Underground plants – also known as root vegetables – are vegetables whose main edible portion is the root. While the leaves of many root vegetables are edible, they’re secondary to the edible part, which grows underground.
When you think of underground plants, you probably think carrots, potatoes, garlic, onions, and beets. Those are all some of the most common options, but you might not realize that there is an almost endless variety of root veggies out there. Jerusalem artichokes, rutabagas, celeriac, jicama, and lotus root are delicious – if less well known – options.
Root veggies are some of my favorite garden plants. They’re incredibly fun to harvest, and if you’re a massive fan of the fall season like I am, they’re perfect for making cozy, delicious fall dishes like a stew. They're particularly nice if you are looking for something that can be stored for a good long while.
Challenges of Growing Underground Plants
One of the biggest challenges of growing underground plants is that you don’t quite know whether you’re going to be successful until you’re close to harvest time. Even then, some root vegetables – like potatoes – are hidden from view until the digging begins.
It’s tough to wait patiently without knowing whether the work and effort you’ve put in are going to reward you in some way. I’ve certainly lost patience in the past and rooted around the earth to spy on my underground plants. Often, the digging interrupts the growth. While it’s best to leave the plants alone, it’s not always easy to have faith in what’s going on out of sight.
Another challenge is that successfully growing root vegetables requires quality soil and a correct nutrient balance. Rocky soil, for instance, will leave you with deformed carrots. Dense, clay soil may cause trouble, too. If your soil has excess nitrogen, your plants may grow big and leafy, but end up with limited growth underground.
One crucial limitation with root veggies is that they don’t like to be transplanted. The process disturbs the root system, which can cause growth problems. Direct sowing is preferable when planting root vegetables, but direct seeding has its own drawbacks in certain instances. It may be too cold to sow root vegetables early enough for a specific harvest date. You may have pests that devour young plants or seeds. To eliminate the risk of losing your young seedlings, and encourage higher rates of germination, use netting to protect your root vegetables from harm.
When conditions are perfect, however, many root vegetables are easy to grow and can be eaten from top to bottom.
Why Grow Root Vegetables?
There are a few good reasons to consider sowing root vegetables for a spring or fall harvest:
They’re super nutritious: Because of the way that they grow, root vegetables soak up a ton of essential nutrients from the earth. Most root vegetables are chock full of the vitamins and minerals important for the human body. They’re also low in calories, so they’re perfect for filling up without going overboard.
You can use the whole plant: Eat the root, but also the leaves (note: not all root vegetable leaves are edible – don’t eat potato leaves!). The leaves are often just as nutritious and are an excellent substitute for other types of greens.
They require little space: While it’s important to thin sowings of root vegetables to encourage healthy root growth, most root veggies can be sown close together and need little room in the garden. Carrots, for instance, can be grown 16 per square foot.
General Care Tips
Regular watering is crucial to prevent roots from splitting. Thin out seedlings early to encourage roots to grow big. Choose disease-resistant varieties to avoid dealing with pest and disease. Mulch to conserve moisture, especially in sweltering conditions. Remove weeds promptly to eliminate competition for your root vegetables.
Types of Root Veggies and How to Grow Them
Aside from potatoes, carrots are probably one of the most popular underground plants. The versatile veggie can be prepared in multiple ways: roast, boil, mash, grate, juice, or eat them raw.
You don’t need much space to grow carrots, just make sure your planting spot is deep enough and your soil is not too heavy and rocky. Use the leafy tops to make pesto or add the greens to dishes as a garnish.
Needs: Even watering and moist soil are required to prevent root deformation. Carrots don’t have many pest and disease problems except for carrot fly. Swallowtail butterflies also lay their eggs on plants in the carrot family (parsley included) and the caterpillars love to eat the foliage. The butterflies will pollinate other plants in your garden, so you can choose to leave them alone, but a large infestation will eventually completely decimate a carrot crop.
Unique challenges: Slow germination is one of the toughest aspects of growing carrots. The tiny seeds are slow to sprout. Because the seeds are so small, people tend to waste carrot seeds, too. Early thinning is important, but it can be tough when seed sprout slowly. Not sure if your seeds are just slow to sprout or are too old to germinate? Try pre-sprouting your carrot seeds to maximize your chances of success.
The first time I grew potatoes, I was amazed that a few sprouted pantry spuds managed to grow once planted in the dirt. I was space-starved at the time, but I really wanted to see what would happen if I planted a potato in the ground, so I grabbed some recycling bins that were lying around the garage and filled them with dirt.
