The Root of the Matter

 

sprout roots cross section

It’s easy to spot possible problems with a plant’s leaves, stems or flowers. Those are the parts we enjoy seeing every day in our garden. But what about the parts that lie beneath the surface of your garden or container?

We can forget all about the roots when enjoying a plant’s shape and color. But some of the toughest tricks to gardening involve root care – watering enough but not too much; soil drainage to allow roots to gather water but not sit in them; ability for roots to take up oxygen, and ability of roots to grow outward to support the plant you see above ground. How do you know your plant’s roots are healthy and why is it important?

Roots Affect Plant Health

The way roots grow, and their health, have a profound effect on the size a plant reaches, its vigor, and how it responds to watering or other care you give the plant. The main function of these leafless, underground stems is to absorb moisture and nutrients from the soil around them. The roots store the plant’s food to keep it nourished and alive. Roots also help stabilize a plant in the soil or potting mix and physically support the plant’s main stem or trunk.

carrot fruit and stems with dirt on the roots
A carrot is a taproot.

Types of Roots

There are various types of roots, although most root systems branch out under the soil. You might have heard of a taproot, which is a primary root that grows straight down into the soil and develops few to no root branches. Picture a carrot. The part we eat actually is a taproot. That’s the good kind, but a taproot can be a problem for gardeners. Some trees, such as pecans, grow deep taproots. This makes them much more difficult to dig up and transplant.

Some roots have lateral, or secondary, roots that branch off from an existing root. This happens with fibrous roots because their primary root eventually stops lengthening. Fibrous roots are lighter and smaller in diameter because they have less cell activity than standard roots.

One of the biggest problems with roots is restriction of their growth. This is easy to see when you lift a new plant out of its nursery pot. Some have roots circling in the shape of the container; the roots received good nutrition from the potting mix and plenty of water from garden center staff, but had nowhere to go. When planting, always dig a hole larger than the root ball – up to three times as large for trees and shrubs. And loosen the soil around the outer edges of the hole. If the ground is compacted and dense, roots will have to work harder to spread.

wilting zucchini plant from disturbed roots
This zucchini looks bad. Because I ripped its roots when I moved the pot.

A second problem is underwatering (especially a tree) or watering in brief, shallow periods instead of long, deep soaks. Short watering doesn’t penetrate very deeply, so the roots grow close to the surface. And that can bring on other problems, including damage from lawnmowers or foot traffic. But with less frequent and deeper watering, roots grow downward as they seek moisture.

Roots as Plant and People Food

For plants, the structure and quantity of roots help determine how much water and nutrition the plant takes in. That’s why it is so important to water a plant more in its first season or year of growth than it will need later. The extra water helps those roots take hold and grow so they can store food for the plant.

Beet roots and leaves are edible.

 

Aside from carrots, potatoes, sweet potatoes, radishes and beets are among common roots people eat. The mature root – a tuberous root in the case of a potato or sweet potato – holds lots of nutrition.

One final tip – buying a plant that has roots wrapped around inside the pot (rootbound) can make for more challenges when you plant it. You should tease or slice the roots near the outer bottom to help stimulate new growth. But if a plant’s roots are brown or dry, move on to another plant.