By Will Bonsall
I can’t think of any other crop which has proven so reliably productive as carrots. I’ve had some disappointing carrot yields on rare occasions, but even then I ended up with plenty of food on the table, even if small or poorly formed. Moreover, due to their growth habit (small footprint with deep taproots) and minimal processing waste, they’re very space-efficient. That’s not including the added efficiency of companioning them with other compatible crops (more on that later).
Carrots (Daucus carota) originated in the Eastern Mediterranean and Southwest Asia, spreading east and west from there. Carrots were known and enjoyed in ancient Greece and Rome, although the roots were probably quite different from carrots as we know them today. “Eastern carrots” tend to be purple, black, red, and white. They also tend to be tougher and coarse-flavored. “Western carrots,” mainly developed in the Low Countries (the Netherlands, Belgium and Luxembourg) and France, are more familiar: orange-yellow, straight, plump, nearly coreless, sweet and mild-tasting. In my experience, the Eastern types are generally inferior as they store poorly and are thus difficult to seed save. The purple varieties in seed catalogs are a recent attempt to combine the two types in search of a tasty carrot in a different color.
The yellow color is from beta-carotene (or provitamin A), whereas the purple pigment is anthocyanin. The white varieties, originally bred from fodder carrots, are generally devoid of nutritional value except for some sugar. Orange carrots are rich in vitamins A, K and B6, and alkaline minerals like potassium and calcium.
Carrots share many traits with their umbelliferous relatives: parsley, parsnips, coriander, fennel, cumin, etc. They’re all quite cold-hardy — in milder coastal areas of Maine they often overwinter in the garden with little or no mulch — due to their various combinations of terpenes (as in “turpentine”) which act as antifreeze. The terpenes also impart various distinctive flavors. The sugars (sucrose, glucose and fructose) give them stored energy for second-year seed generation.
Although carrots prefer full sun, they have some shade tolerance. This makes them adaptable in companion-planting combinations, but also helps to explain why feral carrots (Queen Ann’s Lace) thrive in old hayfields where most other domestic plants gone wild would be quickly choked out. A word about Queen Ann’s Lace: although often referred to as “wild carrot,” that is technically inaccurate. The only truly wild carrots are in Central Asia. What we have in our hayfields are “feral carrots” from cultivated carrots that European settlers brought. However, carrots are quick to revert to their wild traits; I had a cultivated Polish variety go feral from one of my isolation seed plots. That area had been free of Queen Ann’s Lace but, within a few years, it was infested with small gnarly bitter roots, quite unlike their recent ancestors.
Gardeners tend to overemphasize the importance of soil nitrogen. While undeniably important, it acts like a growth hormone and often promotes rapid growth at the expense of general health. This is especially true of carrots. Excess nitrogen (especially with inadequate humus) will yield big carrots with a resinous flavor, which are prone to disease and will not store well. This has to do with the balance between nitrogen and the alkaline minerals potassium and calcium. The latter are critical for sugar formation and the maintenance of turgor (the resilience of cell walls). Without turgor, cell walls become flaccid, wilt-prone and susceptible to the entry of pathogens. Plants respond by producing excessive terpenes, imparting a bitter flavor to the roots.
While overly rich (high-nitrogen) soils are not desirable, an abundance of soluble minerals is helpful, especially potassium and calcium. I never use lime (because I’d have to buy it and I’m cheap) but rather add moderate amounts of wood ash (which I have aplenty) — perhaps a 5-gallon bucket per 1,000 cubic feet. Since wood ash has calcium, like lime, and also abundant potassium and the whole spectrum of other minerals (it is, after all, the residue of deep-delving trees), it is better balanced and more sustainable than mined lime.
Soil should be only slightly acidic, free of stones which lend to deformed roots, and have good drainage. I prefer light soils, but my good friend grows super carrots in nearly pure clay. It’s a compromise between easy taproot penetration with sandier soils and adequate retention of moisture and fertility with clay. Above all, a high humus content will provide a balance of pH and optimal soil moisture, regardless of the sand/clay ratio.
