Do plants get food from the soil?

cabbage plant
Cabbage. Photo: A. Bodkins

People often say you have to feed your plants, but in reality plants make their own food through the process of photosynthesis, which yields oxygen and glucose. Glucose is the food that plants use for energy and growth, they don’t need us to actually feed them. Since plants can make their own food, they are called autotrophs.  The green pigments in plants, called chlorophyll, capture light energy from the sun. The process isn’t nearly as simple as I’ve described it. 

Plants can further be divided into two classifications, C3 or C4, which is determined based on how efficiently the plant can photosynthesize and whether the plant has to go through the process of photorespiration, which is required for C3 plants. This makes C4 plants, like corn, sorghum and  sugarcane more drought resistant because of the complex processes that occur within the plant at molecular levels. The majority of plants are C3 plants. For more information on this topic check out the article from University of Illinois, The difference between C3 and C4 plants

So why do plants need a soil that is sufficient in macronutrients and micronutrients if that is not their food?  Well, the short answer is that nutrients help plants grow and keep them healthy so that they can photosynthesize efficiently. As the plant mass increases, the plant leaf size/surface area increases, which allows the plant to capture more sunlight and turn it into more food.  

You can check out the Home and Garden Information Center’s webpage about fertilizer to learn more about macronutrients and micronutrients. Macronutrients are those elements that the plant needs the most of to be healthy. Water provides hydrogen and oxygen. Carbon dioxide provides oxygen and carbon which are part of the required macronutrients for all plants. The remaining macronutrients are provided by soil (unless the plant is being grown hydroponically, of course). Plants can only take up or use nutrients that are dissolved in soil water. This is why it is so important to make sure that your soil gets sufficient water. Some plants are called heavy feeders and this is generally in relation to their need for larger amounts of the macronutrients, especially nitrogen. Some examples are tomatoes, everything in the cabbage family, and beets.  The University of Maryland provides more information on fertilizing vegetables.  

By providing an optimum growing environment, through correct amounts of light, moisture, and nutrients, the plant will have the best chance at reaching its full potential. As I eagerly wait for the first produce from my vegetable garden this season, I want to be sure that all my plants reach their full potential and produce a large amount of food for me and my family to enjoy this growing season. 

Please comment below with what you are doing this year to ensure that your plants are healthy and happy and growing well. Do you test your soil every 3 years or whenever you are planting a garden in a new area?  Do you research the plant needs (full sun, part sun, or shade) before planting? What questions do you have about managing soil fertility and nutrients? 

By Ashley Bodkins, Senior Agent Associate and Master Gardener Coordinator, Garrett County, Maryland. Read more posts by Ashley.


This year, the University of Maryland Extension Master Gardener Grow It Eat It Program celebrates the resource that supports all life on earth – soil! Look for soil education programs offered by your local Master Gardener program, and visit the Home & Garden Information Center website for more information about soil health.

2022 is the year of soil health

What is soil pH and does it really matter to plants? 

Well, the short answer from a soil nerd (please note soil nerd is not the same as a soil scientist or soil chemist) is that yes it really does matter! Have you ever done the experiment with boiling red cabbage leaves and used that as a pH indicator? It’s a fun science experiment but probably wouldn’t work for determining an accurate soil pH. 

People do not always see the benefit of getting their soil tested; however, if you take a good comprehensive soil sample, the information that you get from the analysis is invaluable. Not only will the results keep you from over-applying nutrients, which has economic and environmental benefits, but also it will ensure that your plants have all that they need right at their root tips.

In my opinion, the most helpful piece of information gained from conducting a soil analysis is the soil pH. PH is a measure of hydrogen ion concentration and tells you how acidic or basic/alkaline the soil is. Most vegetable garden plants prefer a pH between 6-7; therefore, acidic soils need to be amended with calcium carbonate (limestone). Acidic soils are indicated with numbers below 6 on the pH scale which ranges from 0 to 14. Soils in the Eastern US are often acidic, but the natural pH will depend on parent material and other soil factors, such as how the soil has been managed, what plants are growing there, etc. 

