Stratication of verbena bonariensis, or any other plant for that matter

I'm told that verbena bonariensis requires, or at least prefers, stratification, even the pack that the seeds came in tells me to put them in the fridge for 2 weeks.

Problem I see is that it's not time to plant them out yet, so can stratification last for up to 2 months instead of 2 weeks? As I see it, the whole concept is to mimic winter -> spring conditions, so based on that I would guess it's fine for as long as necessary.

If placed in my cold shed in a seed tray will they eventually just germinate once it's warm enough and does that count as stratification?

Cheers,
HBK.

 

Yes HBK - you have got it. The easiest way to get success with plants is to copy nature. You can get Verbena to germinate without cold stratification, but its a bit hit and miss that way, and may take a long time.

In the border, Verbena seeds fall to the ground in autumn, and by the following spring you will have lots of seedlings. That's nature's way of doing it. You could do exactly the same and sow the seeds in a tray in autumn, cover it with a piece of glass to keep the rubbish and stray seeds out. Put it outside in the cold and wait till the spring. The seeds will germinate at exactly the same time as their cousins in the border. Stratification, by putting seeds in the fridge, is simply a way of speeding the process up. Consequently the stratification times quoted will be the minimum time needed to convince the seed that a whole winter has passed. The seeds must be damp, as they would be in nature and in the fridge not freezer. As in nature, they won't germinate during the cold spell, but will wait till it warms up, ie when you take them out of the fridge. You could then put them in a heated propagator, and they should germinate quite quickly. Again all you have done is to speed up the process and kid them that spring has arrived.

Leaving them in a cold shed would do exactly the same thing. But without extra heat they will warm up slower and germinate later. When they start to germinate make sure there is enough light for them.

The reason why some plants need cold stratification and some don't is to do with the seed coating. Many seeds have a protective coating, to prevent them germinating at the wrong time. A cold treatment effectively removes this coating thereby allowing the seed to germinate. Other coatings simply disappear with time and so don't need a cold treatment to remove it.

 

I'm surprised its as little as 2 weeks ... seems very short.

Mind you, my T&M Packet says nothing about stratification ... just says to chuck it in the propagator

... and I am confused that 50% of the suppliers that sent me seeds indicate (on things that need stratification) a "period of warm first, then stratification in the Fridge, then Warm again".

The rest just say "stratify in the Fridge, then Warm."

(some suggest repeating the cycle if germination does not occur, but that's per-variety, so probably not relevant to this topic)

So ... I have a dozen on my desk doing the "warming before stratification" but most are in the fridge doing "stratification first"

I wonder if it makes a difference?

 

Thanks a lot Peter. They'll be going into the shed in the next couple of days.
I'm sure they'd do better in the fridge but I never fill it up so I've only got a little fridge.

I'm sure they're just being overly picky Kristen, but let us know if there is a noticeably difference in results.

 

On the recommendation of someone here (Pete I think, but forgotten for sure) I am growing mine in zip-lock bags. Half a piece of kitchen paper folder, and inserted in the bag. Pop the seeds in an "organise" them evenly between the two sides of the folder kitchen paper. Push the kitchen paper sides together (i.e. lower the top-sheet to meet the bottom, so the bag is still open, but both "sides" of the the kitchen paper are together, sandwiching the seed, are are against the bottom side of the bag. Squirt some water in from a spray bottle until the kitchen paper is moist (I've got Chesunt Compound in my spray bottle, some sort of fungicide would be a good idea), stick it in the fridge.

It can stay in the bag when it comes out until it germinates ... cut the kitchen paper out and prick-out kitchen paper and chitted seedling (assuming that there are few enough seeds to go to that amount of trouble ...)

 

Probably PeterS, Kristen.

Not me, I just bung them out in the cold and hope for the best.

 

Me to Pete, bought some from ebay last year, started a dozen off in march and had 100% germination..