Hello 
For the previous three seasons I’ve grown white widow from seed without issue. This season I’ve switched to Bruce Banner and have had three of my seedlings fail due to helmet head. I ‘cracked’ the seeds by letting them sit in a moist paper towel for 48+ hours before placing in soil. They each had substantial root growth before being placed into soil. I tried to keep the soil nice and moist. When I eventually went to assist with the helmet head, the shell just falls off and the cotyledons inside appear mushy. What am I doing wrong? I know the seed shell must be moist in order for the seedling to be able to work it off, but it seems like its too moist and its causing rot inside? Any help is appreciated!
This isn’t too uncommon. Either a strong shell or possible dryer climate can hinder development.
Sometimes a drop of distilled water will help keep enough moisture for the shell to stay soft and the plant work it’s way out. You can also take tweezers and gently squeeze on the seemed sides of the shells to force them open a little more. I’ve had the helmets come off, but not the membrane and had to actually cut it open with surgical scissors lol.
Edit… I started typing before reading it all. I would try, if you have a real steady hand to snip the membrane. If the cotes are still mushy after the shell falls off, the membrane between it and the cotes may not be opening like it should.
Ive cut mine off with a new razor blade. I usually give the helmet a day or two to dry out. Medium looks really wet. If you let them dry out a bit the loss of moisture will force contraction and they come off a lot easier. I use coco pods and let them dry to point of color change before watering. Once a seed has soaked it has enough moisture to last 3-4 days in my observation.
This happens a lot with pregerminated seeds and is often because they are placed in media with tap root down and then just extend straight up when sprouting. If you place tap root up the husk is usually peeled in the process of sprouting.
I always like to point out that hygiene is critical at this point too. Use sterile gloves or tools when handling seeds.
Thank you all for your responses and the info. I definitely placed them in the soil with the root down after sprouting, your illustration makes a lot of sense! I’ll make this adjustment with the next ones. Thanks again for your help!
I’m pretty lit but I believe he is saying root up not down 
To high and read that wrong, disregard 
This should be tagged as a “solution”.
Well said Mister @dbrn32 
No problem. Don’t purposely let the taproot get long either. If you see it has emerged from the husk is plenty good. I use paper towel method and they will start to grow into the paper towel risking damage when separated.
I put them in soil as soon as I see the tiniest bit of white root showing.
The only reason I wait that long is to ensure that I am not wasting time on a seed that won’t germinate.
They stay moist enough long enough?
@StonedCold13 yes, when put into a ziplock, close and put in dark space or wrap in aluminum foil for darkness. I start in Feb so on a seedling starter heated mat. I usually do all difference strain so I first label the filter with Sharpie 1-6 and keep track of which is which.
If the cotyledons are mushy your soil is too wet. I stopped using the paper towel method and cut the soak down to 2 hours. I keep the soil damp but not wet and put the seed down nearly an inch. I put a dome over the cup until they sprout then remove it. Ive had a nearly 100% success rate over the last few years doing it this way.
I do it the same way @plumbdand always works out for me unless the seed is just a dud…it happens