Carrots can be sown very early, though if the soil is too cold they’ll tend to lie dormant until things warm up. Late plantings often need supplemental watering to germinate evenly and maintain steady growth until fall rains. The delicate “forcing” varieties for season extension (e.g., Amsterdam types) need to be pulled as soon as they size up lest they crack and go maggoty.
Fall-dug carrots can be sown in early July or even later in some locales. I seed them rather thickly, say, every half-inch, thinning to about 2 inches apart. Commercial growers who must minimize labor can sow nearer the final desired spacing and just accept that there will be gaps. I make rows 8 inches apart, not because the plants themselves need that much, but because it allows me to hoe between rows.
There is a special method of planting in board-rimmed beds (like raised beds but narrower), say 6 to 12 feet deep, and seeding the entire surface to carrots. Assuming ample compost, minimal thinning in any direction is all that’s required. One can harvest by merely knocking over the boards and gathering the carrots lying there with little or no digging.
I prefer to sow carrots in intensive (not raised) beds, 4 1/2 by 40 feet, with a row of trellised peas down the center. I sow two or three rows of carrots on either side. This combination gives me much more total crop yield per square yard. Carrots also companion well with many other crops, especially beans, lettuce, endive and members of the onion family.
I never add compost to carrot beds, but rather rotate them with a crop which had compost or green manure the previous year. I don’t wish for much debris to get in their way. That said, I do mulch those beds with shredded leaves when the plants are a couple of inches tall. Shredded leaves are very quick and easy to apply as I walk beside the bed with a trashcan full of the shreds and make a blizzard of “confetti” over rows and paths alike. The mulch generally settles down around the plants without needing to be carefully hand-spread. By the following spring much of that mulch will have broken down into the soil and can be shallowly incorporated with a push cultivator — no need to add fertility or further till the soil for the ensuing crop.
Some folks have trouble with carrot fly maggot. For some reason I generally don’t except for rare times when heat and drought stress make them vulnerable. Alternaria blight is also a common carrot complaint. I rarely see it as an issue, and I credit high humus levels, derived largely from tree leaves and grass and no manure, for dodging many problems which plague other gardens.
I’ve known some folks to actually start carrots in plastic seedling trays and transplant for an earlier crop. I realize that for early market crops it may seem worth it, but it never made sense to me, especially in a fuel-heated greenhouse. (I tried it once in unheated cold frames and still doubt the value of it.) The baby taproot is so prone to damage, and a high percentage of the roots were forked or malformed. If I want an early market crop, I will fall-plant, overwinter the carrots in the garden under mulch (though rodents can be a problem), dig in early spring, and refrigerate them.
At harvest time I pull the carrots and top them immediately, as the foliage will continue to suck moisture from the roots. I’m careful to not injure the crown while cutting, leaving about a quarter inch of stem. I prefer to store carrots in layers alternating with crisp newly raked maple leaves in tightly sealed galvanized trash cans. They keep in my damp stone-walled cellar above or near freezing for most of the winter.
By the way, carrots being a biennial, if you wish to seed save, you must overwinter some selected roots, either in the ground if your winters are mild enough or in a root cellar. I’m often asked if storing carrots in buckets or boxes of sand or sawdust is a good idea. It’s a fine way to store carrots for seed, for the same reason it’s a lousy way to store carrots for eating: Carrots stored in a close medium like sawdust or sand will form secondary little rootlets during storage, making them not-so-great for food, but fine for replanting to produce seed. Incidentally, even if you have no desire to save seed, it’s still a great idea to plant some second-year carrots (or parsnips) in or near the garden, as their copious flowers will attract a host of beneficial predators such as syrphid wasps to help in controlling pest insects.
About the author: Will Bonsall lives in Industry, Maine, where he directs Scatterseed Project, a seed-saving enterprise. He is the author of “Will Bonsall’s Essential Guide to Radical Self-Reliant Gardening” (Chelsea Green, 2015). And indeed, he is also a distant cousin of another exemplary Maine horticulturist: Tom Vigue. You can contact Will at [email protected].
This article was originally published in the summer 2022 issue of The Maine Organic Farmer & Gardener.