Fall is the best time to test soil. UGA Extension calls it the most desirable window, since lawns and garden beds are dry and easy to walk on by then. Fall also hands lime the 2 to 3 months it needs to react. Spread lime the same week your seedlings go in and it has had none of that time. Your roots then grow in ground sitting at the pH you started with, not the one your report told you to aim for.
Dry ground matters more than it sounds. Wet soil sticks to the probe and packs into the core, so you send in a sample that is half mud. It is no fun to walk on either, and you end up pulling a couple of cores near the path instead of spreading them across the whole bed. Fall soil crumbles off the probe. You cover the area in one pass, and what goes in the bag stands for the whole bed rather than one damp corner of it.
There is a second reason to test soil in fall, and the weather has nothing to do with it. The lab needs its own time. Analysis runs 2 to 3 working days, and your report lands 4 to 6 days after the sample arrives. In April that wait eats straight into planting week. In October it costs you nothing at all, because you still have the whole winter to buy lime, spread it, and let the ground do the slow part.
Early Fall
Pull your cores once the beds dry out, then mail the sample while the lab is quiet.
Late Fall
Your report arrives in 4 to 6 days. Spread the lime it calls for and mix it into the soil.
Winter
The lime you mixed in works on the soil through the cold months and the pH starts to move.
Early Spring
Plant. The lime has had its 2 to 3 months and the numbers on your report now match the ground.
Fall is the default, not the only answer. Sample right away if trouble shows up mid-season. Yellow patches, a bed that stalls out in June, one corner of the lawn that thins while the rest holds. Waiting until October to learn the pH was wrong the whole time costs you a full season of growth. A mid-season sample gives you something you can act on now, and it does not stop you from taking your usual fall sample later.
Take your soil test before planting season, and take it at the same point in fall each time you test. Pick a week and keep it. Early October one year and late November the next leaves you with two numbers you cannot line up. Nutrient levels drift as crops pull from the ground and rain moves things around. Matching the timing turns a folder of old reports into a trend you can read.
Your last report still earns its keep while you wait on the new one. Prior-year results can guide your fertilizer choices until fresh numbers arrive, so a sample that goes out late is never a reason to skip feeding a bed. And the schedule after that is short: retest vegetable beds every 1 to 2 years, lawns and ornamental beds every 2 to 3 years, once fertility sits where you want it.
So pick a weekend in fall and make it the sampling weekend. Mine is the one where the last tomato plants come out. The bag goes in the mail that Monday, the report is back inside a week, and the lime goes down with months to spare before anything gets planted.
Read the full article: Soil Test Kit: What It Gets Right and Wrong
