Allowing harvested seeds to completely dry out?

I usually have lots of seeds that have germinated by now but this yr., not one of my early harvested seeds from last summer has germinated. I do have about 50 seedlings from last yrs. seeds and two lots of late harvested (way after Christmas)seeds have had some germinating. Last yr was hot, dry and there was mandatory water rationing which pretty much everyone saw coming. So I did have some successful very early crosses and a few later but still early to mid-season hips. All the early crosses were harvested, shelled, and left to dry in their labeled baggies as were the later crosses. Usually I try to get some vermiculite with the added ammonium nitrate into the baggies and stash them into the Fridge before Thanksgiving but lots of stuff got into the way this yr and they did not get this treatment until around New Yrs. The late harvested hips/seeds seem to be doing just fine so I am assuming that it is the early and prolonged drying time out of the hip(s) that has created the non-germination problem. Any experiences with this (unfortunately this is most of my new seeds) and can I expect a few germinations, just a bit late, or even next yr?

I am assuming that it is the early and prolonged drying time out of the hip(s) that has created the non-germination problem.

It’s no clear to me that you actually dried the seeds completely but, if so, then they would have gone dormant on drying and revived on soaking in cold oxygenated water for a day or two. From that point on their vitality would depend on how mature they were when they were harvested, the viability of the particular crosses and similar normal factors. Bottom line on drying is that it is not lethal, and is actually a good storage state, provided it happens fairly soon after harvest of mature seeds.

I think they were pretty completely dried out. Most of the crosses had been made in March-April to mid May. They were harvested mostly in July and August. The hips were colored and many of the sepals had fallen off. A few of these were early ripeners (past experience) and a couple could have been picked early out of convenience, but when I pruned in January there were a few hips hanging on that had been left because they had not ripened. I have made the assumption that it was the shelling/drying that has ?delayed? their germination because the few that were not shelled/dried but were left on the bush are germinating fine (one batch-{GeminixBlack Magic} X {Gemini x R.Altai} has germinated 18 out of 30 seeds). I am also having a really good year for dropped seeds/hips that are germinating in cans under the mother plants, which may be attributable to our early and generous Nov.& Dec. rainfall. I did not soak the seeds before applying the ammonium nitrate/water solution, but they did absorb a bit more than usual which now looks like it might have been the mistake. That was a little bit like soaking the seeds in the ammonium nitrate solution to rehydrate.

Hi Jackie!

I did a study on the effect of a few days of air drying seeds versus keeping them continually moist. It was shorter it sounds than the duration that you stored your seed dry. Depending on the genetic background it either did not matter or short term drying reduced germination after remoistening and a stratification period. Since this study I try not to dry out my seed if I don’t need to in order to get high germination rates. I tend to try to delay germination by a couple months of warm stratifcation before cold. I tend to get more uniform germination when they do germinate by combining warm and then cold stratification.

Part of the reason I wanted to look at the effect is that in the plant propagation labs I was a TA for in college we worked with apple seed and found drying of apple seed reduced germination and I wanted to see what the effect would be on roses.

Here is the link to the HortScience paper

Hips I ripen are picked when they are red all-around and not soft. They are cleaned a placed strait into vermiculite and nitrates in the fridge. I have never been able to germinate hips that are wrinkled or fully dry. Seeds are from rugosa/woodsii/blanda.

This year I tried an experiment with drying seeds before stratification to see how well they would germinate. I did this to delay germination of the seeds by a few months so I wouldn’t have to grow them under lights so long before planting them out. I harvested the hips from one plant in late September, shelled them and placed the seeds in a baggie. I only dried hem for a few hours before I placed them in the baggie. I placed one third of the seeds into warm stratification in mid November, the second third in late November and the last third in mid December. I wish I had used seeds from more than one plant in this experiment because these seeds started germinating within three to four weeks of warm stratification. The seeds placed in warm stratification first had the lowest germination rate but still pretty high at 45%. The other two are 56% and 55%. So with these seed anyway, drying them for 6 to10 weeks didn’t seem to hurt germination.

Paul, what type of Rose did you use?

Hi Johannes,
It is a second year seedling of ((Prairie Princess x Louis Jolliet) OP) x (Hot Wonder x 1T20).

