Germinating Rubus seed

I have been messing around with Rubus breeding but always have such low germination rates. I play a numbers game, if I plant enough seed I will always get something up. But this isn’t all that efficient.

I have tried growing fresh seeds just mushing the fruit and planting the seeds, I have tried wet cold stratification of fresh seed, I have tried drying the seeds, and nothing seems to give me great results.

Low germination is ok when I have a lot of seed to plant, but when I have small numbers of seed it is kind of heartbreaking.

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Post number 7 on the Breeding Rubus thread deals with this very topic. Apparently, soaking in a sulfuric acid solution for a few minutes should give you good germination if the seeds are viable. Getting viable seed to begin with is the tough part, as they apparently don’t last long once dry (unless frozen).

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What I meant by this is that it took 15 minutes in battery acid for them to germinate. They had to be cold stratified too, and kept moist, for about 90 days. Then they germinated. So first scarification for 15 minutes, then a 90 day cold stratification. I’m not sure 15 minutes is ideal? I averaged 4 plants grew per berry. Maybe it is slightly too long and some seeds were destroyed, or it’s too short, and the coats on most seeds were still intact. I need to do further trials to get the best time. Other friends of mine reported 30 minutes in bleach worked too.
What I did was was once I rinsed off the acid, I put them in seed trays and out in the attached garage where it remains between 25 and 45 degrees all winter. In the spring I put them out in a shaded location to germinate. Last time I had them marked 5, 10, and 15 minutes. 4 plants emerged from the 15 minutes. None from the others. So next time I will do 15, 30, and 45 minutes. Blackberries even have tougher coats, they will need more time than raspberries.
Raspberry seeds need light to germinate. They should be pressed into the surface of the soil, or just a super light sprinkling of soil on top.What I do is put them on top of the soil, and use an object to slightly press them in, like a pane of glass, or whatever.
Bramble seeds are not easy in any way.
Seeds not treated in anyway and left for 2 years, may germinate.
So in the dark of the garage or a refrigerator they will not germinate without light, which is nice really because when I’m ready I just put them out. I don’t have to worry about them sprouting sight unseen. Also keep moist, you’re going to have to mist, or bottom water not to disturb the soil.

The method I use was taught to me by a professional breeder who said a PhD botanist developed the technique. He put the trays in a fridge, I just leave them in the garage. I had to develop my own method with the acid because the professor, and breeder used 90% solution of sulfuric acid. Have you ever seen that stuff? It smokes when you open it, deadly stuff! Instead of tracking it down from a laboratory supplier, I just go to O’Reilly’s and buy some 30% battery acid. If you spill this on your hand you have a few seconds to wash it off before a burn, it is weak… So strain seeds out, You can buy fine meshed strainer that will catch the seeds, rinse acid off them under the tap

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We have a bit of a problem with blackberry weeds around here, it feels like every seed that is eaten by a bird germinates. This has me thinking, would it be possible to increase germination rates of Rubus seed by passing it through the digestive system of a bird rather than battery acid?

I tried with chickens but the seed was too difficult to retrieve. Either the seed was ground to nothing, or I was unable to find them as the volume was too large. The point is that it was not a workable idea.

What about something small like a canary? They live in a cage so retrieval of seed should be simpler. Would some seed be destroyed in their gut or would they mostly pass through unharmed?

I would say yes! I agree birds do a great job. I have a raspberry that will fruit this year from the birds. It grew so much compared to other raspberry seedlings. I named it Robin.
I think a canary would work, but you still need stratification.
You could also just use bleach, rate is 30 minutes, longer with blackberries, maybe 45 minutes. One would have to experiment. Thanks to this discussion and those who provided links to info. I see Tay and Marion are the same ploidy level. That sounds like an excellent cross, and I have both. I will be doing that one. Tayberries fruit very early, Marion is late, so Marion will be the mother. I’ll collect pollen from Tay and save till Marion flowers later in the year. Some don’t like tay, but to me, it is fantastic, with a strawberry like flavor. Very different from either raspberries or blackberries. Marion has a very complex flavor, I would rate Number one for blackberries. It is fantastic, and what I’m looking for. I see a hybrid as being very interesting. No matter what traits it keeps, it should be out of this world. I will keep every possible seedling I can germinate.

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Hi @Drew51 can you please explain why Marion would be the female parent as opposed to using Tayberry?

Out of convenience, you could do it either way. When Marion flowers, tayberries will be done, Not much if any overlap of flowering. So I will collect tayberry pollen and wait for Marion to flower. If their is some overlap, I may do it both ways.

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I have had varying results germinating rubus seeds - it depends on the species - but as they have a hard seed coat, thickness depends on the species. You definitely need to soak in acid (up to 3 hours) then rub on a sieve and soak in bicarb solution. Alternatively, I soak in household bleach solution - this works for R.leucodermis. then cold stratification for three mobths, then warmth. A long process but fascinating.

I am having good success germinating R armeniacus (Armenian/Himalayan blackberry) after cold moist stratification. No fancy scarification (mechanical or chemical) this round. Here’s what I did:

  1. Cleaned the fruit at harvest (pulsed blender) and used a kitchen strainer to remove the pulp. Then I let the seeds soak in tap water for 4 days, changing the water once or twice a day to clean them off and potentially ferment seat coat.
  2. Cool-moist stratify @35-40F in 50/50 peat/perlite for 4 months in ziplock bags. I had a moderate amount of the peat/perlite in each bag with plenty of extra room- you’ll see why next.
  3. Germinate indoors under a few different conditions, all of which worked to some degree. They are ranked here in roughly fastest/highest rate to slowest:
    a) in stratifying ziplock in near-complete darkness @ 68-80F. This was just a cabinet above our kitchen refrigerator.
    b) in stratifying zip lock resting on top of a grow light used for other seedlings (for warmth). Received ambient light, but minimal direct light. I think this was enough cooler to reduce germination relative to the above fridge group & light didn’t make much of a difference.
    c) in traditional garden center seed starting trays with humidity dome. No seed heating mat. Received grow light and south exposure window light. Definitely the slowest & lowest rate.

Were I to do it again, the ziplocks are easy up front and work great. I don’t know if there is anything magic about the peat/perlite. Only challenge with ziplocks is being delicate transferring the seedlings (I used a bamboo skewer). I think the seed trays hold potential, but probably need a heat mat to have decent germination rate. I’m guessing my combined germination rate is going to be about 25%- not great, but quite workable given how many dang seeds you can collect from blackberries.