By: Ilana Goldowitz Jimenez, Plant Scientist & Writer
You may have heard that nicking plant seeds before attempting to germinate them is a good idea. In fact, some seeds do need to be nicked in order to germinate. Other seeds don’t absolutely require it, but nicking will encourage the seeds to germinate more reliably. It’s important to know how to nick flower seeds as well as other plant seeds before starting your garden.
So, why should you nick seed coats? Nicking seeds before planting helps the seeds absorb water, which signals the plant embryo inside to begin the germination process. Nicking plant seeds and then soaking them in water will jump-start germination and get your garden growing faster. This technique is also known as scarification.
Which seeds need to be nicked? Seeds with an impermeable (waterproof) seed coat can benefit the most from nicking. Large or hard seeds like those of beans, okra, and nasturtium often require scarification for optimal germination. Most plants in the tomato and morning glory families also have impermeable seed coats and will germinate better after scarification.
Seeds that have a low germination rate or that are scarce should also be carefully nicked to increase the chances that you’ll get them to sprout.
You can nick seeds with the edge of a nail clipper, a nail file, or a knife, or you can sand through the seed coat with a bit of sandpaper.
Make as shallow a cut as possible on the seed, just deep enough to allow water to penetrate the seed coat. Be careful to avoid damaging the plant embryo inside the seed – you want to cut just through the seed coat while leaving the plant embryo and other structures within the seed unharmed.
Many seeds have a hilum, a scar left where the seed was attached to the ovary inside the fruit. The hilum is easy to find on beans and peas. For example, the “eye” of a black-eyed pea is the hilum. Because the bean embryo is attached just under the hilum, it is best to nick the seed opposite this point to avoid causing damage.
After nicking, it is a good idea to soak the seeds for a few hours or overnight. Then, get them planted right away. Scarified seeds shouldn’t be stored because they can quickly lose the ability to germinate.
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Transfer the seedlings with a pair of tweezers into small pots with a potting mix designed for cultivating Roses.
*If you prefer not to use stratification, highly discouraged in the opinion of Greenhouse Fanatics .
There are several perennial and native seed varieties need to be manually broken from dormancy in order to sprout and thrive in your garden. If you’re planting native seeds and aren’t sure, chances are you should at least scarify and soak your seeds before planting.
Common varieties that require cold stratification for spring planting:
Although this is a comprehensive list of the most common varieties, there are other seeds that do require cold stratification before spring planting. It’s best to call us at (877) 309-7333 if you aren’t sure.
Most of the materials you need to cold stratify seeds can be found in your home or tool shed.
When we first looked into starting lupine seeds early, we found many different suggestions online. Some folks pointed toward chilling them, some toward soaking them, some said to scratch the seed coat with sand paper, others suggested using a nail clipper.
What I really wanted was for someone to just point me in a singular right direction. Was there one method or combination of methods that just worked better? There had to be, but I couldn't easily find any measurable data.
So, I began our first trial in earnest. I picked lupine for a couple reasons.
1. I had saved some of my own seeds, so I didn't feel like I might be "wasting" seeds I'd spent money on. And- I had a lot of them- so I had a large sample size (hundreds of seeds) to test different techniques on.
2. I also had some lupine seeds that I'd purchased. I wanted to know the difference between the specialty seeds and my own. Would my own seeds hold up to the ones I bought?
To start, I listed all of the suggestions I'd found online for starting lupine. Most suggested some kind of scarification, or the chipping off of a part of the seed coat (often with nail clippers). But, as a beginning flower farmer, I had no idea what that meant or how to do it. Others suggested chilling the seeds or soaking them for 24 hours before sowing them.
So I tried all of these things and more and tried them in different combinations. I also froze some seeds, because some people suggest that perennials do best when they have experienced a temperature/climate dormancy period similar to nature.
What I found was that there is really only one way I'd recommend preparing lupine seeds for sowing during the pre-season. My most successful combination of techniques (by far-- like 100% germination far) involved scarification with a small, serrated knife, followed by 10 days between damp paper towels in the refrigerator.
Chipping off a portion of a seed coat with a knife might sound dangerous- and maybe it was, but I came away unscathed. What I noticed was that the seeds that were "aggressively" chipped did best. Here is what mine looked like after chipping, but before chilling. The ones on the left were some of the "aggressively" chipped ones. The ones are the right are un-chipped.
Lupine seeds: pre-chipped on the left and un-chipped on the right
I was initially worried that in exposing part of the vulnerable insides of the seeds I'd ruin them. But, what really seemed to happen was that in opening a "doorway" to the seed, I allowed water to get in. The seeds swelled and all of them had sprouted by the time I checked on them 10 days later.
10-day lupine germination photo
Lupine sprouts: chipped and put in the fridge between damp paper towels for 14 days. I forgot this batch in the fridge - some of them had already shed their seed coats by day 14. They planted out fine into soil blocks.
All said, I'm pleased with the outcomes. Lupine have a tough seed coat for surviving difficult winters, but that can make them hard to sow with good results in the greenhouse. The seed packets said to expect 14-28 days for germination, so I was happily surprised to see ours sprout in less than 10 days. Because lupine appreciate cooler temps, I'm keeping them closer to the floor in the greenhouse (between 50F and 65F), and I make sure they are uncovered during the day so they don't dampen off. Our new challenge with these plants is to keep them going until spring. With the January 1 start day, they will be the "oldest" plants from seed for the upcoming season. We'll have to see how many make it into the ground on the farm.
Thanks for following the Barn Bulletin. Please share a comment if you have a question or let us know if there is a particular topic you'd like us to write about in the future. Have your own favorite way to start lupine? Let us know what works for you!