Getting the Low Down on Dirt….

The truth is you don’t have to be a biologist, a geologist, or a chemist to be a good gardener but you should pay some attention to a few things early on to assure all your hard work turns into a good harvest later.

One of the simplest things you can do is test the pH of your soil. For just a couple of dollars, you can buy a test kit at most garden centers and in a very few minutes you’ll know if your soil is acidic or alkaline.

It’s so easy. Take a soil sample, mix it with a little distilled water and an additive the kit provides, shake until the additive is completely dissolved, and leave it to “develop” for five or ten minutes.

My compost and my garden soilI tested two samples: the soil in my vegetable bed and my finished compost. I’m not sure if my photo shows the results well but the soil had a pH of 6.0 and the compost was 6.5. Why test my compost separately? Vanity. I’m new to composting and I’m excessively proud of my efforts. I wanted to prove to myself that my compost was relatively neutral – as it should be. Well-composted materials will always be close to a 7.0 neutral reading and will help the soil approach the same. For that reason, I wanted to test my pre-amended soil to make sure it was also within an acceptable range.

Most vegetables do just fine between 6.0 and 7.0. A notable exception is potatoes. They like the soil a little more acidic and, though they will grow in soil with a higher pH, they will be more susceptible to certain diseases like scab.

Why is pH important? Having properly balanced soil allows the plant to absorb the nutrients it needs. I was reading about how this happens on a molecular level and, honestly, it is so complex that my head hurts.

I’m lucky that I can rest on my laurels and do nothing about my pH but what about you? It totally depends on the results you get. This is when knowing the staff at your local garden center pays off. The pH reading you get is probably typical of your region and they will help you pick a soil amendment to correct your specific problem.

Next comes Geology. Soil ideal for plant growth has mineral matter, organic matter, water and air. The mineral content is divided into three categories – sand, silt, and clay – identified by the size of the mineral particles.

On our property, we have a lot of clay: the soil particles are very, very small – microscopic, in fact. Sandy soil has much larger particles, visible to the naked eye. Silt is somewhere in between. Another term you will hear is “loam,” a combination of the three. The type of soil you have will give you information about its texture and (my topic for today) is predictive of drainage.

You can test your soil drainage very easily: dig a hole about a foot deep and a foot wide and fill with water. After it has drained away, fill the hole again. Time how quickly it drains. It should take three or four hours. Faster than that, you could have a lot of sand and will have to amend with something to help hold the moisture. Slower, you may have clay and you need to incorporate amendments to allow water to pass through more quickly.

The Amended Soil in Frank's Cactus GardenHow bad is my clay soil? I picked a spot I knew was most undisturbed clay. The second filling was only half gone after twelve hours. For several years now, we have been mulching the soil in our backyard with wood chips. The obvious reason is to keep down the weeds but as the chips decompose, they add organic matter to the soil, improving its structure. When we put in a cactus and succulent garden a few months ago, to make sure those plants had more favorable conditions, we created a raised bed and added lots and lots of sand to improve drainage. I’ve included a photo to show how granulated the amended soil is.

Why is drainage important? “Vegetables don’t like to stand in water.” That’s what people will say about plants that are sensitive to slow drainage. In reality, waterlogged soils have no room for air – the plants are drowning. Alternatively, if your soil drains too quickly, plants won’t have a chance to absorb enough water and nutrients. Either example of poor drainage can also increase susceptibility to disease.

Wiggly little worms -- Oh, How I Love Thee!While you have that cubic foot of soil dug out, you can do another little test: check your earthworm population. In a cubic foot of soil, you should have 15 or 20 worms (even counting little babies). Earthworms will help your soil structure and will increase the available nutrients. Even as they are adding castings to the soil, their little tunnels help drainage. Earthworms cause no damage to a growing plant – they only consume decaying organic material. If you have just a few worms, the population will grow if you have a healthy, active garden.

The last bit of science I want to talk about relates to seeds I’m starting indoors. Because we are experiencing a La Nina weather pattern this winter, summer will come early but I still don’t have confidence that nighttime lows won’t cause damage. Also, starting them indoors allows me to lavish attention on the seedlings and protect them from pests. When starting seeds, some people use garden soil and/or compost but I prefer a seed starting mix. There are several brands and I don’t have a preference except I am looking for a sterile, soilless mix.

Soilless? This is when the biology comes in. There are living things in the soil. Totally necessary to healthy plant life are good fungi, bacteria and nematodes. But then there are the bad fungi, bacteria, nematodes, plus viruses, protozoa, and more – these are called pathogens. There are pathogens in all soils. But a seedling that has been given a chance to grow and develop a little before set out into the garden is stronger and more resistant to disease.

I can’t tell you how many times I’ve lost a seedling to “damping off,” a deadly infection by a fungus. Now this is interesting because before I figured out the clay soil issue, poor drainage provided the ideal conditions for fungi to infect my young plants. These are not all separate topics but factors that interact closely in a garden.

As I am starting this year’s vegetable garden, these were the things that I found myself thinking about that came from book learning and from more experienced gardeners.

Laurie Gore is the Deputy Heirloom Gardener for Zone 9. She has taken a pH Test and is neutral. She and her husband Frank live in Bonita, California.

by Zone 9 Deputy Gardener Laurie Gore

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Thank you Dr. Brent, we adore your show!!!!And thank you Laurie, your answer is very thorough. Yes, I definitely want to plant tomatoes, but also some wax beans, watermelon, cantaloupe, squash, carrots, beets, green onions, etc. It's my first year as an outdoor gardener, always planted in pots in an apt. in the city —Yes, I'm a transplant too!!! so I have my compost bin going –although it won't be ready for a few months yet, my organic seeds, trays, organic compound, and –probably plenty of sunshine God willing. Thank you also for the link, I'll check it out!

My love to you all, blessings,



As Dr. Brent said, it isn't too late but you want to take advantage of your summer growing season and not wait too long.

I know it is one of my persistent responses, but look into the Master Gardener program in your county (go to to hook up with really knowledgeable local gardeners. The tag line in a lot of the New York state materials is, "Neighbors helping neighbors." That's a terrific sentiment and a good Master Gardener program personifies just that.

In upstate New York, your summer days will be longer than mine but the first frost comes early while mine may never come at all. Remember that it takes about three months for a tomato plant to come to maturity. If you start now, you should have a good harvest in July, August, and September — if not longer. If you have very cool nights, you may want to start your tomato seeds indoors but make sure they have plenty of light. I'm about to post a blog about my problems with that concept so keep an eye on me.

We keep referring to tomatoes while you haven't even mentioned which vegetables you want to start. You might want to check your local sources (the Master Gardeners and your local nursery) to find out the particulars about your area for other vegetables.


Is this too late to start planting seeds?

I/m in Upstate New York.

Thank you!


I'm so there with you. There are a lot of things that I'm doing for the first time this year — or finally doing right (I hope). I'm looking forward to blogging about it and keeping in touch with other beginners.