Your carrots full sunlight needs run between 6-10 hours of direct light each day for best results. You can still grow decent roots with less sun but your carrots will turn out smaller and take longer to reach harvest size. Full sun gives you the biggest and sweetest carrots every single time.
I grew carrots in two spots in my garden one summer to test this question myself. The bed with eight hours of direct sun produced roots twice as thick as the shaded bed that got only four hours of light. My shaded carrots also tasted less sweet and took three extra weeks to mature to a size worth pulling from the ground.
Sunlight drives the whole process that makes your carrots grow fat and sweet underground. Those green ferny tops soak up light and turn it into sugar through photosynthesis. The plant then pumps all that sugar down into the root for storage which is the part you actually eat when you harvest.
Carrot sun requirements call for at least six hours of direct light each day for healthy growth. The UMD Extension notes that carrots prefer 8-10 hours of sun when you can provide it in your garden. More light means more sugar which leads to larger roots with better flavor in your final harvest.
Growing carrots in shade works if you accept some tradeoffs in your harvest. You need at least four hours of direct sun or the plants will struggle to put on any size at all. Dappled light under trees can work for you but solid shade from buildings will give you thin weak roots not worth the effort.
In my experience shorter rooted varieties handle low light better than long skinny types. Parisian round carrots and Thumbelina perform well with just five to six hours of sun in your beds. These stubby varieties put their energy into thickness rather than length which works much better when light runs short in your space.
Check your potential carrot spot by watching it on a sunny day from morning until evening. Note when direct sun hits the soil and when shadows take over that spot. Do this check in the middle of your growing season since sun angles change as months pass by throughout the year.
You can boost available light in a partly shaded spot with a few simple tricks. White or reflective mulch bounces extra light up onto your carrot tops from below the leaves. Pruning back nearby shrubs or low tree branches opens up more sky for your growing area to catch more rays each day.
Read the full article: When to Plant Carrots: Expert Growing Guide
