Nasturtium Seed Scarification Experiment

by Fern on April 4, 2010

in Flowers Galore

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As I mentioned earlier, I am participating in the GROW project, which is sponsored by Renee’s Garden seed company. A group of bloggers are all growing the same plant from seed, Nasturtium ‘Spitfire’ and have all agreed to post about growing that plant on the first Sunday of each month.

I’ve decided to start at the beginning, with sowing the seeds. Nasturtiums have a hard seed coat, and some sources recommend “scarification” to improve germination. Scarification means softening or removing part of the seed coat. I tried five different methods, and had one control group (i.e. no scarification). The purpose of softening or removing part of the seed coat is to allow water into the seed and thus get the germination process started more quickly and with more consistent results.

Unfortunately I didn’t have the foresight to start my little experiment early enough so that I could report on my findings today. But I should have some germination data to report later this week, so look for it in the Grab Bag post on Friday.

Soaking in Hot Water for 24 Hours

For the first group, I boiled water in my teapot and poured it into a cup. I then placed four seeds in the cup of boiling water and set the timer for 24 hours. Pretty easy!

Soaking in Hot Water for 3 Hours

This was a variation on the first method. Boiling water went into the cup along with the seeds, timer set for 3 hours, and away we went.

Soaking in Cold Water for 24 Hours

The third group had an even easier procedure than the first. I simply poured tap water into a cup, dropped the seeds in, and set the timer.

Filing the Seed Coat

Unless this method proves to be more effective than the others, I wouldn’t recommend it. I used a metal file to sand off a small portion of the seed coat. It was difficult to hold the seed firmly while filing it, and it was also hard to tell how much filing was enough without over doing it.

Chipping/Cutting the Seed Coat

For the seeds in this group, I used a nail clippers to chip a small part of the seed coat. It was easy, and quick. Next to no scarification, this would be my preferred method, because you can accomplish it quickly. I’m an instant gratification kind of gal.

Control Group

This group of seeds was not scarified. With any luck, this group will germinate at the same time as the others, or even before them. In which case, I’ll be able to recommend that no scarification is needed and that nasturtium seeds can be sown just as you would other seeds.

* * * * *

I’m growing Nasturtium “Spitfire” for the GROW project. Thanks, to Renee’s Garden for the seeds.

Here are some of the posts from other participants:

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{ 30 comments… read them below or add one }

Bob April 4, 2010 at 10:22 am

It will be interesting to see what happens. I have great success soaking for 24 hours prior to sowing. I use warm water. Boiling water would make me feel like I’m cooking the little embryo
inside the seedcoat. I started
my seeds two weeks ago and have some very happy seedlings right now.


Fern April 4, 2010 at 11:26 am

Bob–I boiled the water because that’s what one of the sources I consulted recommended. I personally have always just used luke warm tap water and had decent results (nasturtiums don’t seed to germinate at the super high levels of other seeds). We shall see what happens later this week!

MrBrownThumb April 4, 2010 at 3:38 pm

This is an awesome idea for a post with the seeds, Fern. I just saw that a blogger was having trouble starting them and some people on Twitter had given her tips on scarifying them to get them started.


cheryl April 4, 2010 at 4:24 pm

I planted “Amazon Jewel” Nasturtiums from Renee’s Garden 2 weeks ago. I never even thought about scarifying! They all came up in about 10 days and are almost 2″ tall already.


Angela Davis April 4, 2010 at 8:39 pm

Fern, I read your post this morning but came back to comment. I think Mr. Brown Thumb is talking about me since I’m having issues germinating my seeds. This is our first year starting our veggie seeds indoors so I picked up all the fancy gadgets. I have a heat pad, seed starter mix, plastic tray/cover and a grow light. My nasturtium seeds just laughed in my face & refused to germinate! With my next batch I’m soaking and scoring the seeds (keep your fingers crossed). I can’t wait to see how your experiment turns out.


Fern April 4, 2010 at 8:58 pm

Cheryl–Good to know that you had a good (100%) germination rate without doing anything fancy. Nasturtiums have always been kind of finicky germinators for me, so we’ll see how my experiment goes. Maybe I just wasn’t using fresh enough seed in years past.

Angela–I think scoring and soaking will work out well. I’ll keep my fingers crossed for you, if you’ll keep your fingers crossed for me! :-)

Mr. Brown Thumb–Hopefully it will provide some good info about what works best!


Claire Splan April 4, 2010 at 10:09 pm

For filing, I usually find it works best to just rub the seeds between two sheets of sandpaper. But I always soak them afterward too.


Fern April 4, 2010 at 11:43 pm

Claire–How do you do that without the seeds rolling all over the place?

Monica the Garden Faerie April 5, 2010 at 5:28 am

Hi Fern, I don’t think Nasturtium require scarification… I sowed mine fairly late for winter sowing and they came up without my knicking the seed coat. Normally, I winter sow in Jan and Feb, so things that need scarification have long enough to moisten up on their own int he seed mix (and I don’t have to do anything extra). You know, I’m lazy.

You asked what seed swap site I used–and I didn’t use any. I hosted two snail-mail seed swaps through my blog: http://gardenfaerie.blogspot.com/2009/12/seed-swap-starting-soon.html.


