University of Kentucky -- College of Agriculture -- Department of Horticulture and Landscape Architecture

CARROT

Daucus carota

CULTURE: Carrots are divided into two groups based on the color of the root (red, yellow, white) and size (short, medium, long). Generally the best quality carrot is deep orange to yellow and medium to short. Carrots like moderate weather with good soil moisture. They grow best at 60 - 70 F. In the RAFT system the roots of the carrots did develop as expected..

SOIL:

The RAFT system uses a commercial growing medium that allows the water to be wicked up through the bottom of the pot from the mat. Carrots require deeper containers for normal growth. We used typical 1 gallon plastic pots successfully. There is no need for plowing, tilling, or soil amendments. There is no need for repeated tilling to loosen the soil to improve aeration. The soilless mix allows for good air movement even though the mix is constantly moist
Standard Field Practice: Plants need a deep, well drained, sandy loam soil. The soil needs to be free of rocks and pebbles that would cause splits and forking of the root.

SEED: 11,000 - 37,500 per/oz.

GERMINATION:

The RAFT system allows the carrot seed to stay constantly moist, not water logged, and not dry out during the germination process. This seemed to improve germination rates. I found that most seed germinated with earlier germination times.
Early growth is slow.

DAYS TO MATURITY:

The RAFT system allowed the carrots to grow continously and uninterrupted (JPEG photo of harvested carrots). Since the RAFT system provides constant water, most plants matured within the expected range of time.
70 - 75 days to maturity

SPACE:

The RAFT system allows you to seed directly into the containers or transplant. There is no need to thin for desired spacing. This results in less seed use. Individual pots of soilless mix allow plants to be spaced at any desired distance. At any time during the growing period, the pots can be re-arranged for more or less space if desired. The RAFT system is also well adapted to "square foot gardening". Plants can be placed on the raft in such a way that all of the growing surface is used. Every available square foot is occupied. The RAFT system eliminates the need for walking paths in the growing area. Each plant receives only the amount of space needed for its growth - resulting in more plants per square foot.
Standard Field Practice: Sow seed in rows approximately 1/4" deep, and approximately 20 seeds per foot. Thin plants to 2" apart

FERTILIZER & pH:

The RAFT system allows a fertilizer to be placed in the water so there is a constant supply of nutrients to the plants. The fertilizer concentrations can be monitored and added when needed. Micro nutrients also can be added to the water. We maintained fertilizer levels at 80 to 100 ppm nitrogen.
Standard Field Practice: pH 6.0 - 6.8. A 5-10-10 fertilizer can be used at time of seeding, however, too much nitrogen can cause roots to fork.

WATER:

The RAFT system allows the plant to have a constant supply of water. However, the soilless mix is not soggy. To keep the water level at a uniform depth, a float valve can be attached to the float beds to fill from a storage tank or hooked directly to a water line.
Standard Field Practice: Carrots need regular irrigation for good steady root growth.

DISEASE: Damping-off and leaf spot diseases (Alternaria and Cercospora)

INSECTS: Leafhoppers, armyworms, carrot worm and aphids

WEEDS:

The RAFT system has no need for chemical weed control. If weeds appear in the pots, they are easily removed by hand. The growing medium is usually weed free.
Standard Field Practice: Chemical control, mechanical cultivation, hand pulling. In the field there is a constant battle with weeds due to a infinite supply of weed seed in the ground that is constantly germinating.

More Information:

Cooperative Extension Service --- University of Kentucky