Germinating plum seeds

Hi all,

Silly question here, I gathered plums last year from good trees, 1 yellow variety (probably reine claude) and one blue one (probably a damson plum). I also collected apple seeds. I cold stratified them all in sand in the fridge and planted them like two months ago in a big container with potting soil. All the apples sprouted nicely but the none of the plums are sprouting. What am I doing wrong? It's July already so shouldn't they be sprouting?

I cold stratify outside. That gives the seeds the type of environmental conditions that they need to sprout. I don't have any reason to believe that putting seeds in a refrigerator reliably provides what the plants need.

When I plant nut seeds, like plums, it's common for them to germinate after the second winter.

I don't worry about stratifying seeds in the prunus family, just making sure the the ones that fall and I miss picking up don't become weeds.
The one that are most sure to sprout are the ones that make it into the worm compost.

If you crack the pit open and remove the seed inside you'll get way better germination rates, but seeds are more prone to rottimg. Soaking the whole pit in water for a day or so before cold stratifying increases your germination as well.

I plant most all tree seeds, plums, peaches, walnuts, apples, pears and so on pretty much when I get them. Generally that's in summer or fall as soon as I find them like with walnuts or as soon as removed from the fruit. I directly plant in the spot I want a tree and cover them up with a big rock or old board or something. Next spring while it is still frosting in the mornings I remove the cover. Works a charm for the most part but it isn't uncommon for some to just lay there and sprout the second spring.

One early fall I went to the "used food" department of a big grocery. That's what I call where they put all the past prime produce at reduced price and bought a whole bunch of apples, pears, plums and peaches. I planted them all like that and had more trees than I knew what to do with. Now I do that about every year and sell a lot of them.

Apples and pears are an exception to the rule that some wait till the second year, they always sprout the first year and they spout early, while it's still freezing so need to remove the cover earlier for them.

Grapes are more erratic, sometimes they will sprout in the fall if not covered and sometimes lay there for two or three years, in general they are more difficult so I just plant more of them.

I keep mine in damp vermiculite in the refrigerator and I leave them until they sprout in there before I plant them.

I'm zone 3 with long winters and have had good success with drying apple and pear seeds in the fall then starting to stratify in the fridge in February.

I'm struggling to come up with a plan for plum, cherry and walnut. The cherries are ripe now. I'll either put them in moist sand in my basement til Feb and then into the fridge. Or I'll put them in moist sand in a container and bury it outside this summer. I'm concerned about mold with both approaches. I like growing in air prune boxes instead of nursery beds, which is the only reason I'm not jumping on Mark's suggestion. I can't plant them in boxes now because they'd freeze too hard in the winter.

I sowed peach, apricot and cherry seeds a couple of years ago. First I put them in pots of damp soil for the winter, giving them a winter a little less cold than we have outdoors here. Then in early spring I sowed them all out into a garden bed. Some of them were already starting to germinate.

Lots of apricot and peach seeds germinated, more than I need for trees. But not a single cherry germinated. I don't know why. The apricots were all local; the peaches and cherries were a mix of local (unyummy varieties) and from (yummy) fruit from the US and from Kashmir which is the neighboring region to here, with a different climate.

I did not crack or nick the shells, and the apricots and peaches just did their thing and germinated.

Dear all , thanks for all the advice. I suppose I might need to wait another winter then, and I will also try to grow them outside in the soil.

Someone said that cold stratifying in the fridge seems silly, but for example Martin Crawford says he does that because were he lives (south-west England) the winters just aren't reliably cold anymore for stratification to work properly; it's a controlled environment.

We plant a lot of cherries (sandcherry, nanking cherry and others) and plums every year. Most of the cherry varieties are used as rootstocks for plums and apricots. In August I collect the new seed and dry it and then put them in ziploc bags in the fridge. Then in January I will take the seeds and soak them for 24 hours before putting them in another ziploc bag containing a slightly moist stratification medium. I have tried using clean sand, perlite, and coconut coir. The sand and the coconut coir gave me the most consistent results. There is also a good color contrast between the color of the roots and the medium so you can easily see when the seeds start to germinate. Over the years I have kept track of all the "stratification start" and "germination start" dates so now I know when to start my seeds in order to get them to germinate when I want them to. So I stratify most of my Prunus seeds at the beginning of January and they will begin to germinate 2 to 3+ months later, depending on the species. My plums/chums are on the 3 month end of that range. I generally get good rates of germination with this method. For the last 3 years I have also tried Fall seeding of the same varieties in seed beds. Germination rates, particularly with the plums, has been poor and erratic, with numerous seeds taking 2 years to germinate if they do at all. So I am now germinating almost all of my seeds in the fridge and then planting the seedlings out in beds as soon as the weather allows.

Plum pits are very HARD, it can take as long as 1 ½ year for them to crack open and sprout naturally. However if you crack the pit open and plant the small seed/kernel/almond-like thing on the inside they will be able to grow much faster. If you crack the pit, soak them in cold water in room temperature for 24+ hours and carefully peel off the skin you can see that they will already have tiny sprouts and then they only need to lie in moist soil for some weeks before a seedling emerges. This trick I've found works with any stone fruit, like the guy does in this video except I soak my seeds/kernels for 24+ hours: https://www.youtube.com/watch?v=686fccM2Gmc

If you try to sprout plums by keeping the whole pit inside the refrigerator it might never grow ever. Minimally you have to plant the whole pit outside and let cold and exposure help crack the pit open for the seedling to emerge out from. I think cracking the pit open is the least you could do to ensure a high germination rate though, but make sure to not use too heavy/dense of a soil and too much water because the seedlings damp off very easily I've found. You also have to protect them from birds and rodents outside who otherwise dig the seed up and eat it unless you cover it with some form of protection.

Here is a plum seedling from seeds which I just planted two weeks ago after soaking them for 24 hours and peeling their skin off: https://i.imgur.com/z5wlBnx.jpg

The seed came from a greengage plum(Reine Claude Verte) grown this year and the pit had been dry for 1 ½ months before planting or so. Here are three apricot seedlings two of whom which are from sweet apricot kernels that get sold in bags to be used as almonds lol: https://i.imgur.com/egSvHuC.jpg
So you can successfully plant even old and dried up seeds and stratification is not even necessary for stone fruit seeds, or at least with apricots/plums/peaches/nectarines.