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Article: Seeds: To cover or not to cover?

Seeds: To cover or not to cover?

When I first started growing from seed I really didn't pay much attention to what sort of covering they needed, and my germination rates were all over the place, sometimes fluking it and others not so much. But as soon as I started researching and giving each species of seed what they required my germination rates started greatly improving! 
Some species are very particular about needing light or darkness to germinate and others are totally not phased and will germinate any which way.
When covering seeds I just use either:
Vermiculite is an expanded natural mineral that is fantastic at retaining moisture, while also still letting some light through.
Seed Raising Mix
Either the exact same mix as they're being sown into, but
dry/damp or the mix with extra vermiculite added to keep the mix a fraction lighter for the seedlings to push through.
The general rule of thumb is to cover seeds about twice the depth of the seeds diameter, which in most cases is pretty accurate, but I like to break most seeds down to these five group in terms of their covering preferences (all our seed packets use these groupings).


All our seed packets come with one of these five covering recommendations:

Needs Darkness

These seeds need darkness to germinate. Cover thoroughly with soil mix and these trays can be stored out of direct sunlight - pop them at the bottom of your shelves and forget about them until it’s close to their germination time.

I even from time to time use a little bit of cardboard on top of the tray to make sure it's extra dark which also does help hold moisture in when it's warmer (just make sure you keep an eye on them daily to remove it at first sign of life).



These seeds are the least fussy, cover with soil or vermiculite, they’ll even often germinate with no cover. We often use a mix of our dry soil mix & vermiculite, for a best of everything mix.


With Vermiculite

Light does help aid the germination of these seeds. They’re generally larger seeds, so a good cover of vermiculite helps hold them down as they germinate – they can sometimes leap out of their cells otherwise.

Scabiosa seeds are notorious for this, so a good heavy covering of vermiculite lets just enough light through to help aid their germination whilst still holding them down enough to not push out of their cells as their germinate.



With Vermiculite

Light aids their germination, so just a light dusting of vermiculite is needed to help keep them moist without fully covering them.

*Our packets may alternatively say to Cover Lightly or Lightly Cover - dust with vermiculite.


Needs Light

These seeds are light lovers. Light is needed for these seeds to germinate. You can very carefully, very lightly dust with vermiculite to help improve the moisture retention, but do not fully cover the seeds or they will not germinate.

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