Getting started: testing your soil

So you want to grow vegetables, and you want to grow them in your back yard soil. Maybe you live in an urban area, and you don't know if your soil might be contaminated with heavy metals. Maybe you just bought your house, and don't know much about the area or your soil. Maybe all three.

Any of these are good reasons to get your soil tested. If you're planning to grow any edibles, especially leafy greens or other annual plants, you'll want to know what you're starting with.

You'll want to test for soil pH, or potential Hydrogen--pH has a huge impact on your plant performance. You can do things to change your soil pH if it is not in a good range for vegetables (you want 6.0 to 7.0). You'll also want to know the extactable nutrients nitrogen (N), potassium (K), Phosphorus (P) at the minimum--these are the most important nutrients for vegetable growth, but not the only ones they need. Commercial fertilizers that have numbers, such as 7-5-4, relate to N, P, and K. Calicium (Ca) and Magnesium (Mg) are important as well, and there are a host of micronutrients which benefit the plants in ways we don't totally understand as yet.

The best test for the money is from U. Mass Amherst--their $9 test will cover soil pH, buffer pH, extractable nutrients (that is, those that are available to plants, based on the pH) Nitrogen (N) Phosphorus(P) , Potassium (K) , Calcium (Ca), Magnesium (Mg) , Iron (Fe) , Manganese (Mn), Copper (Cu) , and Boron (B); the extractable heavy metals (that is, those the plants will take up) Lead, (Pb), Cadmium (Cd), Nickel (Ni), Cromium (Cr), extractable Aluminum (Al); Cation Exchange Capacity, and % Base saturation.

Cation Exchange Capacity measures the potential for your soil to have extractable nutrients your plants need--usually CEC is held in the clay particles of soil. Remember I said clay soil is not so bad? You have to have more than clay to make the nutrients available to plants, but the CEC can show your soil's potential. This can be encouraging for those of us with clay predominant soil.

Base saturation has to do with soil permeability and percolation. You'll want to know how well drained your soil can be, or if it does not drain well.

To take the soil sample, figure out the area of the testing site--maybe you have a space in mind that is 10 feet x 10 feet. From this area, dig down 6 inches (the average root depth) and obtain soil at this depth from several spots evenly spaced within your target site. You'll want to dig 6 to 10 holes in the area, mix the soil you obtain, and from this soil, send 1 cup to U Mass Amherst (or some other extension of your choice). For more specific directions, visit http://umass.edu/soiltest. You can choose to have your results emailed to you (fastest) or snail mailed.

If you have a very large yard, you might consider taking samples from different sections, and sending more than one sample for testing. You'll need to dry your soil sample before sending it. Send it UPS or Fed Ex.

Your results should come back in a week or two. More about reading your results next time.

Don't weed -- Sheetmulch!

If you're serious about wanting no weeds, and you hate weeding like I do, sheet mulching is the technique to use. This technique will build soil fertility over time. It can be used in planting beds, especially with perennial plants. Sheet mulching is an excellent way to keep pathways or bed edges clear of weeds.

The key to sheetmulching is to place a barrier between the weeds and the mulch. There are commercial weed barriers you can buy--they look like black cloth. But they are a waste of money--in a few month's time, the weeds will come through anyway. Instead, get some cardboard boxes, or use a thick layer (quarter inch) of newspaper. The benefits of using these materials is they are relatively durable, and free. Of course, they do break down over time. But when they do break down, in six months to a year, they decompose the way other compost ingredients would, as if you had spread a very thin layer of compost on your soil. Then, in six months when the weeds do grow back (as a few stubborn ones will), they'll be easier to spot, and much easier to pull.

Here's a city tree in front of my house that I sheetmulched. The little square of soil it was planted in was covered in weeds. I covered them with cardboard and 3 - 5 inches of mulch. After it sat like this for a week, and had rained, I planted right into it, poking some holes through the mulch and cardboard, and inserting these irises that had been growing in the backyard.

Steps in sheetmulching:

1) If the weeds are very tall, cut them to 6 inches, or at least flatten them
2) Spread a thin layer of compost (Optional step)
3) Cover the area with cardboard or thick newspaper, overlapping the edges
4) Cover the cardboard with some kind of mulch. Wood chips works well for paths, or perennial beds.

Here is a before and after of an ambitious sheetmulching project. This yard remained weed free for 6 months, and the weeds were much smaller and easier to pull as they grew back.

