How to Test Leftover Seeds

| 1/27/2015 9:45:00 AM

Those of us who plant our gardens from seed nearly always have a stockpile of seeds from previous seasons. About this time each year we ask ourselves, “Should I use the seeds I have on hand, or buy new ones?” Tempting as it may be to use last year’s seeds, they are not free. There is a cost in time and effort that comes with planting seeds that fail. At the very least, last year’s seeds can throw you off schedule if they aren’t viable. The simple reality is that you don’t know if your seeds will perform at an acceptable level unless you test them. You can’t tell by looking at them, and you can’t tell by the date on the packet. There are too many variables in the way seeds respond to storage conditions and how long certain varieties remain viable. You need to test.

Testing seeds is easy and inexpensive. All you need are some petri dishes, litmus paper, a pair of tweezers and your seeds. A medicine dropper also comes in handy. If you can’t find them locally, petri dishes and litmus paper can be ordered online from Indigo Instruments.

Carefully distribute your seeds over the litmus paper. 

In order to get an accurate test you need a sufficient sample of seeds. 25 will do. If you have fewer than 25 seeds, you need to test enough of whatever you have to get a meaningful result, at least 10. You simply put the litmus paper in the petri dish, and then place the seeds one by one on the dry paper with your tweezers so they are separated from one another (this makes counting easier later on). Once your seeds are distributed over the paper, carefully drop water in different spots until the moisture spreads throughout the litmus paper. You want it moist but not saturated. Too much water will make the seeds rot. Start with a few drops to see how they spread. Add more if the paper is dry.

Cover, label and date your seed sample. 

When you finish these steps, put the lid on the petri dish and affix a label that includes the seed type, number of seeds, and today’s date. When you’ve done this with all the seeds you wish to test, put them in a low traffic location out of direct light where the air temperature is comfortable. A shelf in your kitchen, pantry or office will do.

2/6/2018 11:35:26 AM

David, Thanks for mentioning Indigo Instruments in your post regarding petri dishes, etc. Small favor if you can indulge me. We recently sold our 24 year old domain, & now use Would it be possible to change the link to the new domain? Much appreciated.

2/6/2018 11:35:25 AM

Thanks for the Indigo Instruments mention for petri dishes, etc. Small favor...we recently sold our domain name Could you change the link to Much appreciated.

1/28/2015 4:11:54 PM

Well this applies especially if you're dealing with potatoes. As we know buying spuds should only be a one-time investment. You would have to chit the sprouts and make sure they are worthy for the next season. Good read, very detailed and informative. Keep the good work! Best regards.

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