The Lowdown on Roots and How They Support Your Garden

The Lowdown on Roots and How They Support Your Garden

By Michael Jenkins | May 25

When we think about plants, we tend to think about the above-ground portion, also called the aerials or the shoot system. And there are good reasons for this—they’re the parts most visible to us and the source of the flowers, foliage, and fruit that we love. However--as is so often the case in life--what goes on below the surface is equally interesting. The roots of your garden plants have their own story to tell. Their development and support they provide are just as important as the parts you can more easily see. By learning a bit more about roots, how they work, and what they do, we’ll understand our plants a bit better and become better gardeners.

Botanically, the roots, are the portion of the plant which has evolved to anchor the plant  and absorb water and nutrition. For most plants, the roots anchor the plant in the dirt and thus develop below the ground, although above-ground or aerial roots do exist! We’ll be focusing on below-ground roots here, just to keep things simple. Air-feeding plants are for a future blog.

While roots grow in a number of different ways, there are two common root structures that home gardeners should be familiar with: the taproot system and the fibrous root system:

  • In a taproot system, the roots grow out from a primary root or taproot, from which the main above-ground stem of the plant emerges. The taproot grows straight down, relatively thick and strong, with smaller root branches emerging from its side. The taproot can fill a number of functions: storing energy for the plant as in root vegetables like carrots, beets, and turnips, or just pushing deeper in search of more water and nutrition.
  • A fibrous root system, by contrast, develops like a dense mat of fiber. Many small roots wind their way through the soil in search of moisture and nutrients, often spreading quite widely in order to do so. These provide thousands of smaller anchor points as opposed to one large taproot, keeping the plant firmly in the soil. Grasses and main grains like corn and wheat have fibrous roots. Perhaps surprisingly, potatoes and sweet potatoes both have fibrous root systems—the big underground tubers are another structure altogether and aren’t technically roots!

So now what we understand the difference between taproots and fibrous roots, what does that mean for our home gardens? The different kinds of roots affect many things, from the role  your plants play in your garden or landscaping to the kind of soil they need. Fibrous rooting plants are good at breaking up or aerating dense soil, and can thrive under conditions that would stifle their taproot cousins. This makes them better for those soil conditions, and helps them play an important role in preventing erosion by holding the soil together. Taproot plants like looser soils, but they’ll go deeper in search of water and nutrition. Thus some taproot plants may thrive during dry conditions, make better perennials, and can help bring water and nutrients to the surface over time.  They also require greater depth of soil for good grown, so if you have shallow raised beds or containers fibrous root plants may be the way to go.

There are some important considerations about roots when transplanting plants. Many seedlings and some developed plants don’t do well when their roots are disturbed—they may wilt, weaken, or even die! These include some popular garden plants like beans, peas, sunflowers, and okra.  As such it’s important to be very careful when uprooting and transplanting or relocating any plant. Making use of seedling trays that allow for minimal root disturbance when transplanting, or larger containers that keep  roots together during relocation can help a good deal in ensuring success.

There’s a lot that goes into fully understanding your plants. Gardening is a process of lifelong learning, and we’re all striving to get a little better every day. Hopefully this helps you understand the role that roots plan in your garden plants, the different types of root structures, and how different plants can use their roots to benefit your space.

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