Tiny seeds and gel-forming seeds should not soak before you plant them. Small seeds like lettuce, carrots, and celery take in water too fast through their thin coats. Seeds that form a slimy coating when wet, like basil and chia, turn into a mess you can't handle after soaking.
I made the mistake of soaking carrot seeds my first year of gardening. I figured if soaking helped beans, it would help everything else too. Those tiny orange seeds turned into a clumpy mess I couldn't pull apart. Half of them stuck to my fingers while the other half clumped at the bottom of the cup. The whole batch ended up in my trash.
Small seeds have paper-thin seed coats that let water rush in fast. They don't need help taking in moisture like hard-coated beans do. Drop them in water and they soak through in just minutes. Leave them too long and the baby plant inside drowns before you even get them into soil.
Mucilaginous seeds create a gel coating when they touch water. Basil is the classic case you'll run into. Get basil seeds wet and they puff up with a clear slimy layer around each one. That gel makes your seeds stick to everything except the soil where you want them. The same thing happens with chia, flax, and some flower seeds too.
These are seeds to plant dry, straight into moist seed-starting mix without any water bath first. Scatter them on top of damp soil or barely cover them with a light dust of mix. The moisture in your soil gives them all the water they need without drowning them or turning them into a goopy pile.
Here's an easy guide for you to follow. If a seed is tinier than a pinhead, you should avoid soaking seeds of that type. If you've ever seen the seed puff up or get slimy when wet, skip the soak for that variety too. Stick to dry planting and you won't run into any clumping problems.
Lettuce, carrots, celery, parsley, and most herb seeds all fall into the no-soak group. Flower seeds like petunias, snapdragons, and poppies also do best when you plant them dry. These seeds need careful surface sowing on damp soil, not a dip in water that makes them clump and stick together.
Save your soaking bucket for the big tough seeds like beans, peas, corn, and morning glories instead. Those thick-shelled seeds can handle a night in water without any harm at all. But keep your tiny seeds away from soaking bowls. They'll thank you by sprouting evenly across your seed trays instead of stuck together in clumps.
Read the full article: Starting Seeds Indoors: A Complete Guide
