This article on rose seed germination is written by Henry Kuska. Thanks to Henry for sharing this with all of us. You can see his page at http://home.neo.lrun.com/kuska/ There is lots of great technical information there!
Rose Seed Starting Method (1996-97 Season).
I remove the seeds from the hips when the hips have color or if it is getting near freezing outside (usually middle or late November). I soak the seeds for two days in a enzyme drain cleaner solution that states on the label that it will dissolve paper. I then rinse the seeds and put each set of seeds in an individual clear plastic round container (16 ounce size) with a clear plastic lid that simply sits on the container - not air tight. Eight containers fit into a standard seed tray. Each container has polyester batting in the bottom and a layer of synthetic cloth on the batting. Water is added in excess to the container. After a short soak the excess water is poured off. The seeds are then placed on the synthetic cloth. The tray is then placed into another tray that has a commercial 6 foot heating cable with an above 70 degree turn OFF thermostat taped to the inside bottom with duct tape. The cable is covered with dry perlite. (Actually for both trays I use two trays each for additional strength.) I have a piece of sheet aluminum placed between the two layers of the doubled seed tray to help evenly distribute the heat. The heating tray is placed on a Styrofoam board on a shelf in my unheated sunroom. The power cords from the 70 degree -turn OFF- heating cables are connected to a 120 volt double pole thermostat that I have set to turn ON when the sunroom temperature drops below 50 degrees F.
The covers of the individual containers are of the indented kind so that water that condenses on the inside bottom of the cover will fall back on the seeds. The bottom of the container is being heated to near 70 degree F while the cover temperature is close to the temperature of the sunroom - often between 40 and 50 degree F. (I use this method to simulate "rain". A common observation from those that plant their seeds outdoors is that the seeds will sprout after a rain. It is expected that this is because the rain washes the inhibitor chemicals away from the seeds).
The seed trays are covered with red transparent wrapping paper (there is a literature paper that reports that red light can increase the germination from about 20% to about 80%). The seed germinating set ups are placed on shelves along two mainly glass walls of the sunroom. One wall (west) gets direct sunlight, the other wall (north) does not. Each day I remove the individual 16 ounce container farthest to one end (called the "last" position) of my last tray - this year tray 29 - and move up all of the other containers one position. The removed container goes to a small refrigerator that I keep in the sunroom. The refrigerator is kept at about 40 degrees F. There are always 8 containers in the refrigerator. Each day one seed container goes in and another (the longest in ) comes out. The one coming out goes to the opposite end of the heated trays (what I call the "first" position) in tray number 1. Also any container that has a sprouted seed is removed from its position and placed at the "first" position in tray number 1. My keeping the seeds in a refrigerator for approximately 7 days is based on a published embryo culture research paper that reported that seven days of cooling benefited germination. For the 1997-98 season I am planning on using 20 days of cooling as some batches did not germinate with only 7 days of cooling.
Each day I examine the seed containers. The sprouted seeds are removed from their containers with tweezers and placed in a solution containing Sorbitol, Captan, and Cleary S3336 WP for a few minutes. (The Sorbitol is added because a research paper found that Sorbitol helped in embryo culture of roses. The Captan and Cleary were chosen after testing a number of fungicides with bean sprout seeds.) The sprouted seed is then placed on the surface of a 1 3/4 inch square peat pot that is filled with a previously wetted commercial seed starting mix that does not contain fertilizer (I use the type that includes a wetting agent). I make a small indentation in the surface and position the root end of the seed downward. The seed is then covered with dry perlite - no additional watering is done through the perlite. This size square peat pot allows 50 to be placed in a standard seed tray. The peat pots are put on a layer of wet perlite so that if the roots come through the bottom they will not be in air. Also, except for the initial watering of the mix and pots all watering is done from the bottom by pouring water into the perlite through an empty space in the 50 pots (I remove one of the pots so I only have 49 per tray).
Commercial clear plastic domes are put on the seedling trays, and two "double 40 inch florescent" shop lights with cool white bulbs are placed directly on the seedling tray covers. The trays are placed perpendicular to the direction of the horizontal shop lights so that two shop light fixtures ( 4 lights) cover 4 seedling trays. The lights are kept on 24 hours a day. The individual seedling trays are put into thermostat controlled heating trays that are set up in the same way as the seed sprouting trays described earlier.
When the leaves of a seedling are almost touching the top of the plastic dome, that particular peat pot cube is removed and transplanted into a 3 inch square peat pot that is half filled with a commercial potting soil that contains a low dosage slow release fertilizer. Additional potting soil is then place around the inner pot. The 3 inch square peat pots are placed into a clear plastic Rubbermaid "Big Storage Box" that has a commercial 12 foot 70 degree - turn off thermostat taped to the bottom and covered with wet perlite. The dimensions of the box are 39 inches by 16.4 inches by 9.2 inches height. Each box holds 44 of the three inch pots. After a box is filled with peat pots, Perlite is added to the top and to the empty spaces between the pots and the plastic walls of the box. Two sets of double light 4 foot florescent shop lights (also with cool white bulbs) are placed on each box. The lights are kept on for 24 hours a day. When the plant leaves reach the lights, the lights are removed and the box is placed on a shelf next to the windows. From then on the plants must do with window light until transplanted outside in the spring. The plants are bottom watered by running water down the plastic sides of the containers into the perlite layer. With a few of the waterings I add a commercial fertilizer with trace elements at the recommended concentration. It is easy to see the level of the water through the clear box sides.
Other comments: The sunroom is wired with two independent 15 ampere circuits. Each circuit is protected by its own ground fault interrupter and circuit breaker. The cool white florescent lights are on one circuit and remain on 24 hours a day. The heaters are on the second circuit and are controlled by the room turn ON below 50 degree double pole thermostat and by the individual turn OFF 70 degree thermostats. In three winters of use I have not had any plant freezing. A few times when the temperature was predicted to go down around -25 degrees below zero, I put Styrofoam panels in the windows and placed loose plastic drop cloths on the open mature plant boxes.