Roses and the Sigmoid Curve

Total germinations counted on a daily basis, and total culls seem to follow a sigmoid curve in my greenhouse.  Knowing this helps me to anticipate the changing workload of this hobby.  Rose seed germinations in general seem to start out slowly in the first month after planting the seeds in late December to early January, but then really pick up speed in the second month (usually February).  Then in the third month germinations slow down again.  Usually, I can expect 75-80% of germinations in the second month after planting the seeds.

Likewise, my rate of culling follows that same patten but is delayed by 8-10 weeks (which is the time that it takes for newly germinating rose seeds to bloom for the first time).  Though I was very meticulous in record keeping during my first two years after building our greenhouse (counting germinating seedlings almost daily, and counting daily culls), I only count germinations 3 or 4 times per year now, mainly focusing on calculating the germination rates of potential new seed parents.  Below are two charts from my first 2 years of hybridizing in our greenhouse.

This year, as is my usual habit, a portion of my seeds that were planted have come from some of the newer seedlings that have shown a tendency to set hips well.  These seeds came from open pollinated hips (meaning that I didn't spend any time doing cross pollinations on them).  Usually, I will only plant 10 hips worth of seeds to get an idea of about how many hips it takes to get a certain number of seedlings, but for some of the better seedlings, I will plant all of their seeds in hopes that something good will come from them.  Since the germination rates are unknown, I plant the seeds rather densely.  All of the seeds planted on the left side of the seedling bed shown below came from potential new untested seed parents, coming from open pollinated hips.  You can see that some areas seem to have no germinations (like the uppermost area on the left), while other areas are showing excellent germination.

A closer view of the more densely germinating area above is shown in the photo immediately below that was taken last week, while the second photo below is of the same area that was taken yesterday.  The warmer weather this past week has caused the seedlings to sprout like crazy.  During the first month after planting, there was a total of 2,059 germinations.  Over the last week there have been more than double that number of new germinations.

This area was planted with open pollinated seeds from a seedling code-named Q199-1.   I am very pleased that this particular seedling has an excellent germination rate.  It was the result of a cross between 2 of my favorite Hulthemia seed parents, and seems to have a better plant and blotch than either of its parents.

I'm looking forward to the first blooms, but it looks like I had better expect to be busy in about 8-10 weeks…..