You are taking a big chance planting directly to ground. A better idea would be to start them in a small pot4-6", or a SOLO cup with a couple small holes (a hot 16p nail does just fine), near the bottom for drainage
After you see that you have viable plants; You can make a more informed decision on what to transplant into.
The successful outside growers I know start real small, and transplant as needed, or, by a predetermined schedule. Something like this.
Starter cube. after approx. 2 weeks from seed; 4" pot, or a 1 gallon pot. These size pots will allow for optimum root growth, and each time you transplant, you will have used less grow medium and have a stronger plant. When you go to, too big a container at the start; You waste a lot of medium, and end up wasting approx. 1/2 of your soil investment, because the roots grow down before they grow out. Force them to fill your container before transplanting. Then when ready to move outside. your plant will thrive due to a stronger root foundation.