I did leave these seeds to dry in open, labeled baggies for approx 5 months in very warm dry weather. This and rehydrating them with the very dilute ammonium nitrate water (not cold clear water) were the two things that I did differently than past years. Usually I have left them in their hips until October and then shelled, washed them and put them in the fridge in their closed labeled baggies so they did not dry out excessively. Then in early Nov I would add vermiculite moistened with ammonium nitrate dilute water and place them back in the fridge for 30-45 days. If they do not start to germinate I will hang on to them until next year because there are more than a few that I really want to see germinate and grow.

As near as I can tell, the effect is very species dependent. The most surprising was a study in Romania? or Bulgaria? where keeping seeds, used for rootstock, up to 8 years improved their germination %. Also for some species the recommended practice is storage for a year (R. soulieana grown and studied in China.). I have been playing with R canina and have some that I kept for at least a year dry and cold. They give good germ % but take longer than with direct treatment of hips harvested at optimum ripeness. Rugosa left out in the cold, as hips, in Lincoln NE, germinated well, and even after sitting on a lab bench for many months they gave reasonable germ %.

I suspect that introgression of tropical species affects the pattern of dormancy. Maybe also generations of selection for rapid germination in European breeding programs from say 1800 onward (10-20 gen) has removed the dormancy factor, and with it the ability to survive being dried.

I do not know why I did not make this association before but it is the probable cause of the seeds not germinating–and it also probably means they never will germinate. In Mid November we had the house fumigated for termites. Of course all the seeds were placed in (doubled) nylafume bags, which is what the fumigation co. gives you for all toiletries, stuff in the fridge, all foodstuffs, etc. It is supposed to keep out the fumigant and keep the contents safe. While we did not have a lot of stuff to put in these bags, we did have some, esp. from the bathrooms (soap, shampoo, etc.) So I double bagged the seeds, which where exceedingly dry, and they where among the few things that stayed in the house. My husband, who has a chemistry background, got very paranoid and moved all the bagged foodstuff out of the house and into a van parked in the driveway. The warning literature repeatedly says that the drier the contents, the more likely the fumigant will penetrate, but they also say that the nylafume bags keeps even food safe and edible. All plants surrounding the foundation where damaged (or not) in almost exact proportion to how wet or dry they were. The few seeds that I have germinating now were either from last yrs.- -not in the house, but stored in an area outside the fumigation, or they were from a few hips that I missed picking but saw when I started pruning, which was in Dec. and Jan. Not one seed seemingly has survived the “safety” of the nylafume bags.

What kind of fumigant was that anyway? I would expect most plants and their seeds to detoxify most anything reactive enough to kill termites, at least up to reasonable levels. Maybe the problem is that the bags are too impermeable for oxygen to get to the seeds and they can’t mature that way. Around here we use bait for termites containing juvenile hormone. It is very specific for that genus of insect. Harmless to other organisms. They carry it back to their nests and wipe out the whole colony.

I would not give up on the seeds. If you stratify in something like moist peatmoss, any reactive chemicals ought to diffuse out and react with the peat. It may take warm + cold cycle to get germ.

First off–yes I am going to try to germinate the seeds, possibly soak them and then plant out in appropriate planters. I did have quite a few green plants that where ‘adjacent’ to the canvas covering the house that died. Some plants detoxify better than others. A Ficus benjamina (tough plant anyway) was under the tent and while it did loose many of its’ leaves afterward, it is now looking good. My little orchid greenhouse only has a couple of tillandsias still living. This was not even under the tent. The seeds were only in the Nylafume bags for about 10-12 days. The fumigant is Vikane, commonly used here in Ca. and it is supposed to penetrate wood. Termites are a bit more of a problem here and we have a few different varieties, plus carpenter ants and wood beetles of several varieties. I live in an all wood house–not the best idea here, but very popular in the 60’s-70’s, and it is built into a hillside.

Since it did not really occur to me that this might be the problem (if it is something else, I cannot imagine what it could be-I did not do many things differently from previous years) until just recently (fumigation was in November-I left town for 10 days because I have had bad health reactions just walking past tented houses) and it is getting close to the end of germination season here unless the seeds are seeded in the soil.