Fern April 5, 2010 at 9:27 am

Monica–I’m too impatient to wait that long! ;-) I want my seeds to germinate in less than 2 weeks. I’ve had inconsistent results without scarification, as have some other bloggers taking part in the GROW Project.

Monica the Garden Faerie April 5, 2010 at 5:29 am

P.S. You could also rub the seeds on sandpaper, if you wanted.


Matti April 5, 2010 at 6:57 am

Super cool. I have to check this out. I bet you should have some good success with both groups…but time will only tell. Matti


Gardenmom29 April 5, 2010 at 8:35 am

I don’t think I soaked or used scarification with any of my nasturtiums in the past…and they germinated very easily (within 10 days or so). But I am very curious to see how your experiment turns out. I thought maybe this time I would soak mine…


Mary C. April 5, 2010 at 9:15 am

I started some nasturtiums for a friend of mine. The packet had only 6 seeds, I soaked them all about 24 hours in water straight from the tap, and sowed each in a separate cup. Four of them sprouted, three flourished and the fourth is a bit of a runt (but I’m rooting for him!). That was about 2 or 3 months ago… I’d need to look at my calendar.

I’m so happy, just after you posted that you’d be doing this project my dad said I could expand my container gardening area! I cant mix more flowers into my veggie containers! I picked up Alaska and Tall Single nasturtiums this weekend and they’re soaking right now. I’m now really anxious to see how your seeds do so mine will grow well too! Thanks Fern :)


TC April 5, 2010 at 10:02 am

Good experiment Ms. Fern. I/we didn’t have any trouble getting our seeds to germinate without scaring or soaking. As a matter of fact, I was really astounded at how quickly they sprouted – right at six days.


Diane April 5, 2010 at 10:23 am

Interesting experiment! My wintersown seeds came up in 20 days without scarification but I was content to wait for them. I find the thought of putting seeds in boiling water pretty scary – it will be fun to see if they all come up!


BrownThumbMama April 5, 2010 at 11:52 am

I’m interested to see your results. I had a few enthusiastic seeds and some that just plain stayed asleep. When you find out the best method, I’ll start the rest of my nasties that way!


shari April 5, 2010 at 3:39 pm

This would make a really great LOTB reader survey, Fern. I’d be really interested in seeing a large sample of people starting the same type of seed in various manners and knowing what sort of germination rates people get. I will be following your experiment with great interest!


Jan Dear April 5, 2010 at 4:11 pm

This really is an amazing site! I love the internet! I just came in from planting my seeds, all 180 of them or so, and then I thought I should try to find info on how to germinate and look what I find. People at my pottery guild all say they have no luck except for my instructor, who just throws them in the ground and they sprout like wild fire. (My husband just asked me why so many seeds, & I said I’m giving lots away)!


linda April 5, 2010 at 6:36 pm

I was wondering about this! I’ve never grown nasturtiums before, but I was a little surprised the seed packet didn’t recommend scarification. I went ahead and just planted mine without any treatment. If they don’t sprout I’ll try soaking. I’m interested to see how your experiment turns out. Experimenting is, to me, at least half the fun of gardening.


Adriana @ Anarchy in the Garden April 5, 2010 at 10:05 pm

I direct sowed them y voila! They’ve self sowed since and I have several cascading plants intermixed with vegetables.


Tamara April 6, 2010 at 2:35 pm

We’ve never grown nasturtium in our greenhouse but I’m guessing it may have something to do with the difficulty in germination :) There MUST be an easier way…..how do the BIG growers do it?

Have fun with the experiment and hope you get lots of great blooms!


carrie August 21, 2011 at 11:56 am

Shall I sun dry seed pods in a tray from this summer’s nasturtiums then save, or toss in the garden at the end of summer?I have so many green seed pods. can’t eatem all.


Joan S September 5, 2011 at 8:02 pm

I have the same question. Do I dry the green seedpods before planting next spring?


Fern September 5, 2011 at 10:40 pm

If you collect them now, they will dry by next year. It’s hard to wait until the seeds are brown on the plant, because by then, they almost always fall off. It’s best to wait until they are large and still green, and pick them and let them dry while waiting to be planted next spring.

Ron B February 25, 2012 at 11:19 am

I find the easiest way to germinate Nasturtum Seeds is to place a few sheets of paper towel on top of a large Pizza pan , then place all your seeds on the paper and cover with a couple of more sheets like a blanket. Then Just keep it moist and check on them every couple of days. After I see them sprouting I simply transplant them into soil containers and away they grow !


Felicia March 26, 2012 at 5:13 am

I’d love to know the results of your experiment!


Lisa April 4, 2012 at 4:45 am

I’ve done a lot of gardening, but never grown nasturtiums until this year. I was surprised when only 2 of the 6 seeds I planted germinated. I think I will try soaking the seeds first.
My plan is to use nasturtiums to attract aphids and spare my tomato plants. Then when one of the nasturtiums is infected with aphids, pull the entire plant, bag and seal it, and dispose.
Has anyone tried this before?


cheri raye April 28, 2012 at 4:14 pm

I always see these wayyyy after the fact, but i always have an opinion, on just about anything, so here goes,
I never do anything with nasturtiums, they are hard but not like the orchid tree seeds, or Mexican bird of paradise…which with those i burn the edge, until they pop then plant and they always sprout.
Thanks for the opportunity to voice my opinion!


MiNotu September 2, 2012 at 1:57 pm

Well… what happened??!!!


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