The bins quickly overflowed with foliage. The trouble? I was annoyed that I couldn’t see what was going on beneath the surface!
Needs: Potatoes like slightly acidic fertile soil and should be planted in a location or container that allows for hilling. As you hill up around the tuber plants, the plant roots spread and produce potatoes. Without hilling, you won’t get many potatoes. I also like to add straw to my potato bags. It acts as mulch and keeps the soil nice and fluffy. Your potatoes need full sun to flourish and should be watered regularly.
Unique challenges: It can be hard to know when it's time to harvest your potatoes. Then there's the mystery of what's happening beneath the soil. Noticing a bunch of beautiful leaves and flowers, but once the time comes to harvest, there are no potatoes in sight? Your soil is likely high in nitrogen, which encourages healthy leaf growth, but too much can stunt root growth. Potatoes also require a bit more space than other plants. If you’re not willing to sacrifice an entire bed to a potato crop, consider growing potatoes in bags or large containers.
I love beets because they have a wonderfully complex flavor that tastes like nothing else in the garden. I’m a particular fan of pickled beets and always have a jar on hand to enjoy with winter meals.
There’s something comforting about a sweet pickled beet. Probably because it was a food I often ate during my childhood. Did you know that you can also eat beet leaves? The beet is a close relative of swiss chard – it’s why the seeds look so similar – and the leaves closely resemble the taste of chard leaves. Use them in place of chard in any dish.
Needs: Beets are a cool-season vegetable, so they are best sown in the early spring and in the late summer for a fall harvest. Thin seeds early to encourage sizeable bulb growth. Water plants regularly and plant in full sun. Beets also do fine in partial shade. They will grow slower, however, with less sun.
Unique challenges: Like many other root vegetables, beets don’t bulb properly in high nitrogen soils. Too much nitrogen causes the plant to focus its energy on foliage production. Beets should be harvested sooner rather than later. The longer they sit in the ground, the more likely they are to become tough and bitter. A period of frost, however, will sweeten them right up.
The most mysterious of root vegetables is actually a hybrid. The cross between a cabbage and turnip is often mistaken as a simple turnip, but it’s oh so much more than that. I highly recommend reading Helen Rosner’s New Yorker article about this odd veggie combo.
It’s one of my favorite stew vegetables. To be honest, though, for most of my young life, I was convinced that rutabagas were just big turnips. It made sense when I found out later that this was utterly wrong. The taste is totally different and, in my opinion, much more pleasant than that of a turnip.
Needs: Rutabagas are hardy root vegetables that grow best in full sun and fertile soil. They need lots of water at the peak of the summer season when things tend to get a bit dryer than usual.
Unique challenges: Because rutabagas are a brassica family vegetable, they’re the target of the dreaded cabbage moth. Without insect netting, the larvae of this moth quickly devour young plants and leave them skeletonized. Use row covers to prevent an infestation, but be careful to cover plants early.
I’m indifferent about turnips, but I know that some people love them. I’m partial to the mini turnips I receive in my CSA basket every year. The large version just doesn’t do it for me. I’ll eat turnips, but they’re far from being my favorite vegetable. The flavor is a bit too pungent for my taste.
Needs: While turnips tolerate shade, they should be grown in full sun. In zones 7 and above, turnips can be overwintered. Plant in fertile soil and thin turnips once seedlings are large and strong enough.
Unique challenges: Like other brassicas, turnips need protection from hungry insects. They’re easy to grow, but pests can easily destroy a crop in less than a week if left to their own devices. Another challenge? Turnips left too long in the ground or grown in scorching conditions have a pungent flavor – one that’s an acquired taste. For more delicately flavored turnips, grow them when the weather is cool and always be sure to water frequently.
Parsnips are a quintessential fall vegetable, but they’re not for the beginner gardener – at least, in my opinion. But with patience, they’re a tasty crop worth the effort. They’re best enjoyed after they’ve experienced a frost.
Needs: Their needs are similar to carrots. Remove weeds around your parsnips and remember to keep well-watered.
Unique challenges: The seeds are tough to germinate and slow to sprout. It may take up to a month for parsnip seeds to germinate.
You can also grow Jerusalem artichokes, onions, garlic, sweet potatoes, kohlrabi, yuca, ginger, radishes, celeriac, jicama, and lotus root. Whatever underground plants you choose, you're in for a treat.