It should be noted that some plants actually prefer acidic soils, such as rhododendron, azaleas, and blueberries. Also, some plant diseases, such as scab in potatoes, are worse at a higher pH. Lowering soil pH (often done by adding sulfur) can take several months and may need to be a multi-step process. It is a great idea to test garden soils in the fall, so pH-altering amendments have time to do their job. Here is a great cheat sheet to help you understand what your soil analysis results mean

Another reason that pH is important is that it helps determine the availability of soil nutrients. Soil pH is linked to Cation Exchange Capacity (CEC), which is influenced by soil particle size and the type of parent material (rock). Clay soils will have a higher CEC (sites to hold onto nutrient ions) than sandy soils. CEC will be reported on most soil analyses. If the pH is not in the correct range, then many nutrients are not available to plants, even if you have applied ample nutrients. Thus, in order for the nutrients to support plant growth, it’s important to get that pH correct! This will provide both economic and environmental savings. Check out this link for a neat chart showing nutrients available and pH

The third reason that it is important to check pH is because it can affect soil microorganisms, which are going to thrive at a near neutral level. If the pH is too high or too low you will see a decrease in the number and activity of good soil bacteria, fungus, and more that help to break down organic matter and do amazing other things in the soil profile. (For more details on this topic, download PDF – Soil Acidity Impacts Beneficial Soil Microorganisms, from Washington State University Extension.)

Common questions about soil pH

Can pH change from year to year?

Some forms of nutrients —commercial fertilizers, compost, composted animal waste (cow, horse, pig, chicken manure), organic matter, the weathering of rocks, and even rainfall can alter pH. Fertilizers, depending on the type used, will alter soil pH at different rates. Refer to this PDF – Fertilizers and Soil pH from the University of California.  

Can I use a home soil Testing kit?

I normally steer people away from these types of kits, just because there are so many inaccuracies, especially,  if the kits were not stored at the proper temperature and the directions are not followed correctly, then the results may not be 100% accurate.  

What about electronic soil testing probes?

I don’t have first-hand experience with these probes. I am sure that they do have a level of accuracy; however, I cannot justify the upfront cost. For most gardeners, soil testing every 3 years is sufficient, so in my opinion, it is easier to just collect the sample and send it to a laboratory. 

By Ashley Bodkins, Senior Agent Associate and Master Gardener Coordinator, Garrett County, Maryland, edited by Christa Carignan, Coordinator, Home & Garden Information Center, University of Maryland Extension. See more posts by Ashley and Christa


This year, the University of Maryland Extension Master Gardener Grow It Eat It Program celebrates the resource that supports all life on earth – soil! Look for soil education programs offered by your local Master Gardener program, and visit the Home & Garden Information Center website for more information about soil health.

Are you looking at my soil?

soil in a raised bed

As a first-year college student studying horticulture (and later agronomy) I had no idea what I was in for when I signed up for that first Introduction to Soil Science course. Growing up, gardening and working on my family’s dairy farm, soil was something that we often talked about, mainly if it was wet or dry, rocky or smooth, and of course to stay out of the garden when it was wet; however, I really didn’t understand how important managing it was or how many different parts could be studied!

The technical definition of soil is the natural body composed of solids, liquids, gasses, and living matter that is capable of supporting plant life and has properties resulting from the five factors of soil formation. Wow! A mouthful of words, but a key point from this definition is the word NATURAL— soil is what covers the earth naturally and helps to absorb and disperse solar radiation and precipitation. It also provides an anchor for plant life. With harsh treatment, this living portion can be damaged and thus can take many years to build back. It is important to know too that healthy soils help to mitigate climate change as they store a huge amount of carbon in the form of carbon dioxide (CO2) and organic matter.

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Improve Soil Health for a Climate-Resilient Garden

Soils, plants, and animals are highly interdependent. Soils support and feed microbes and plants which feed animals. Dead plants and soil critters replenish the soils’ organic matter and nutrient supply, completing the cycle. We know that healthy soils produce healthy plants. Many experts believe that improving soil health is the most important thing we can do to make our farms and gardens more climate-resilient. 

Why are soils so important in dealing with climate change? 

  • They store huge amounts of carbon in the form of carbon dioxide (CO2) and organic matter, all of the living, dead, and decomposing plants, microbes, and animals that live in soil. Carbon dioxide is the primary greenhouse gas that is warming the planet. Deforestation, the removal of wetlands and peatlands, and soil tillage cause the release of huge amounts of CO2. Warmer temperatures cause more rapid organic matter decomposition and turnover, especially if soils are tilled and uncovered.
  • Climate change is causing mid-Atlantic weather to be warmer and wetter with more extreme weather events, including periodic drought. This increases the risk of soil erosion and nutrient run-off from intense rainfall, and the risk of plant stress from excessively wet or dry soils. 
Soil from a landscaping project that moved off-site in 2018. Maryland averaged 73 inches of rain that year!
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Worms! – The Garden Thyme Podcast

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In this month episode, we are chatting about the wonderful world of worms. Yes, worms. Although worms are slimy and wiggly, they play a vital role in our ecosystem. Earthworms increase air and water into the soil horizon, and usually, their presence is an indicator of a healthy soil system rich in nutrients and organic matter. Think of them as tiny tillers that incorporate organic matter, air, and water into the soil. 

