MSU Extension

For some home vegetable gardeners, most vegetables turn out fine at harvest time, but for some reason their root crops do not develop like they should. So what’s the secret? As Michigan State University Extension horticulture educators and Master Gardener hotline staff knows, there are no real secrets. It’s about understanding how the vegetables grow.

Root crops are those vegetables where we eat the portion below ground. All are considered cool season vegetables that do their best growing in the spring and fall. All root crops prefer full sun, or eight or more hours of direct sun each day. Hot weather causes them to “bolt,” meaning the vegetable produces flowers and seeds and often turns bitter or tasteless when the weather is hot and the plant is stressed. These vegetables include beets, radishes, carrots, turnips, parsnips and rutabagas. Here are some ideas on how to improve your root crops.

Soil is important because it is more than just a place to put in seeds. The heavier the soil, the more difficult it is for these vegetables to expand their edible bottoms in the soil. Having soil that is loosened to about 12 inches deep is one step. Be careful not to till the soil so much that it loses its structure and is broken into tiny particles. When this kind of over-processed soil gets wet, it just repacks itself into a concretion. Mix in about 1/4 of the volume of your tilled soil with compost or composted manure. That means mixing in 3-4 inches into your garden soil. Do it in two applications so it is easier to mix. Your goal is to have 5 percent or more organic matter in your soil.

Get a soil test for your garden. Your root crops need nutrients to grow. The soil pH should be close to 6.5, which is slightly acidic. You can purchase a soil test at www.msusoiltest.com. You will receive a soil test self-mailer with directions and a recommendation will be emailed to you from the MSU Soil and Plant Nutrient Lab after they test your soil.

Both clay-like soil and gravelly soil can impede vegetable roots. Check your soil for obstructions like pieces of wood, rocks or debris and remove the larger pieces. For example, if a carrot root is trying to grow and runs into hard objects, it will develop another root or will grow crooked or misshapen.

After the seeds begin to grow, thin out (remove) the smallest plants. Use the recommended spacing on the seed pack. This gives them root room. Small beet seedlings that are thinned can be cooked just like greens; you don’t have to discard them. Be sure to mulch plants with straw. This will discourage weeds from germinating close to the plants. It also keeps the soil cooler and prevents moisture evaporation so the plants do not have to be watered as often. If using mulch, use something that will break down in one season like straw, shredded newspaper or leaf mulch. Do not use wood chips which may end up as root blockers in future years.

If you do not want to use mulch, you can employ a method called dust mulching by carefully loosening the soil on both sides of the plants so the top half to 1 inch dries out. It has to be redone each time the plants are watered. The dry soil inhibits seed germination, but it cannot be so deep that vegetable roots dry out.

Well over half of the mass of your vegetables is water. This means keeping plants well-watered, typically 1 inch a week divided into several applications including natural rainfall. Buy an inexpensive rain gauge to keep track of precipitation. During hot weather or droughts, more water is necessary.

The one paragraph summary: Full sun, loosen soils and add organic matter. Adjust nutrients and soil pH as recommended by your soil test. Thin out plants for adequate growing room and mulch to keep moisture in and weeds out. Water the plants about 1 inch a week. Now harvest the best looking and tastiest vegetables you can have and these can come from your garden to your dinner plate in under an hour.