What is Mulch?

Straw mulch on collards and onions

Mulch in a community garden--wood chips on the paths, straw in the vegetable beds

Wood chip mulch on perennial and native plants

What's mulch? Why mulch?

I mentioned in my last post that soil microorganisms like to stay moist, and since these organisms increase soil fertility, it is useful to keep them happy. Mulching is an easy and cheap way to achieve this result.

Mulch is any soil covering. It is most often an organic matter of some kind--wood chips, oat or rice straw, pine needles, partially decomposed compost--these are all common, free or cheap materials great for mulching. Other mulches that cost money are cocoa hulls, coconut fibers, commercial wood chip mulch, or black plastic sheeting (often used to cover strawberries commercially). Another free mulch material is dry leaves, although it's not as good as some other choices since the leaves can mat, and prevent air circulation to the soil and plants. Some tree leaves may be alleliopathic which means they create conditions that most plants won't tolerate.

In my opinion, no one should spend big money on mulch. Nature provides many excellent materials for free--wood chips can be attained free from a tree trimmer, pine needles can be gathered from under a pine tree, and oat or rice straw (very useful in vegetable gardens) can be purchased for a small fee at horse feed lots or the race track. Sometimes Halloween or Christmas Tree lots give away bales of hay or straw for free when they are done for the season.

The benefits of mulch are many--keeps the soil and thus the plants moist, increases nutrient fertility by benefiting soil microorganisms, lessens the amount of watering needed, keeps weeds down, insulates plants from both very cold and very hot conditions, and loosens soil which makes weed pulling and digging easier. Here in Northern California, where we have a xeric moisture regime (no rain for 5 months out of the year), mulching makes a lot of sense.

Heavy mulches like wood chips, cocoa hulls, and pine needles are good for perennial plants, trees, shrubs, and paths. Straw is best for mulching annual vegetables.

If you want a vegetable garden, and the spot in your yard you have in mind is covered with weeds, the best way to prepare it is to sheet mulch the spot. More about sheet mulching next time.

Easy to grow depends on what you can't see

Maybe the easiest food crop to grow is the potato. Fava beans are a close second. But, it depends.

Don't get me wrong--blueberries are easy too, once you give them what they want, you don't have to bother with them for a while. I gave the blueberries I planted (mentioned in my post yesterday) the acid soil they want, and mulched them with pine needles which are also acidic. I planted them just before a rainstorm, so I wouldn't have to water them. Since they're mulched they'll stay moist between rainstorms, and be insulated from cold weather or heat spells when they come. I probably won't do anything to them for several months, as long as the rain keeps up. I may need to fertilize them with acid fertilizer next Fall, and I'll need to water them periodically in the summer, but there are lazy ways to do that, too. The hardest work will be picking the berries for the next few years. Not bad for a lazy gardener like me.

Here are the four blueberries in their bed (O'Neal is barely visible on the left).

Is it easy to grow food? Sure. It's easy if you give the plants what they want. Is it easy to give them what they want? That depends. If you live in Hawaii, it's very hard to grow pumpkins organically (I've tried) because of fruit flies. And you can't grow blueberries there, because it's just not cold enough. However, I can't grow the large asian guavas that grow there like weeds here in California (at least not yet) without a greenhouse. So, first you have to know your hardiness zone, and then, as I mentioned, you need to know something about your soil. Potatoes and fava beans are easy to grow because they tolerate a variety of conditions, but even they won't grow well in soil with a pH higher than 7, or in rock hard clay conditions.

Even before you test your soil (which is a good idea, and I will get to that) it's important to realize that your soil is not just a collection of chemical compounds. Soil is alive. Maybe you can see worms in it. But worms are not the most important soil animals. The microscopic life forms that live in soil are the heart of what give it the ability to sustain plants. These life forms mulitiply under certain conditions, so if you provide those conditions to your soil, your soil will become more fertile. One of the most important conditions for soil fertility is to keep your soil covered. Uncovered soil dries out, turns rock hard or gets washed away. Even a yard full of weeds is better than a yard of bare soil in terms of fertility potential. The best way to keep your soil covered (other than letting the weeds grow) is to use mulch.

All about mulch, next time.

