The best way to know when to plant carrots is to take the soil temperature with a soil thermometer. This looks just like a meat thermometer but it reads down to zero degrees. If soil temperatures average 50 degrees or above carrots can be planted.
To get a good average of the soil temperature use the soil thermometer between 9-11 AM when the night time cold has worn off but before the afternoon sun inflates the temperature.
Carrots are a root vegetable and like other root vegetables they are a cool weather crop. Carrots grow best with air temperatures between 55 and 70 degrees. Lower temperatures between 40 and 55 about 2-3 weeks out from harvest may make carrots sweeter.
Is It Too Late to Plant Carrots
The latest carrots should be planted is 70 days before the first frost. Carrot varieties take between 70-120 days to mature depending on the variety so if your short on time choose a fast maturing variety.
Carrots can be picked early before reaching full maturity when they are finger size. This is what baby carrots are, just carrots picked early.
Carrot plants can handle a light frost but by the time it comes the carrots should be somewhat developed. Temperatures below 50 degrees will slow down carrot growth. Temperatures between 55 and 70 degrees lead to the best growth.
Germinating Carrot Seeds
You can germinate carrot seeds indoors in starter trays, or in paper towels in a ziploc bag, or direct seed them into the ground.
- Indoors in a starter tray seeds will germinate in 5-10 days. A heating pad is not necessary but can speed up the carrot seeds germination and increase germination rates. Read “starting carrots indoors” below for more on starting seeds in a starter tray.
- To germinate carrot seeds indoors with paper towels get four pieces of paper towels and wet them with water. Wring them out so they aren’t completely soaked. Lay out two pieces of paper towel and spread out the carrot seeds on top of the sheets. Then lay the other two pieces of wet paper towel on top of the carrot seeds. Place the paper towels and seeds in a ziploc bag and put the bag somewhere warm between 70 and 85 degrees and dark. The hotter it is the more often you need to check the paper towels to see if they have dried out and sprinkle water on them if they have to keep them moist. After 2-3 days the seeds should sprout. You can tear pieces of the paper towel to not disturb the sprouted root and plant it with the small piece of paper towel attached.
- Germinating carrot seeds directly in the ground can take 1-3 weeks. They will sprout faster with warmer weather and slower with cooler. Keep the soil around the planted seeds moist and don’t water with cold water below 50 degrees.
Starting Carrots Indoors
Starting carrots indoors is a great idea to increase germination rates, extend the growing season, and give carrot plants a great start. Avoid root shock when transplanting outdoors by using a starter pot like Cow Pots that can be planted directly into the ground. Cow pots are environmentally friendly and made by a third generation American dairy farmer.
Use a seed starting mix or potting soil to fill the starter tray. Seed starting mixes are a mixture of organic materials that are very light and loose and provide a texture that allows easy root growth. Potting soil will also work fine. Either one will have enough nutrients in the mix to last the seedlings until they’re transplanted. Filling the trays with garden soil is generally considered a no-no because of possible pests or disease in the soil.
Once the starter trays are filled with your selected growing medium put a carrot seed on top of each pot. Take a pencil and push the seeds down into the soil about 1/4″. Then cover the seeds with some dirt and gently water the pots.
Gently water starter trays from the bottom. This is done by filling a tray with about a 1/4″ of water and setting your starter pots in the water. Check the starter pots by feeling the top of the soil every 20 minutes. When the soil on top feels moist the water has worked its way up through the containers. Empty the remaining water in the bottom of the tray.
Lifting a starter tray up to feel how heavy it is is a good way to know when to water. Use water that’s at least room temperature. If you’re starter tray is under a grow light, on a heating pad, or in a hot area expect the soil to dry out sooner.
The amount of light seedlings get will make or break the small carrot sprouts. A south facing window sill is likely not enough, especially in cloudy winter days. The temperature right next to the window is likely cooler than you want the seedlings to be.
Try and keep the starter tray in a warm area that stays between 70 and 85 degrees. Even though carrots are cool weather plants that grow best with temperatures from 55-70 degrees, germination will be faster and more successful with warmer temperatures.
If you have a three seasons room or room with lots of south facing windows you’re starter plants should do fine. If they don’t get enough light the stem will get spindly stretching for light and the plant will fall over on itself. Ideally you have supplemental lighting.
If you have a small space or only want one starter tray of seedlings this kit includes a tray with a dome, a small light, and heating pad. I used a T-5 Fluorescent for years and they’re great for vegetative growth.
They can be used for a plants whole life cycle to flower and fruit but their not ideal for it. This T-5 light measures 2×4′ and will cover an area of 4×4′ very well and an area of 4’x6′ well. At the ends of the 4′ ballast light stops abruptly but on the sides it casts outwards.
T-5 fixtures like this have 8 bulbs and two power switches that allows you to operate 4 bulbs independently. The bulbs last for about two years with nearly full time use. LED lighting is another option that costs 3-4x initial cost but uses 1/3 of the electricity. Lush Lighting I know produces quality LED lighting.
Do Carrot Seeds Need to Be Soaked In Water Before Planting?
Carrot seeds do not need to be soaked in water before planting. The point of soaking seeds is to increase germination rates. Hard seeds like watermelon, corn, or bean seeds benefit from being soaked and the outer shell softened making it easier for the seed to sprout.
How Far Apart to Plant Carrot Seeds
Plant carrots every 1″ apart in mounded rows spaced 12″ apart. When carrot sprouts reach 3″ thin down to one carrot plant every two inches. If you’re doing square foot gardening you want 16 carrot plants per square foot.
Bigger varieties of carrots may need more spacing between carrots and if top growth is also known to be big rows may need to be spaced further apart as well. Mounded rows increases soil temperature and drainage.
Remember to water with room temperature water after planting to help germination.