Best Time # 1
Can I lime my vegetable and herb garden in early July to improve the ground for fall or should I wait until mid August when the heat subsides to avoid damaging or causing stress to the current crops?
Charles County Maryland soil and fertility issues
The first thing we recommend is a soil test to check your pH and see if any adjustments are needed for the particular types of crops you want to grow. If you do need to raise the pH, then you can amend the soil in late summer/fall to prepare for next season's crops.
If you already have had a soil test and know the pH is too low for certain vegetables (e.g., if you've had blossom end rot in tomatoes), then you can apply gypsum into the top one inch of soil around the base of the plant. Gypsum is faster acting than lime. But again, this is only recommended if you have had previous problems with blossom end rot and know the pH is too low.
At the following link, you will find information on how to do a soil test and a list of regional labs where you can send a sample.