Blueberries and Wild Turkeys

Blueberry plants are perennial bushes which can grow 3 to 5 feet depending on the type, and have lovely lantern shaped blooms which hummingbirds love to visit. I planted blueberries in my yard this afternoon, as the sky clouded over. Blueberries grow wild in the East coast--I've spent some summers in Massachussets as a child, and still remember picking wild blueberries in the woods. Delicious. Some varieties of cultivated blueberries are forbidden in California, but in recent years varieties have become available that are allowed, and are better suited for our climate.

Sunshine on a cloudy day


Misty in the mist

I planted "Sunshine" which needs only 150 hours of chill time, and seems to tolerate more sun than most types, as well as "Misty" which has lovely bluish green leaves, does well with Sunshine, and has similar low chill time requirements. Both varieties are evergreen, which means they look good in all seasons. These two join an existing Sunshine bush, covered with blooms at the moment, and an O'Neal, which is deciduous, and looks like a dead twig. The tips of the twigs are brown and shriveled , and it doesn't look happy.

Blueberries need acid soil. When you do your soil test, one of the most important things you'll test for is the pH, or potential Hydrogen, of your soil. The pH has all kinds of chemical implications, but the important thing to know is that 7.0 is neutral. Below that is considered acid, and above that is considered alkaline. Most vegetables like a range of 6.0 to 7.0. Blueberries usually like soil with a pH lower than 5.5. However, another benefit of the Sunshine variety is it can tolerate a higher pH than most blueberries. There are many types of blueberry cultivars. If you want to grow them, check with a local nursery to see which types would best be suited to your area, or if blueberries can be grown where you live.

Since my soil pH is 6.8, I first dug out the bed where I would plant them, mixed two bags of acid potting mix into some of the existing soil, and then returned it to the bed. Any potting soil recommended for Azaelas or Rhodedendrons indicates an acid mix, and these plants love acid soil. I set the plants slightly high, and mounded the soil around them, since we have a high water table, and I didn't want the roots to be in the wet.

It could be that the O'Neal variety I planted last year didn't like the wet, or got too much direct sun where I had it before. Or, even with the amendment (I mixed coffee grounds into regular potting soil to increase the acidity) it didn't get enough acid. We'll see how it does with the new mix in this location. Some gardeners I know in the Bay Area only grow blueberries in pots, since they can better control the soil mix. But I think it can work in the ground if you heavily amend to begin with, and continue to add acid fertilizer. The school garden in Oakland has 5 blueberry plants in the ground doing well, with blooms and green berries already formed on a few of the plants. An acid mulch, like pine needles, would help too.

Remember, the secret to success with plants is to give them what they want. First, you have to know what they want, and then you have to know what you have to offer. If your conditions are different from what the plant wants, but you can modify your conditions, you can be successful. It takes more skill (and patience) to grow something that is not suited to the natural conditions you have. Every garden is an experiment, and not every experiment is a success. For example, the O'Neal blueberry may have needs I can't meet, or I may not be able to figure out how to give it what it needs in time to save it. We'll see.

There are many vegetables that are easy to grow in many conditions, and need very little care. If you want quick success, or want to grow food with your young children, maybe blueberries would not be the first thing to try. Or, maybe so--it depends on your personality and sense of adventure--or your soil pH!

I got the blueberries in the ground this evening just before dark. We're expecting a cold snap starting tomorrow morning--temperatures in the 30's and 40's, rain, and possible snow in the hills, which is unusual for us. As I was digging the bed, I heard a noise and looked up to see three full grown wild turkeys alight on my neighbor's roof! This is not a typical sight for South Berkeley. Wish I had a photo to show you, but you'll just have to take my word for it.

Get to know your soil

Today was a nice day in the garden--sunny and a bit warm for February. The kids in the Oakland school garden transplanted pansies and fertilized the fruit trees and blueberries. I'm planning to transplant some blueberries to my yard tomorrow, and all of this gets me thinking about soil.

You want to know the secret to sustaining life on the planet? It's in the soil. Soil is a whole world unto itself, and can make all the difference in the quality of the food you grow--it will even determine what you can grow, or at least what you will start with. If you want to grow food, or really anything, it all starts with the soil.

