So, more on reading seed packets! Occasionally, you’ll find that a seed packet calls for some sort of pre-treatment of the seeds. We’re going to talk about what those things mean and how to do them.
The good news is that the overwhelming majority (if not all) of commonly grown garden plants don’t require any pre-treatment of the seeds. Many gardeners never run into seeds that require any kind of pre-treatment whatsoever. Also, if your seed packet doesn’t specify any pre-treatments, then none are necessary!
It’s really only when you start getting into growing some of the more obscure things out there, especially growing perennials from seed, that you’ll start to see it more frequently.
The typical end-goal with any pre-treatment is to simulate what the seed would experience in nature. From experiencing a winter season to getting eaten (and pooped!) by a bird, pre-treatments help the seed experience what it normally would in a natural environment. These are three methods we’ve had to use, in the order of frequency that we’ve used them.
Pre-soaking is the process of soaking your seeds in water. This is often done with certain seeds to help break down the seed’s outer shell and speed up germination. It sort of simulates rainfall and a seed being trapped in wet soils. The process is most often conducted for 12 to 24 hours using room temperature water.
Cold stratification is the process of exposing the seeds to cold temperatures. This is commonly seen in hardy perennials, where the seeds would be exposed to winter conditions. Usually the seed packet will say refrigerate or freeze, to clarify what you need to do. If not, refrigeration is implied. The length of time to stratify the seeds varies per variety and is not extremely precise, it can be days to weeks. Just toss the seeds in your fridge or freezer for roughly the amount of time called for on the packet.
Scarification is the process of scoring your seeds to aid the plant in cracking the outer shell of the seed. This is often seen with particularly “tough” seeds and some people do practice it with squash. (We don’t do it with squash, FWIW.) Lots of ways to get there, like a butter knife or the “hook part” of finger nail clippers also works. Simply score the seed once or a few times until you have a slight gash. You don’t need to go too crazy with it and you’re not trying to crack the seed in half. You can also use sandpaper to thin the outer shell as an alternative.
There are some other pre-treatments, but after 25+ years of growing, these are the only ones we’ve ever used. (e.g. they’re for hot climates) So, if you do run into a seed packet that calls for some seed treatment, this is how you deal with them!
