Answer: Carrots are cool season crops but in many areas of the country they can be grown through the summer. To have a continuous crop, plant seeds about 3-4 weeks apart. If you’re reseeding for a late season harvest, be sure to give the seedlings plenty of time before the first frost to mature. Most varieties range from 65 to 75 days.
Carrots need space, so when you are growing them from seed, be sure to thin the seedlings when they are at least an inch tall, giving them at least an inch or more between plants. Covering seedlings with a layer of mulch will help keep them moist.
You don’t mention why you are concerned about the carrots continuing to grow. As long as there is not an imminent frost, just let them keep growing. Cutting back the top would stop the carrots’ growth. Since they are a root crop they need this top growth to continue to develop and send nutrients below the soil. It is important to harvest your carrots before the green growth goes to seed.
I hope this answers you question. Happy Gardening! Karen