Timing :
Ecology and Worms:~ 2:25
Vermicomposting: ~ 5:06
Invasive Jumping Worms: ~ 14:26
Native Plant of the month:  Black-eyed Susan’s- Rudbeckia spp.at ~ 22:25
Bug of the Month : Fire Flies/ Lightning bugs at ~29:10
Garden Tips of the Month at ~ 36:00

If you have any garden related questions please email us or look us up on Facebook

The Garden Thyme Podcast is a monthly podcast where we help you get down and dirty in your garden. The Garden Thyme Podcast is brought to you by the University of Maryland Extension. Hosts are Mikaela Boley- Senior Agent Associate (Talbot County) for Horticulture, Rachel Rhodes- Agent Associate for Horticulture (Queen Anne’s County), and Emily Zobel-Senior Agent Associate for Agriculture (Dorchester County).

Theme Song:  By Jason Inc

Beach Books for Veggie Gardeners

All right, maybe not the beach. But as we exit spring and enter the “oh maybe I’d rather stay indoors in the AC” season, I’ve got some recently-published books that might encourage you to get out there and make your garden better (but you can read them inside on a hot day and count that as horticultural education). Want to learn how to identify and deal with pests? Want to know if there’s anything to this “companion planting” stuff? And what’s up with “regenerative gardening”—can your soil really feed your plants? Read on!

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A gardener laments lessons hard won

If only I’d known.  How many times have we slapped our forehead at our gardening follies and mumbled that under our breath.  So today, I am paying homage to the lessons my garden has taught me.  

Soil is god. 

Healthy soil grows healthy plants.  So pay attention to your dirt, um, soil.  Feed it lots of organic matter:  compost, chipped leaves, grass clippings.  And be gentle with it.  Tilling destroys soil structure and harms the soil critters that make soil healthy.

Most bugs are good. 

Only one in ten insects is harmful. The rest are good guys that help control bad bugs.  And another thing.  The uglier the bug, the more beneficial it is.  Look up assassin bugs or cicada killer wasps.  Yikes.  

Assassin bug

Chemicals kill bugs good and bad. 

Most grab-and-go chemicals kill indiscriminately.  Do you really want to take out your allies? I think not. Choose less toxic organic products and do things like hand-picking and crop rotation to keep the bad boys at bay.

Right plant, right place. 

Placing plants where they can not only survive but thrive is smart.  Put a water-loving plant in hot, dry clay and it will die.  Guar-an-teed.  Find out what a plant needs and give it just that for great results.  Don’t tempt fate. 

Plant tags lie. 

Many plant tags have good information, but it goes only so far.  So, do a bit of research online or in a good gardening book to confirm what a plant needs as far as light, moisture, soil and space. 
My beautyberry is 4 feet wider and taller than its tag indicated.  

Respect frost dates. 

Yes, I know.  You want the first tomatoes on the block.  But if you plant them early and they get zapped, you have no tomatoes.  So wait to plant tender seedlings. Mid-May is good. Later is better if your area stays cooler longer.

Always lay garden rakes and pitchforks with the tines away and down. 

Enough said.  

Landscaping fabric is evil. 

Advertised as a weed block, this black devil mesh does nothing but give weeds something to sink their roots into.  Weeds grow both up and down through it.  You will spend half your life wrestling it out of your beds.  

Adopting sickly plants is a bad idea. 

There is a reason they look unwell.  Whether they have been watered too much or too little, baked or chilled, had too much or too little light, or beset by bugs or disease, avoid them.  Smart money is on the healthy plants.  

Impatiens with gray mold

What we do in our garden matters. 

From choosing organic bug controls to making compost, picking drought-tolerant plants to planting flowers for pollinators, every action we take has consequences.  Making earth-friendly choices makes our gardens and communities healthier. 

I hope the lessons my garden has taught me help you to avoid some pitfalls.  In gardening there are oh-so-many ways to get it right.  And wrong.  The fun is in the trying. 

By Annette Cormany, Principal Agent Associate and Master Gardener Coordinator, Washington County, University of Maryland Extension. This article was previously published by Herald-Mail Media. Read more by Annette.