The next step how to grow roses from seed is to sprout the rose seeds. After having gone through their “stratification” time, take the containers out of the refrigerator and into a warm environment of around 70 F. (21 C.). I do my best to time this for early spring when the seedlings would normally be coming out of their cold cycle (stratification) outside and starting to sprout.
Rose seeds need to go through stratification (an artificial cold spell) for 10 to 12 weeks before they will sprout. This, combined with a germination success rate of 20-30% makes propagation by seed an unattractive prospect. on by seed an unattractive prospect. If you still want to try it, find a good source of information that will guide you through the process.
A special stainless steel screen on the handle of the unit raises up when it is dry. When this happens, it throws the mercury switch which opens the solenoid valve and starts the misting cycle. When this stainless steel screen accumulates enough mist, the weight of the water drops it down again, shutting off the mercury switch, closing the solenoid valve. It needs practically no care or maintenance and can be left on, unattended day and night. This control unit is a very practical instrument which will have a long lifetime of carefree maintenance. There are no clocks to adjust, and it is not affected by water conditions. It works simply on the weight of water. The major benefit of the Mist-a-Matic is to control the misting cycle according to weather conditions. Too much water promotes disease and wastes water. Too little water causes leaves to wilt and failure to root. The Mist-a-Matic distributes the correct amount of water. In hot weather, the unit will turn on more frequently as the water evaporates. In cooler weather, the unit turns on less frequently. For operation, you will need to plug the unit into an electrical outlet. You need to hook it up to a water source with misting nozzles.
To get the best success, yor rose seed will need a period of stratification (a cold period of about 6-12 weeks). Its a good idea to time this so that it coincides with when they would naturally start to grow in spring – probably around early March, depending on weather conditions. I would look to sowing them in late November/ December and popping them outdoors or if we have a mild winter then stick them in the fridge!
Prepare a large hole. You'll need one for each rose bush you're planting. Use a garden spade or shovel to dig a hole 18 inches (45.7 cm) wide and 18 inches (45.7 cm) deep. The measurements don't have to be exact, but a hole this wide and deep will be suitable for most roses. Mix the soil you removed from the hole with compost, and use some of it to form a small mound in the base of the hole. Add some bonemeal or rose fertilizer.