Bumping seedlings up to bigger pots for our plant sale!

We are growing about 10,000 plants for our plant sale this spring. We don't have a big property or even permanent greenhouses, so we need to make the most of our space. We start seeds in small seedling trays and then bump them up to bigger pots when we are ready to put them in the greenhouse. The expansion from 72-cell pack to pint and quart size pots is amazing. We only have a few shelves inside but they will more than fill all of our greenhouses over the next week. We have learned a few things about transplanting with all this practice! Here are a few tips.
1. Make sure the plant plug your are transplanting and the soil in the pot you are transplanting into are both moist for best results and minimal transplant shock.
2. Treat your transplant like you would a goldfish being moved to a new tank and don't make sudden changes in temperature or light. If you are sending your transplants outside for the first time, do it on a cloudy day or towards the evening to avoid stress and avoid big temperature swings.
3. Some seedlings can be planted deeply to create a stronger root system and to help correct leggy seedlings. Tomatoes and tomatillos are good examples. Some seedlings will rot if the crown is planted deeply. Strawberries are a good example.
4. Be careful not to damage the roots or stems by easing the seedings out of the tray instead of pulling them up by the stem.
5. Not everything likes to be transplanted. Most plants with a taproot should be directly seeded into the garden. Carrots, beets, parsnips, rutabaga, radishes are good examples. Some plants are okay to plant early to transplant into the garden, but should be transplanted young and more carefully. Peas, cucumbers, squash, melons and beans are good examples. You can give them a head start by planting them a little early but they will not do well if they have grown too large or have been transplanted multiple times. Some plants really need the extra growing time and are best transplanted instead of directly sown. Tomatoes, peppers, eggplants, most of the brassicas are good examples.

[@sljallen]

Thank you for the helpful information

[@linhlittleford3652]

So helpful! Thank you.

[@priayief]

Years ago I saw a video where a gardener transplanted tomato seedling directly from a small seedling tray into the garden. My practice had been to routinely pot up my small seedlings well before transplanting.
I was intrigued by the idea of not having to spend the time and effort of potting up but I wasn't sure how well these younger and smaller seedlings would do. So I did an experiment.
For half my tomato seedlings I did what I usually do. For the other half, I started my experimental seedlings about 3 weeks later. I hardened them off then I transplanted the entire crop in the garden.
The younger, tender seedlings looked so small and frail compared to my traditional that I was skeptical that this novel approach would work.
To my surprise, the younger seedlings caught up to the "traditionals" and produced at least equally well.
I ended up saving a whole lot of work.

[@iowabackyardfarmer2952]

This is a good point. Tomatoes can grow really fast. If you have seedling that sits in a tray or grows too big for the pot they are in, that growth rate slows. A younger plant still in fast growth mode can pass it. That is part of why planting up to a bigger container can be helpful. If you’re careful you can get a big advantage in time to tomato harvest with bigger plants, but you have to keep them in a growth mode. If you weren’t worried about having a super early harvest the smaller seedlings take up less space and are more economical. You just have to resist planting them too early! Thanks for sharing your experience!

[@priayief]

@@iowabackyardfarmer2952 Agreed. Like most new gardeners, the first few years I grew my own seedlings, I started way too early, and I always potted up. Even when I learned to plant later, I still potted up, assuming this was necessary. I guess, in a way, it was necessary because I always germinated in sterile germination mediums then used potting soil when the seedlings matured. That way I figured that the potting soil would provide the needed nutrients.
It occurred to me that I could avoid potting up in two ways: first, I could provide fertilizer to my seedlings or, second, I could start my seedlings in potting soil.
I liked the latter option but I wasn't sure that germinating seeds in potting would work that well. So I did my own germination trials comparing potting soil to several other germination methods. To my complete surprise, I found that I could germinate not only tomatoes, but other vegetables in potting soil with not much difference.