It does occur to me - it depends on the variety and when you plan to harvest them. If you're planting the long, slender imperator, or if you plan to harvest them as babies, you can probably manage that closer spacing (or at least 2"). Thicker varieties like Danvers, Nantes, and Chantenay, not so much. If you do scatter the seeds and thin later, make sure you cut them off at the base rather than pull them up, so you don't disturb the other plants.

And onions shouldn't be dried all that long in the direct sun either. If your onions weren't finished (matured), were harvested early - which in PA I would think it is too early to be harvesting them - then they will go soft no matter what you do. Onions are left in the dry ground until the tops fall over and the necks turn dry and brown. Then harvested and dried out briefly in partial sun or even shade as it is the air circulation not heat you are after. Now what to do to try to save them. Soak the carrots and beets in ice water for several hours - a cooler full of heavily iced water will help firm them back up some. Then either can or freeze them as they won't store for long as is. The onions can be chopped and then either dehydrated and stored in jars or frozen in pre-measured amounts in freezer bags and used for cooking. Dave

Possibly what you see is what you will get. Both onions and carrots are small seeds and therefore require very fine soil in their bed. I have had good success broadcasting carrot seeds in a well worked bed and then cover with a thin layer of potting type soil (1/8") You might want to start over with the carrots (?) It seems very late to be doing anything with onions. They are light sensitive and should have been planted months ago. Even if you had onion seedlings, it would be very late to be be starting now. Here in Zone 8, I am now harvesting (delicious) Keepsake onions which were planted in mid-August and over-wintered. And also have several long day varieties which have not bulbed yet and were planted as seedlings in March

I just planted two blocks, both about three by three, mixed with radishes. How many carrots can I anticipate? That depends how far apart you thin them, and also how many radishes there are. For instance, if you thin them to one carrot growing in each 2" x 2" space, you'll have 36 carrots per square foot. One carrot in every 3" x 3" space, and you'll have 16 carrots per square foot. You have 18 square feet. Think of this as a learning experience. You'll find out the advantages and disadvantages of carrots at different densities. Another factor is how light or heavy your soil is. I've been planting carrots in wide rows since forever. I've got carrots that don't want to be pulled up. I end up needing to use a trowel for some of them. Obviously when they're too close together, digging them doesn't work well. Another problem when they're too close together is trying to pull the weeds.