Topic: Seeds: shade or light for germination

[Nemesia]

I have been gardening for a while but have not had an answer to this question and wonder why the seed producers don't put it on the packets, i.e. when sowing seeds how do I know if they will germinate better in darkness or light. I do know that Impatiens will only germinate in light but that's the only I do know. Do you all tend to grow your seeds in the same way for each?

[flitwickone]

my first year and i sow the seed and whack it in the cold frame


doing ok so far i think

[tim]

http://www.arrowhead-alpines.com/seed.htm covers some things.

[:(]

http://www.arrowhead-alpines.com/seed.htm covers some things.

Not UK and highly overcomplicated?

Its easy, if the packet says exclude light then do it.  If not, dont. they dont expect you to guess and get it wrong because then theyd get lots of complaints about poor germination.

[davyw1]

Most of the seeds we use as gardeners germinate better in the dark, that does not mean just covering them with compost.
Plant your seed and cover with a light dressing of compost (a good guide to how much to cover with is about three time the thickness of the seed). Cover with glass, clear/milky colored polythene to create condensation, then cover with something to extract the light i use black polythene

[Bugloss2009]

Delphiniums were one that was supposed to germinate better in the dark, but a quick Google suggests it's not necessary.
I don't bother doing anything special with small seeds - so long as you keep the surface of the compost moist, like covering the tray with cling film, everything germinates OK

[tim]

Funny that all the old teaching was to cover with brown paper & glass.

[PurpleHeather]

The general rule with all seeds is to cover them so that they are in the dark.Finely sieved soil or light compost kept moist so that the babies can poke through it. Works for most seeds. Peppers, I read, wont germinate in the light.

 A lot of seeds will germinate without the cover but the cover serves as a protection for the seedlings too. Exposed seedings can die off very quickly.

Seed packets do explain if a seed will only germinate under different conditions.  They usually tell you the 'germination period' Some seeds can take weeks to pop up. Rosemary takes six weeks. I have seen packets where it tells you to put the seeds in the fridge

Natures way is for seeds to scatter in autumn and as they lie on the ground they get a dusting of light soil whilst waiting for the warmth of spring sunshine and April showers to come alive.

I often wonder why a seed tray of seeds sown on the same day come through several days appart and can only think that there is a delay mechanism in some seeds so that if the first germination is killed off the next lot come along with a second chance.

[Bugloss2009]

I often wonder why a seed tray of seeds sown on the same day come through several days appart and can only think that there is a delay mechanism in some seeds so that if the first germination is killed off the next lot come along with a second chance.

the everlastting pea Lathyrus latifolius has different seed in the same pod - some will germinate straight away, some after a few months, and some after several years. That's where the making a cut in the seed case comes in

[Robert_Brenchley]

Same with Trillium. If you get really fresh seed (I never have) some will allegedly come up straight off. Otherwise it starts to come up the second spring. You get more coming up each spring, with some taking as much as 5-6 years.

Two years ago I put some parsnip seed in a jar with damp tissue and left it. Some sprouted. Last year, quite a bit more sprouted. Yesterday, I noticed that one more has sprouted. Maybe this is commoner than we think.

Am I right in thinking violas need light to germinate? Do they need any warmth?

[Nemesia]

Many thanks to everybody. A couple of people have said that it tells us on the packet but this is not correct.  If they must have light like Impatiens it is on the packet but in general it just says things like - sow thinly, keep moist, do not cover, cover with fine soil.  As usual, I have done too many seeds  and in my kitchen right now there is a seed tray from a propagator with just one strong seedling in it.I am going to take it out and pot on and then leave the rest to see what happens. Another lesson I have learned is that the propogator gets too hot
so I have lost one tray of seedlings by leaving them on it.
 
I must be doing something right as one pot of mixed salad leaves germinated in a couple of days.

[:(]

Theres confusion here between covering with compost and excluding light. theyre 2 separate things. Most seed packets will tell you how deep to cover the seeds with compost or to leave the seeds uncovered on top of the compost. Putting the seeds in the dark is different. A lot of packets say do not exclude light or cover with clear glass or polythene - ie dont put them in the dark. If the packet doesnt say anything the default is dont put them in the dark. think about what happens in the wild, the seeds fall off the plant and might get some soil on them but they arent subjected to 24 hours of dark.

[davyw1]

Its seed planting time so why not do it both ways one lot in light another in the dark see which germinates first then the issue is sorted.

[dtw]

In nature they aren't shaded.

I don't cover mine and they seem to come up ok.

[jennym]

I was taught that seeds can have very different requirements for germination. My notes say that all seeds require warmth, water, oxygen, warmth, and some seeds require light.
WARMTH - Some seeds contain a hormone called abscisic acid which helps keep the seed from germinating until it reaches the stage where the soil is cold enough to keep it dormant for a period of time, then when the soil temperature increases the seed will start to germinate. This is called stratification (the cold bit) and vernalisation (the warm bit). These are the seeds that sometimes have the "refrigerator" method written on the pack.
WATER - Some seeds have a hard coat which, in nature would pass through the gut of an animal and the stomach acids would help break down the seed coat, or some seeds have their coats broken down by fire. This is called scarification - you can scarify by nicking the seed to break the coat and allow water to enter (this is speeding up the natural process). Some seeds contain phenols which stop the seed from germinating until it has been wetted enough (think these are cactus like seeds).
LIGHT - some seeds have thin coats, mostly these seeds react to light or darkness (not both). Big seeds with thin coats often have different chemicals in them to small seeds with thin coats. Usually, small seeds with thin coats need light to germinate, and big seeds with thin coats need darkness.

Hope this helps - I know there's a lot more to seed germination than this but this is about all I have. Thompson & Morgan do an online guide to seed sowing but it seems to be all flowers. http://www.thompson-morgan.com/seed-sowing.html
I normally just do as others have said - read the packet, most veg are straightforward, and if they aren't the packet usually has clear instructions.

[nilly71]

Peppers, I read, wont germinate in the light.

Mine have, I just used the left over seed from some peppers that were bought from Tesco,( I don't know what they are called but about 5" long and just over 1" thick) nothing special done with them, just scooped out and put in pots with a light sprinkle of soil. Most of them are poking through the soil this morning(yesterday morning ;D)

Neil