In permaculture, the basis of all gardening is prolonged and thoughtful observation. First thing to do is go out and look at your soil. If it's covered with weeds, clear a little patch (a foot square to start) and look at the color. If it's dark, that may mean it has the potential to be nutrient rich. If it's red, it may contain lots of iron. If it's pale, it may lack nutrients. The next thing to do is dig up a handful and wet it a little. If you pick out (or sift out) all the little gravel and roots, it's easier to feel the texture. Rub it in your hands. See if you can make it into a ribbon that holds together. Soil has three components when it comes to the rock particle matter--from largest to smallest pieces, there's sand, silt, and clay. Most soil contains all three, but in different amounts. The "ideal" soil for vegetables is a mixture of all three particle types in equal amounts. That's called loam. If your soil feels gritty, that's the sand you feel. If your soil clings together very well, and you can make a pot out of it, that's the clay. Soil scientists classify soils into different textures and types, and for the home garden it isn't necessary to know all that. But a general sense of soil texture is useful to know because that can determine whether nutrients in the soil are available to plants. Your soil may be nutrient rich, but if the plants can't access them, it's as if they aren't there.

Here in zone 9b (I should say, in the East Bay area of zone 9b) we tend to have clay soil. Without even touching it you can tell if you have clay if it clumps together in big chunks when you dig it. If it's impossible to get a spade into it during the dry season, that's a good indication you have clay. Finally, if you walk through a wet muddy field or down a muddy path and if at the end the bottom of your shoes are covered with six inches of hard packed mud, and your feet weigh at least ten pounds more than usual, you'll know that you just walked through clay soil.

O.k., maybe you don't have clay soil where you live. Well, clay isn't all that bad, anyway. I'll tell you more about that another day. The best way to know what nutrients your soil has, before you start loading it with bone meal and other things, is to get your soil tested. I'll talk about how to do that in my next post.

Getting Started: Know your Zone

It's February in Northern California. The weather has been warm, but recently reminds us it's still winter. Today is overcast and in the mid 40's with a chance of rain. It doesn't seem like gardening weather, but in our zone, food can be grown year round. I've got asparagus spears coming up in the back yard, collards, mustard, kale, and chard ready to harvest or soon to be. In the school garden the kids have been harvesting lettuce, daikon, sugar snap peas, kohl rabi, dinosaur kale, and broccoli, as well as chard, baby bok choy, and onion tops. There may be snow on the ground where you live, but in most zones, some food can grow year round. Knowing your zone and what can grow where you live is a first step in planning your garden.

To find your hardiness zone, go to the usda website or do a web search for hardiness zones. The hardiness zones are defined by the average minimum temperature for an area. In Oakland, for example, we are in zone 9b, which means the average temperature does not go below 25 degrees. In San Francisco, the minimum temperature is higher, so they are in zone 10. In Hawaii it doesn't get below 40 degrees, so that's zone 11.

The zones aren't a perfect way to know what will grow where you live. Other factors, such as soil type, humidity, and rainfall will affect what can grow, as well as specific local conditions such as hills and valleys, which create microclimates that can support greater variety than what a zone would suggest. Additionally, when it comes to growing vegetables, one can use cold frames or greenhouses to extend a season. However, knowing your zone is a good start. If you buy bareroot fruit trees, berries, or other perrennial trees and shrubs, you'll need to know your zone to see if what you buy will grow where you live.

The next thing you'll want to do is find out as much as you can about your local soil conditions. That will be the subject of my next post.

It's in our Roots

I started this blog because many people ask me how to grow food, and they want a recommendation of a book or manual. I've been growing food since I was a ten year old child in Hilo, Hawaii, planting the seeds of anything my mom brought home from the store, and gathering advice from friends of family and neighbors. I learned from others, from experience, and later, from reading.

Some years later, I teach gardening and ecology at an elementary school in Oakland, CA, where we grow vegetables and lately maize and wheat in a year round garden onsite. I also manage a community garden in South Berkeley, and grow food in my backyard, along my fence, behind the garage, and basically in any available space.

These days, many people are worried about the economy and an uncertain future, are thinking about growing some of their own food. I want to say that growing food is something that everyone and anyone can learn to do--after all, it's in our roots. All of us, no matter our background, come from people who raised or tended plants for food. In fact, we couldn't grow the crops we do today if they hadn't raised that food, and saved the seeds to plant later.

The main things needed to grow food are the powers of observation, patience, and a healthy respect for the soil. If you don't already have these qualities, you will develop them as you garden. It's also incredibly fun and rewarding, and can even be a spiritual experience if you allow it. I look forward to sharing with you, and hearing of your gardening stories.