I try to prepare myself. I try to use methods of planting that will yield conservative numbers of unnecessary seedlings. I try. But when the seeds are so little (petunia seeds) that they are hard to see even with reading glasses, picking up and planting just a couple per cell pot is challenging.
The little seedlings all looked so healthy, full of potential! I had planted them in cells in trays because I was going to try to avoid unnecessary transplanting time. I am still happy with that decision, as I won’t have to transplant them all, like I will for the flowers that are in an open tray. (see far left in top photo, which are salpiglossis and phlox seedlings)
I just couldn’t simply thin them in the traditional sense. I had to try to save some of them. Of course, some of the petunia seedlings were so close that pinching away some plants so that one plant had a decent chance of growth was the only good option. The less any roots are disturbed, the less of a set back for the plant.
Examination of the trays led me think that some of the more spaced seedlings could be lifted out and transplanted to new homes. If I did the thinning first, I could get a better idea of this.
Here is half of the petunia flat as it looked before I began thinning:
The petunia seedlings were so delicate that they tended to come out by the roots as I was pinching them. As I got closer to the plant I was saving, I had to be more careful of this, so it didn’t accidentally come up with the others. I found it useful to wear my reading glasses and make sure I had good lighting.
The leaves on top are obvious enough, but the baby stems are like translucent lime-green pieces of hair. Bare fingers worked best for teasing the plants apart and delicately grasping the stems. There is no tool as precisely sensitive as a bare fingertip.
After thinning, the 4 cell section looked like this:
As usual, a popsicle stick is just the thing for lifting the seedling out of the soil. This works best if the soil is not too moist OR too dry, so I try to water my trays a few hours before transplanting. Holding a seedling by a strong leaf is generally the most reliable way to transfer it safely to it’s new pot, but sometimes there is enough soil clinging to the roots that the root ball needs to be held so it doesn’t break the stem. Once in a while, the root ball was substantial enough that it made the most sense to just hold it in my hand or on the stick.
When it was over, I had a whole new tray of petunias, worth about at least $10, more like $25 if you want high quality plants. Not bad for an hour’s fun work! I still had a sizable pile of casualties, but I didn’t feel as bad about that since I had also doubled my petunia production.
I did fill in the holes that resulted from removing the plants. Then, I used the mist setting on my nozzle to gently water both trays, helping the soil settle around the new transplants in particular. I will keep an extra close eye on them for the next couple of days. The new transplants will need to remain moist until the roots get better established. I want to monitor the other plants, in the pots that were just thinned, just to see how they are doing.
Three days later,it is easy to tell which tray is growing best. They were all about the same size to begin with. There were enough seedlings that I chose the most vigorous plants for both saving and moving. The transplanted seedlings look good, but are still about the same size. Those that were barely disturbed are loving the extra space.
Thinning and transplanting are most successful when the plants are small, and have recently developed strong true leaves. Then they have enough top growth to help them through the transplant process, but not so much that the stressed roots will have a hard time sustaining while they get re-established in the soil. However, never let the lack of supposed optimum conditions keep you from trying things. If you keep experimenting, you will learn useful things and develop a good sense of how to made gardening work in real life, where timetables are unpredictable. Just enjoy the whole effort, whether it is “perfect” or not!