There is one fact about starting seedlings early yourself – sometimes no matter what you do, they just take off and there you are, more than a month before you can even think about putting them into the ground (and at Chez Siberia, we’re talking probably 5 weeks from now unless I decide to throw caution to the winds), and the seedlings have outgrown their packs and hoo-wee, what are we going to do now?
Well, your Aunt Toby, over the past (ahem, well, let’s note get into how long, shall we?).. well, we’ve tried a whole lot of different methods here at Chez Siberia, to hold over tomato seedlings until ‘more auspicious times’. In the old days, when I could get waxed paper milk cartons, I’d sink them into those (and we also at that time had three Little Siberians, so we went through a lot of milk). These days, I’m just using pots, but if you have a source of waxed paper cartons (juice will also do; just make sure you rinse them out really well and punch a couple of drainage holes in the bottom. The secret is to match the size of the pot or carton to the length of the seedling above the level of the dirt.
You are going to — mwa-ha-ha — bury them.
So, take your carton and hold it up against the seedling and mark the top of that and cut the top off. if you have appropriate sized pots, then use those.
Using a really good potting mix (if it’s light brown or fluffy, this means that it’s got TOO MUCH PEAT IN IT. So, don’t use that. If you have that already, then add compost and something like vermiculite to hold water), put a small amount in the bottom – an inch will do. Pop the seedling out of the pack and GENTLY crumble the soil at the root level. You want to free up those roots. Then carefully take off the bottom set of leaves (trust me on this one) and put the seedling into the carton or pot.
Put in some potting mix around the bottom of the seedling and firm down well. Then holding up the seedling with your other hand, fill in the rest of the pot. Your tomato seedling should be just showing the regular leaves now and the plant will form roots all along the stem under the dirt. When it’s time to plant it out, just dig a deeper hole than usual.