Benzelsanswered grow question 3 years ago Depends how small, but as long as its around two weeks old or more it will be fine. Just be real careful to not let the damaged part of stem get wet, at all for a few days. If it gets wet or even worse, wet and dirty, it will rot. Ive used alfoil (tin foil, aluminium foil) to make a lil splint to wrap like a cast for a broken arm or leg to hold the stem straight for a few days on really small young seedlings before with some luck, but if the soil was a bit too wet when I snapped the stem, the repair jobs never worked out too well as the stem rotted. Or ive used bone dry perlite to mound up around the stem to hold it straight while plant healed. thats not a bad idea but dont use soil unless its dry.