Carrots are among the most universally grown, if not the best loved of vegetables. Horticulturally, though, they can be quite particular. Even seasoned growers can find them one of the more challenging crops to grow. With their radiant colors, diverse shapes, sizes, and culinary versatility, things would seem amiss if there were no carrots on offer at the vegetable stand. Because of this demand, mastering carrot culture can be well worth a grower's while.
In response to frequent requests for carrot-growing advice, Johnny's carrot-growing team has developed a set of recommendations, starting with these four key elements of carrot culture: Bed Preparation, Spacing, Weeding, & Watering.
Principally, carrots need consistency in their growing conditions: they grow best with no wide swings in temperature or moisture, and straightest and smoothest in deep, loose, fertile sandy loams and peat soils with good moisture-holding capacity. To the extent a grower can influence the environment, these favorable conditions are most effectively achieved through correct bed preparation and spacing, and timely weeding and watering.
Give your carrots a good start by preparing the bed in advance.
Carrots prefer well-drained, deeply-worked soil: preferably to an 18" depth for the longer varieties, though a shallower depth may suffice for shorter varieties. Heavier soils are okay for half-long or round types. (See Diagram of Carrot Types.)
Deeply worked soil minimizes the resistance encountered by the growing carrot roots as they elongate. Resistance can lead to misshapen roots which, while interesting to look at, are more prone to damage during harvest; less easily handled, transported, and stored post harvest; and generally don't sell as well as smooth, evenly proportioned carrots.
Here are the guidelines we suggest for spacing your carrot rows:
- Allow for at least 12" between rows; 18" is ideal.
- Spacing also depends upon the variety grown and its top height. Smaller-rooted or smaller-top varieties, such as Atlas (Parisian Market type), Caracas, or Adelaide, can be packed in a little more closely than some of the larger Nantes and Imperator types.
- Spacing needs are also dictated by the width of the cultivation equipment being used.
- Consider planting pelleted seeds with a precision seeder, to achieve neat, accurately spaced carrot rows and minimize labor and waste. (See below for more about Pelleted Carrot Seed.)
Carrot seeds are small, and their size varies from variety to variety as well as from lot to lot — even if two lots are from the same harvest. Carrot seeds are also elongated in shape, and ridged with spines. These physical characteristics make carrot seeds difficult to singulate when seeding by hand or with seeding equipment.
A range of methods and tools can be used to weed and cultivate your carrot beds; flame-weeding, cultivator tractor attachments, wheel-hoes, and various long- and short-handled weeders and cultivators all have their effective applications.
Carrot do require that a more precise science be applied to the timing of weeding efforts. To minimize labor and maximize results, weeding and cultivating the carrot planting should take place at least 3, and preferably 4 times during the growing season as follows:
Pre-emergence Weeding Schedule
- Weeding or tilling in the weeds several times, before planting your carrots, is ideal.
- We also recommend flame-weeding just before seeding, or just before the carrots seeds germinate.
- One of the most successful pre-emergence timing strategies, particularly for an organic grower, involves placing a sheet of Plexiglass over the first few feet of a seeding and checking it daily. As soon as the carrots began to germinate under the Plexiglass, it's the time to flame weed, because the rest of the stand will begin emerging in 2–3 days.
Post-emergence Weeding Schedule
- If precision pelleted seeds are not used and thinning must take place, the first post-emergence weeding should be carried out as soon as the carrot cotyledons emerge from the soil — this gives the seedlings a head start because their growth will be ahead of the weeds.
- The second weeding/cultivation should take place when the seedlings reach roughly 3–4" in height.
- The third weeding/cultivation should occur when the seedlings are 5–6" in height.
- The fourth time should occur at 7–8" in height.
Watering / Irrigation
The development of a healthy carrot crop requires moisture in sufficient quantities at the correct times throughout the growth cycle — not too dry and not too wet. Here are the specifics.
From Sowing to Emergence
- In the beginning, from sowing to emergence of the cotyledons, low volumes of water should be supplied frequently. Keep in mind that if the soil dries up and a crust forms, seedlings will have a difficult time emerging, and stands will be compromised. To reduce germination issues if a crust does form, your next best step is to make sure the soil surface stays moist, to help mitigate the effect of the crust.
- As the carrot tops begin to develop more leaves, adequate soil moisture should be maintained, but with less frequency and less volume than during the first growth stages mentioned previously. By this time the small plants are established, and the reduction in frequency and volume induces the roots to grow longer.
- Towards the end of the lifecycle as roots are increasing in size, watering should be less frequent but with greater volume.
Drought stress during the first few weeks of carrot plant development can be very detrimental, as is the case with many crops. Germination rates can be reduced and the plants will not get off to a healthy start. Drought stress during carrot root development can often lead to underdeveloped roots that take longer to mature. For small, rounded Paris Market type carrots such as Atlas, insufficient soil moisture will lead to elongated roots by forcing the roots to "reach" for available moisture deeper in the ground.
Conversely, too much soil moisture can have a negative impact. Excessive watering can lead to forked roots, especially when this occurs during the first few weeks after seeding. Excessive soil moisture from over-irrigating or heavy rainfall will often cause growth cracks in carrots. Wide fluctuations in soil moisture can also cause cracking. Excessive moisture in the soil and/or on leaves can also create environmental conditions conducive to certain diseases.
Depending on your location and experience level, providing optimal growing conditions for your carrots can be more difficult to achieve than it is for other roots and tubers, such as potatoes or onions. Like these other vegetable standards, however, there is a steady, year-round demand for carrots. When provided their basic cultural requirements — a properly prepared growing bed, appropriate spacing, and timely weeding and watering — carrots will reward the extra time and attention they are given with their flavor, versatility, and marketability. We encourage you to use the guidelines here to establish generally favorable conditions, then optimize to grow the finest carrots possible in your region.