The Basics Series: Roots and Water

The Basics Series, as the name suggests, is a series of articles that lay out some of the basics of gardening and plant care – Soils, Mulches, Planting and Staking, Roots & Water, and Plant Fertilization. Our hope is that this series will be accessible to the beginning gardener while also offering some additional information that will prove valuable to those who have been digging in the dirt for a little longer (first lesson: dirt is what’s tracked onto your carpet, soil is what we plant into). If, along the way, you would like additional information on a particular subject, or if you have suggestions for additional blog posts please feel free to leave them in the comments below.

In the practice of any horticultural pursuit, whether it’s professional greenhouse production, vegetable gardening, hydroponics, or backyard landscaping there are several truths or lessons that can be carried from one discipline to the next. Some are important, some are not, some are obvious, some are legend. If there were just one to live by though; one horticultural maxim to live and to grow by, it’s this: To grow a strong root system is to grow a strong plant.

Why, you say? Because it’s not at all a stretch to say that most of the concerns we may have with whatever plants we may be dealing with can be alleviated by an obsessive adherence to this mantra: To grow a strong root system is to grow a strong plant. Are you concerned about pests that may or may not invade your dogwood? Focus on the root system. Do all of the unknowns about plants and planting prevent you from adding the horticultural curb-appeal to your front yard? Focus on the root system. Do your neighbors talk about whether or not they have a “green thumb”? If they do, it may well be gangrene. Don’t worry about green thumbs, focus on the root system.

Do your neighbors talk about whether or not they have a “green thumb”? If they do, it may well be gangrene. Don’t worry about green thumbs, focus on the root system.

The responsibility that a root system has in the healthy growth of a plant is truly astonishing. One way to consider its importance is to understand the similarities between the root system (part of the vascular system of a plant) and the vascular system that lies just beneath your own skin. Both of them are responsible for moving all that is necessary for life from one part of the organism – whether it’s the plant or your body – to the rest of the organism. And just as certain as your body will suffer when one part of your vascular system is damaged, so it is with the root system of plants.

Consider the following:

The roots of a plant play a significant role in the entire plant’s pest and disease resistance. Crazy, no? They play such a significant role that most, if not all, commercial fruit tree growers purchase the plants that they want to grow in two parts: the rootstock and the fruit variety. This means that they buy the root system of one plant grafted to the trunk of another. A Golden Delicious apple tree, for example, may be purchased with a particular type of rootstock that provides the entire tree with better resistance to fungal disorders than another. Or, if apple scab isn’t a concern in the grower’s area, a different rootstock may be used which will reduce the likelihood of aphid infestations. Whether you’re growing a fruit tree or an azalea shrub, the fact remains: the health of the root system determines the health of the tree.

The roots of a plant determine the mature size of that plant. Just as fruit trees can be purchased with different rootstocks for different resistances, they’re also purchased with different rootstocks for different size requirements. The trend toward “dwarf” fruit trees came about as it was discovered that though a particular type of apple tree, for example, would naturally mature at 25-30’ tall and wide, grafting a “dwarfing” rootstock onto the tree would limit the mature size to 15’ or so. Again, you’re probably not starting an orchard but keeping in mind the importance and responsibilities of the root system of any plant that you are growing will be time well spent.

The roots of a plant determine that plant’s resistance to wind. Kinda obvious, I know. But worth noting. Certainly we’ve all seen a small, newly planted tree that’s been blown over by the wind (if it was yours, you can read about planting and tree-staking here). But worse than this (new trees can be fixed), we’ve probably also seen much larger trees that have blown over (unfixable). And oftentimes, if you observe the root system of that tree, you’ll notice that the roots are rotten. Why? Sometimes there was nothing that could have been done to prevent this. Other times – and frequently – the tree was planted too deeply to begin with, or it was planted in the wrong (boggy) area. One way or another, the root system wasn’t cared for. And if it’s not cared for, it won’t do what it’s supposed to do.

Most obviously, the root system gets the water and nutrients to the rest of the plant. Nutrients? Yes. I’d like to highlight that word and the broader concept of fertilization because all-too-often we think of our plants according to the set-it-and-forget-it method of nurturing. We set it in the ground then forget that it needs food. More about nutrition and fertilization next week, though. If you haven’t read our watering guide, you can find it here.

One more feature of the root system (one that many researchers and universities are publishing on) is the symbiotic relationships that the roots form with mycorrhizal fungi. What?!?! Most root systems (about 85% of all plant species on earth) form relationships with one or more of a few different types of fungi and these relationships are mutually beneficial to both parties. The fungus, which colonizes the cells of the root system, receives carbohydrates (energy) from the plant, and the plant receives minerals and an exponentially enlarged root-like network from the fungus. The “threads” of the fungus are so numerous, vast and so thin that they can process minerals that the tree cannot reach. It’s been estimated that this relationship results in the tree’s uptake potential (water and nutrients) growing by a multiple of 50. Wikipedia has a good article if you’d like to know more about mycorrhizae.

So, the roots influence a plants pest and disease resistance. They have a say in the ultimate size of the plant. They keep the plant from blowing over. They take up the water and nutrients that are needed to keep the plant alive. And they are responsible for forming wildly profitable relationships with mycorrhizal fungi (recent research says that the fungi sends out a gas “signal” and the plant’s roots – somehow deciphering this signal – seek out the fungi and initiate the relationship). Fascinating stuff.

Hence: To grow a strong root system is to grow a strong plant.

The obvious question then is, “How do I grow a strong root system”? All that you’ll need to know has been covered in the earlier posts in this series. The first article talks about soil, in general. The second talks about soil amendments. The third talks about planting, depth, and staking. Each of these posts cover topics that are important for understanding the care that the root system needs. Beyond these, take a look at the watering guide to make sure that you’re getting this piece right.

If you have any questions or comments, as always, feel free to leave them in the comments section below. Or you can email Andrew directly:

Previous Posts in the Basics Series:

The Basics Series: Understanding Soil

The Basics Series: Balance in the Soil - Amendments and Their Kin

The Basics Series: Planting and Staking

Next time: A Fertilizer Primer.

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