For seeds that require "cold stratification," lately I've been wintersowing them... I think the freeze/thaw action over the winter months takes care of cracking the seed covering a bit, no need to nick. It might not get cold enough in your zone for that, but you could always cold stratify by putting them in a baggie with a little moist perlite, then into the fridge or freezer.
I think we probably need to distinguish between seeds that need to be nicked & soaked and those that require the low temperatures of actual cold stratification to germinate... I seem to recall that there are some very tender perennials that need to be nicked (passiflora, perhaps? now of course I can't remember where I was reading about it), and those probably wouldn't appreciate cold temperatures.
What seeds do you have better success with if you nick them? I know I got no sign of germination on a prized seed of Vigna caracalla until I dug it out of its pot, nicked it, re-soaked it, and replanted it. I've also nicked four o'clock seeds with good results...
Trying to think of other seeds with hard outer coverings that might benefit... does anybody nick morning glory seeds? I don't think I want to try to knick a big handful that I might be sowing all along a fence line, but I'd be willing to do it with a few special japanese morning glory seeds if it would improve germination success... ?
It talks about internal and external dormancy of seeds and some seeds that need scarifying or stratifying.
I've scarified some holly seeds by laying them in the driveway and rubbing my boots on them...
get a clean small jar with a lid(I've used a large baby food jar),cut a piece of course sandpaper to fit jar,roll the sandpaper into tube w/rough side facing in,insert into jar,toss in seeds,put the lid on and shake for a few seconds to a minute depending on how hard seeds coat is.
Thanks, claypa -- I knew there was a problem with our terminology in there somewhere!
P, that's a great idea... I'd heard about using sandpaper and applying it to individual seeds, but your way makes a lot more sense! I think most seeds with hard coats don't need a big chunk taken out of their outer "shell," just a little weak spot for some water to get in and for roots to break out.
I've tried a variety of methods to nick canna seed. They are tough little things, and in the process of trying to nick them I have split some in half (I'm not even sure how) and sent others flying across the room (trying to hold them still with pliers and scuff them good with a metal file...)
I conducted an experiment with mine this year in terms of a variety of pre-wintersowing techniques:
I nicked some (finally with some success with toenail clippers -- though some did still go across the room),
soaked some without nicking,
and planted some without either.
So far the nicked but not soaked seeds are the only ones to germinate -- and that at a very small ratio. I wintersowed them in mid-January here in zone 7b, and noticed the first germination around Feb. 24.
I am a complete novice with canna seeds, so I may be approaching this all wrong...
to scarify really hard seeds like lotus, I use a pair of pliers to hold the seed and then use the sharp edge of a triangular file found in the woodworking tools department. Otherwise my fingers get in the way.
It's really too hot in Mexico City for Sugar Maple. Do you live in the mountains?
If your seeds are dry you will need to give them a moist, cold treatment before sowing them. Soak them until they swell a bit. Scratch some up and leave some unscratched. Then put them in a SLIGHTLY moist, sterile medium (perlite/peat moss/...) and keep them at around 36 to 40 degrees F for two to three months in an airtight bag/container. It would help if you give them a shake every few weeks.
I would put some for two months and leave some for three to have a shot both ways. A seeds dormancy really depends on where it was collected.
I am trying to grown bird of paradise seeds. I filed two of them a bit with a nail file and soaked them overnight before planting. I gently dug them up a week or so ago and nothing appears to be happening. I planted them around the beginning of March. I have 3 seeds left and would really like at least ONE of them to germinate and grow for me. Anyone have any ideas? Thanks!
Here is what my germination chart says: Do not chip or mark the seedcoat at all, but merely remove the orange tuft and soak up to 2 hours. Sow seeds in moist sand, pressing them into the sand until only a small part of the black seed is visible and grow in a temp of 75 degrees F, in the dark and ensure that the sand always remains moist. From 7 days onward, inspect the container once a week and as soon as any bulges, roots, or shoots are seen, remove the germinated seed and pot it up in half peat and half sand.
The fact that you had to "dig them up" makes me think you may have had them buried too deep. Seeds that need light to germinate can sit there forever and do nothing if you plant them too deep. Some tropicals will also benefit from a heat mat...some won't germinate at all without enough bottom heat, and others will germinate without it but it'll go faster with the heat.
Hard shelled seeds (Asparagus, Cotoneaster, Lupine, Morning Glory, etc.) need some method of softening the seed. That can be done by freezing, scarification, acid bath, H2O2 or a hot water soak. I prefer the hot water.
In this technique, which I use on a lot of seeds, you place the seeds in a cup and pour hot (170 to 200 degrees F) water over them, to a depth of about 5 times their diameter. Do NOT use boiling water, as that will kill the seed embryo. Allow the water to cool and let set over night. The seeds should be plump and on the bottom of the container. I use this method even on seeds that donít absolutely need it these days, because it both speeds germination and raises the germination rate. Seeds that are still floating after 24 hours can be pulled out and retreated.