By Jodi Bay. This article first appeared in the San Diego Union-Tribune, January 9, 2021, and is reprinted by permission in Let's Talk Plants! September 2021.
Carrots are an easy vegetable to grow and many varieties exist one of which will do well in your garden and delight your palate. Carrots are affected by few diseases or pests. Most issues are cultural, which means issues arise from environmental or growing conditions. With a few tips, your vegetable garden will provide bundles of tasty carrots.
First discovered in Afghanistan around 600 AD, the original carrots were purple, not orange. The first orange carrot was hybridized in Holland in the 17th century and then brought to North America. Carrots currently come in a variety of colors; orange, red, purple, yellow and white. Regardless of color, all varieties are nutritious containing potassium, Vitamin C, Vitamin K, and are rich in fiber and antioxidants.
Carrots are categorized into four shapes:
1. Those that are Taper-rooted or pointed carrots decrease in diameter from crown to root tip. Common varieties are Danvers and Imperator. Imperator can grow upwards of 8 inches and is the variety commonly seen in grocery stores.
2. Stump-rooted or blunt carrots have a blunt tip and are shorter than taper-rooted varieties. A widely available variety is Chantenay.
3. Cylindrical carrots have a slight taper and are named for their shape. They are also short with a blunt tip and are wider than other carrots. Nantes is an example of a cylindrical carrot variety.
4. Ball-shaped carrots are spherical. Thumbelina is a common variety.
Grow carrots from seeds rather than starts. They are a cool-season vegetable which means they grow best when the soil temperature is between 65 °F and 80 °F. In San Diego County, plant carrot seeds along the coast from September through April. For inland, the best months are September through March. They need loose, well-drained soils with consistent watering for healthy growth. Adding compost and a vegetable fertilizer to the soil two weeks prior to planting will help the root grow to its full size and improve drainage. Shorter carrots grow better in heavy soil while longer carrots do best in lighter soil. Ball-shaped and stump-rooted carrots do well in containers and in heavy or rocky soil.
Read the seed package for planting depth but typically carrot seeds are planted shallowly at about an 1/8 inch deep. As the seed germinates, it sends down a thread-like tap root. Keeping the soil damp ensures that water descends into the soil keeping the tap root moist which helps the carrots grow straight. Once the seeds start germinating, thin the weakest plants by cutting the green tops at ground level with a pair of small scissors. This may need to be done a second time as the carrots grow. Carrot season is long in San Diego County so consider succession planting and plant seeds monthly during the cool season.
One issue gardeners sometimes face when planting carrots, or any small seed, is spacing the seeds appropriately to ensure that each seed has room to grow. If this is a concern, purchase or make seed tape. Seed tape is a roll or strip of tissue paper with the seeds already imbedded at the correct spacing. Using seed tape will remove the challenge of getting the correct seed spacing. Instructions on making seed tape can be found at www.homeguides.sfgate.co/make-seed-tapes-carrot-seeds-43521.html. Try it with children. It's fun and a good way to get children interested in gardening. Additionally, there is no rule that carrots have to be grown in rows. Consider scatter or broadcast seeding. It's natural and requires much less work.
A few problems that carrot gardeners should look for are 'forking', 'green shoulders' and 'cracking'. 'Forking' is when the carrot root splits into two or more roots. The cause can be compacted soil, too much water or fertilizer, planting too close, or soil-born nematodes. Good soil preparation and selecting carrot varieties best suited for your soil will help to prevent forking. 'Green shoulders' occurs when the above ground part of the carrot turns green. If caught early, cover the exposed portion with soil. If found after harvest, cut away the green part. The rest of the carrot is edible. 'Cracking' occurs with uneven watering. Overwatering and then letting the soil dry results in the carrot splitting or cracking. Maintain even and regular watering to reduce cracking and improves carrot color.
Pests in carrots are uncommon if soil, watering and fertilization are well managed. Carrots can be affected by wooly aphids, blight and nematodes. For more information on carrot pests, please review the UC IPM Carrot Pest Management Guidelines at http://ipm.ucanr.edu/PMG/selectnewpest.carrots.html
Harvest carrots 70 to 90 days after seeding. The root should be the appropriate size for the variety and be tender. Dig carrots out of the ground. Pulling out by the greens may result in a broken root.
For questions on vegetable gardening or on any other plant, contact the UCCE Master Gardeners of San Diego County Hotline at (858)822-6910 or by email at firstname.lastname@example.org. An additional online vegetable resource is Master Gardener Joyce Gemmell’s Vegetable Planting Guide http://www.mastergardenersd.org/vegetable-planting-guide/.
· 1984 Year of the Carrots Fact Sheet; National Garden Bureau provided by Vincent Lazaneo
· Carrot Production in California. Joe Nunez, UCCE Farm Advisor Kern County; Carrot Production in California (ucanr.edu)
· Notes on Forking Carrots; Charles B Ledgerwood
· UCCE Master Gardener Joyce Gemmell; Carrots.pdf (mastergardenerssandiego.org)
· UC Davis Vegetable Research and Information Center; CARROT.PDF (ucdavis.edu)
· Harvesting Carrots UC ANR; Managing Pests in Gardens: Vegetables: Cultural Tips: Harvesting carrots—UC IPM (ucanr.edu)