure you have 8 to 10 buds present on the cane when you’re finished cutting.Most other table grapes are spur pruned. Most wine grapes for our climate are also spur pruned. Here are some previous posts on my blog concerning pruning grapes. http://xtremehorticulture.blogspot.com/2012/12/how-to-prune-table-grapes.html http://xtremehorticulture.blogspot.com/2013/03/spur-or-cane-prune-my-grapes.html http://xtremehorticulture.blogspot.com/2011/10/maxwell-norton-gives-table-grape.html

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Delay Pruning Grapes Until Very Cold is Past

Q. I usually prune my grapes when I do the roses but would like to get a jump on it this year. Will I do them any harm if I prune them now (December)? A. You can do it but I worry a little bit about possible freezing damage if these are winter tender grapes and desiccation. Some grapes are less cold hardy than others. For instance, Thompson seedless has some wine grape heritage (vinifera) and tends to be less cold hardy than some other table types. I have noticed in our desert climate that we can also get winter desiccation (drying out) in windy locations. Those grapes which are pruned to spurs usually leave only one or two buds which means the spur may only be one half inch long after pruning. If we lose this half inch of growth from winter cold or desiccation, then we have lost our crop for the season. I usually delay it until almost the first week in March when buds are starting to swell. By delaying it I can prune out the dead wood that occurs during the cold winter months and focus on the stuff that is still alive. I would wait.

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