By KARA HAMMES, guest columnist
As any home gardener knows, it can take a few years after moving to a new house to really get to “know” your site, sun levels, soil conditions, plant types present, and any recurring pest and disease issues.
We are coming up on our third autumn since moving to Brown County, and I finally feel like I understand what I have to work with in our existing landscaping and where I want to go with my overall planting and gardening plan.
One of my biggest realizations this year has been that I can no longer blame much of poor plant performance I’ve been seeing on “too little sun.” With observation of my own site and conversations with other area home gardeners, it was clear I needed to get serious about troubleshooting my soil and nutrient levels.
The first step in that journey was to complete a soil analysis on my different planting areas. All in all, I ended up submitting five separate samples for testing. While the results I got back were surprising in some ways, they also made sense given what I’ve been seeing for past few growing seasons.
Namely, an extremely high pH, ranging from 7.6 to 8.1 in my samples could explain many of my planting issues, since a higher pH affects a plant’s ability to uptake and use nutrients in the soil. Although there are some exceptions, most plants prefer a pH between 6.0 and 7.0. In retrospect, I now realize that pH levels tend to be higher near gravel roads or house foundations and sidewalks, since the limestone dust raises soil pH, which is exactly how most of my landscape beds are situated.
Having an understanding of my soil’s pH level — along with the levels of other necessary nutrients like phosphorus, potassium, magnesium, and calcium — has given me some clear parameters and a plan for moving forward. While I will likely use some soil amendments and fertilizers, I’m also thinking about how to work with my existing soil conditions by choosing plants that naturally tolerate higher pH conditions.
If you’re in the same situation as I was, wondering what you need to do to make your plants look and produce their best, I’d recommend starting with a soil test. And when you do, here are some helpful tips for collecting a good sample and ensuring accurate results:
1. Gather the right tools
Before you can collect any samples, you’ll need to get your tools together, including: a soil probe or sharp spade; a small trowel to break up clumps of soil; a plastic bucket for holding the soil and mixing subsamples; sample submission sheet; and a sample bag (or sandwich bag if you’re a homeowner submitting less than 10 samples) to deliver your sample. Gloves are recommended, but optional.
Soil probes are available to borrow at the Purdue Extension Brown County office, where you can also pick up free sample bags and sample submission sheets.
2. Collect a random sample
Draw a rough diagram of the area(s) to be sampled and determine how many separate samples you will collect. It is best to split different growing areas — such as sunny vs shady, wet vs. dry areas, and different planting types (e.g. lawn, vegetables, shrubs, flowers) — into separate zones for sampling. Collect a minimum of five sub-samples per zone, using an “M” or zig-zag shape to ensure random sampling.
3. Submit enough soil for testing
Clear away any surface plant or organic matter before collecting a sample. If possible, you should collect two or more cups of soil to combine in your bucket. For most testing, one cup of soil is sufficient, but it’s better to have two cups to ensure accurate results. Once each subsample is collected, remove any rocks, large root sections, or other organic matter from the mixed sample in the bucket, before placing your final sample in the sample bag.
4. Plan ahead
Fall is a great time for soil testing because there’s time to add amendments and make adjustments before spring planting. Soil testing and amendments can also be done in spring, but certain measurements (i.e. pH) take months to display any change.
It takes seven to 10 business days from shipping the sample to getting results. Be sure to submit soil samples in advance if you are planning to work your garden on a certain day.
5. Ask questions
A soil analysis page and determining next steps may be difficult to understand. The lab that completes your testing is available to answer questions, or you can always contact us at the Purdue Extension Brown County office, [email protected] or 812-988-5495.
You may also want to refer to the Purdue Extension publication HO-71 “Collecting Soil Samples for Testing.”
Kara Hammes is the Brown County Purdue Extension educator for Health & Human Sciences and Agriculture & Natural Resources. She can be reached at 812-988-5495 or [email protected].
