Because of our challenging climate here in the Puget Sound region, a good site location is very important. It will make or break your vineyard. Knowing what type of location you have is going to determine what you will plant and how you will plant it. From a grower’s perspective you may or may not have a choice on where you are growing your grapes and under ideal circumstances you can choose a site that is more ideally situated for growing wine grapes.
As with most northern hemisphere vineyards, a southern or southwestern slope is best to get the most heat possible. Good free draining soil is also a must have for grapes since root rot could be a problem in heavy soils. Your location shouldn’t have shading from trees if possible.
The Puget Sound region traditionally goes into drought conditions most summers and drip irrigation can be useful to help start new vines and to help older vines cope in really dry years. Usually we have enough rain in the water table to sustain growth throughout the summer. Sunshine is not a problem during the growing season as we encounter almost no cloud cover for most of the summer. The further from the water, the warmer it will be.
In general, an ideal vineyard in the Puget Sound AVA should have these traits in the Puget Sound to succeed:
- Below 1000’ in Elevation
- Less than 50 inches of rain
- Southern hillside
- No Shade
- Avoid frost pockets or valley floors
- No standing water
- Not too close to the water
Elevation
There is a lot of variation in elevation in the Puget Sound AVA. From sea level to the mountains there are a lot of locations to choose from. Ideally, a vineyard should be located in an elevation range from 200’-800’ but in reality, anything below 1000’ should work. When the elevation is too high, it starts to get too windy, wet and cold. You want to keep the rainfall totals below 50″ a year. Also as you start to climb above 500 feet, the temperatures will start to get cold in the winter and cooler all year long. Sea level elevation generally means the soils are probably too heavy to grow quality grapes and usually too wet. Soils near the sea are dense and don’t easily drain.
Soils
The Puget Sound basin was formed during the last ice age about 10,000 years ago. The Vashon glacier came out of Canada and blanketed the low lands with almost a mile of ice. The glacier extended almost down to the Oregon border. The glacier scoured almost everything in it’s way and ground it up into sand and flattened any prominent surface features. When things warmed up the glacier retreated and upon melting it dropped massive amounts of sand and rocks.
Because of the way the debris was deposited, we ended up with long North/Sound running hills that are mostly made up of this glacial deposit. As anyone knows that has a garden here in the Puget Sound lowlands, we are constantly digging up potato sized rocks. They are everywhere and that is good for growing grapes. That helps keep the soil free draining to a certain point. The typical soil of the Puget Sound AVA, mainly on the hills, is called the Alderwood series. Alderwood soils are typified by good surface drainage and are made up of a rather course texture from gravelly to sandy loam, which grapes really like. The problem is that there is usually a hardpan layer below the topsoil and subsoil that was created when the glaciers sat on top of the ground, compacting the lower soils into a hard concrete like material. When it rains that water can pool on top of the hardpan creating areas underground that store water or create
springs that seem to pop up in the middle of nowhere. The other issue is that grapevine roots can have trouble penetrating the hardpan. The topsoil are usually 2-3 feet thick before you hit the hardpan. Generally, I have not experienced any problems with a hard pan, but if you do, you can simply hire a bulldozer with a ripping tool to rip up the hardpan. On a hobby level, digging a deep hole into the hard pan with a post hole digger can help give room for the roots. Also, rootstocks generally have a shallow root structure and are perfectly happy to grow in shallow soils.
There are, of course, other soils from sandy to heavy clay but ideally you will want to avoid those for a vineyard. If you can’t escape them because it’s the only land you have available, there are ways to fix them that I will not cover here. Please reference a good gardening book that can tell you how to fix your soils, but on a large scale it may not be something you want to tackle.
There is one other issue that you might have to address in your vineyard here in the Puget Sound AVA in the Alderwood series and that is the lack of boron. The glaciers stripped out the boron and it is an essential mineral for pollination. It is simple to fix by applying Boron to the soil or to spray directly on your vines when they have leaves on them.
Also, the soils in the Puget Sound tend to have a large amount of Nitrogen (N). The soils tend to be vigorous and grape vines grow profusely in these soils given enough light and water. There are ways to mitigate the growth of the vines, as we will discuss later.
Proximity to the Puget Sound
I don’t know how many people I have consulted with that wanted to plant a vineyard right at the beach because they had a nice piece of property on the water next to the sound. Being that close to the water can be very problematic. The main reason is that the water is like a giant refrigerator that regulates the temperatures quite effectively not making things too warm or to cold. The water temperature in the Puget Sound is quite cold year-round and even on the hottest days in the summer it is quite cool. While you might be able to have a hobby vineyard that close to the water, a successful commercial operation should be as far from the water as possible. Our vineyard is in Woodinville and the summer high temperatures are always 5-10 degrees warner during the day than downtown Seattle. Also getting some elevation can make a difference too. Cold air sinks and warmer air rises so just climbing up a couple hundred feet can make thing warmer.
Avoid Shade
When I had my first vineyard in my backyard in Bellevue, I lived in the forest with a cleared area in the backyard that got a fair amount of sunshine but shading for the first couple of hours in the morning and then again in the afternoon. Needless to say, the grapes I grew
there never fully ripened. Having as much sun as possible on your vineyard is essential for a fully ripe crop. If you have a few vines in your backyard, try and put it on the west or south side of the house or the sunniest part of your property. If you have a large vineyard out in the open, do not plant next to tree. Trees compete for resources and shade the vines at the same time. In general, any shade is detrimental to getting the highest quality grapes possible. Some of this can be mitigated by picking grapes that ripen earlier. But all day sun is going to be best no matter what.
Avoid Frost Pockets
Frost can occur during the winter months and is generally not a concern in the Puget Sound region. The time of the year that we are most concerned about it is in April and May. Frost moves like water down a hillside which is why grapes are usually planted on a hillside to let the frosty air run off. Frost can collect at the bottom of hills and on flat land. This can cause problems in the spring with tender new shoots. These new shoots cannot tolerate temperatures below freezing and planting on a hillside away from valley bottoms and hill tops is best.
At my location on the hillside in Woodinville, it’s never been a problem. We tried to plant wine grapes, as an experiment, at the bottom of the Sammamish valley here in Woodinville. It did not go well. The vines struggled for about 5 years before we gave up. It was very frosty there in the spring. The vines routinely got zapped by frost where the vines about 400 feet higher on the hillside, never had an issue with frost.
Standing Water
If you have a site in mind and rain water is slow to leave or you have a spring coming out of the ground, avoid these areas as grapes will have a difficult time growing in that much water. Grapes hate “wet feet” which can make the roots rot off if it’s too much, and if it’s not so bad, make the vines grow like a weed. Sometimes, this problem is not easily visible. There are some areas that look dry and if you dig down a foot or two, you’ll see very wet soil. Moss tends to grow over these areas too.
For Backyard Growers
Growing on the side of house or on a trellis in your backyard can give you high quality grapes. In fact it is usually quite a bit warmer next to a house so you can grow grapes that we can’t grow out in a field. Grapes like Syrah and Cabernet if you take the right steps as the heat that radiates from a house is quite warm. Do not grow on a northern side of a house. I wouldn’t even try. We’ll discuss trells systems for a backyard later. The biggest problem for most backyard growers is shade.