Sunday, October 5, 2014

Forest Gardening Q & A

Since I started writing about forest gardening a several years ago, I have received a lot of questions from my readers. I've answered many of those questions for people through email, but I thought it would be a good idea to answer several of the more often repeated questions on this blog for everyone to read.

Question 1: Won't planting a lot of trees use up our water supplies?

Answer 1: I've been asked this question in several different ways by many people. After all, trees are a lot bigger than corn or wheat or squash, so they must drain water supplies faster.

Actually, the opposite is true. Trees are very efficient users of water, and they impact the environment in ways that actually help build up water supplies.

Forests play a major role in the water cycle and help stabilize water tables and maintain freshwater supplies. They do this by promoting water fall in the form of rain and dew (this process is called transpiration), providing shade and mulch to reduce surface evaporation, and slowing down rain run-off (giving rain time to soak into the soil, with the added benefit of preventing soil erosion).
"Trees regulate water supply, keeping it available for their own needs and for those of other plants, for humans and other animals. The roots of the great forest trees penetrate deeply into the earth and draw up great quantities of water which pass through the trees and out through the leaves to create "oceans of the air". Thus the water is kept available for rain. Trees may deprive plants grown immediately beneath but help those at a distance. Forest height and the cooling effect of the water transpired by the leaves can promote rain in the same way as mountain ranges that force the rain clouds to rise and cool. Paul Schreiber, the meteorologist, estimated that a region covered with forest increased rainfall to the same degree as elevating it 350ft.
When rain falls on forest canopies, its force is broken by the leaves and branches so that it seeps gently through the forest debris to replenish the water tables below. Sinking wells where there are no tree belts in the area to maintain water tables can be a dangerous living off capital. Water running off of bared hillsides carries away the soil, not only depriving the uplands but also silting up dams and reservoirs and causing rivers to flood." -- from the essay Trees for a Future

Question 2: Won't birds and animals eat the food produced in a forest garden?

Answer 2: This has been brought up to me twice - once as a sincere question and once as a disparaging accusation. More on the latter in a moment, but first let me answer the sincere question:

Yes, they will eat some. However, I have asked several people with decades of combined forest gardening experience and none of them report ever losing all or even most of a crop due to birds, squirrels, deer or other critters. Forest gardens are no more or less susceptible to foraging by various critters than any other method of growing food (except maybe greenhouses).

Of course birds and animals will consume a small part of your tree crops before you can harvest. Same as they do with other types of gardening and agriculture. And I think that is a good thing.

One of my favorite gardening memories is watching a rather large box turtle munching away on some low-hanging tomatoes in my garden a few years ago. It hung around my garden for about a week before moving on, during which time it ate a number of tomatoes. But I still had plenty left, and the turtle provided some great entertainment.

Which brings up the accusatory comment I mentioned earlier. One person responded to my praise of forest gardening by writing me a rather disparaging note that forest gardens would be totally consumed by birds and wildlife. I was accused of being rather naive. Of course this person had no personal experience with forest gardening, and ignored the multitude of examples of successful forest gardens that have been around for decades in some cases. Oh well... one lesson I've learned over the last few years is "you can't please everyone all the time."

Question 3: Can you recommend trees/shrubs/vegetables/herbs that will do well in my specific area, which happens to be particularly hot/cold/wet/arid?

Answer 3: I have been asked for specific advice many, many times over the past few years. As much as I would love to be able to give that kind of detailed suggestions, I am not a horticulturalist. I am still in the process of learning what grows well in my particular area. The best I can do is point people in the direction of some really good reference books and websites, so that they can research the information themselves:

Edible Forest Gardens (2 volume set) - This two volume set is the best and most detailed explanation of forest gardening that I know of. Includes an extensive matrix of edible and useful plants with lots of detailed information. HIGHLY RECOMMENDED.

Arbor Day Foundation - In the USA, the Arbor Day Foundation's Tree Wizard is a very useful database of trees, including fruit and nut trees. You can look up recommended trees by zip code, hardiness zones, types, height, spread, soil type, sun exposure and growth rate.

How to Make a Forest Garden - This book by Patrick Whitefield covers the basics of forest gardening, including core principles, design and how to choose plants. Also includes over details of over 100 suggested plants for a forest garden.

North American Native Plant Society - Native plant enthusiasts from the USA and Canada. Can connect you with one of the many regional native plant associations.

Finally, I recommend checking out your local resources such as universities with agricultural programs, local community colleges, agricultural extension offices, master gardening courses, gardening clubs, 4-H clubs, etc... Talk to people who are already growing things near you. They will be your best source of what will work in your area.

Question 4: What is that "plant zone" that you keep mentioning?

Answer 4: I am a little surprised that many people don't know their plant hardiness zone, or even what a plant hardiness zone is. But I have gotten that question more than once or twice.

Your choice of trees and other plants will be greatly influenced by your local climate. There is a system called the Plant Hardiness Zones which will make this task easier. Each zone is given a number & letter code which can then be matched to the appropriate code for the trees and plants you are considering. For example, I live in hardiness zone 7b.

Many tree and plant catalogs include information on what hardiness zones are preferred by their plants. In looking through the catalogs, I can easily see which trees and plants would make a good fit for my climate and which would not by matching up the hardiness zones.

To determine your particular plant hardiness zone, click on the link for your particular country or region:

New Zealand
UK & Ireland
Rest of Europe
Israel and much of the Middle East
South America
South America (second map)
China and Mongolia
South Korea
India and surrounding area

For an index to all my Forest Gardening articles, please click here.


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