I don't know what happened to your leeks, but I do start a lot of seeds in peat pellets and then pot up to 4" plastic pots before transplanting outside. I haven't had any problem with plants dying doing this. Sometimes I get busy and don't pot them up very quickly, but the seedlings will continue to grow with their roots coming out the sides of the pellets if they are in trays. They do grow into other pellets, but I hate to say this, I just rip them apart (ow!) and plant them and they are always fine. IME, there is no such thing as transplant shock. I grow all sorts of plants - herbs, flowers, perennial, veggies - but I have never grown leeks. Maybe there is something about them that didn't like the peat.

I used to use the peat pots but they were hard to get, so I switched to plastic and like it better because I can reuse them year after year. I bought a whole bunch from either Fedco or Peaceful Valley couple years ago.

The peat pots seemed to dry out very, very quickly. The moisture retention factor is better in plastic pots, yes? I'll switch to plastic and see if I get better results.

Yep, watering is much easier with the plastic pots. The way I remember it, with the peat pots the bottom would start to disintegrate with regular watering while the top would be crispy and often never disintegrate at all, even when it was planted.

What about those types of plants that don't like to be transplanted? I think morning glory is in this category is it not? Should I take my chances with the peat pots?...or are they likely to survive a move from plastic pots?
Please advise.
Thanks.

In my experience, As long as you're careful not to destroy the roots when removing the plants from the pots they will be fine. I've never lost a plant that "resents tranplanting" and I do it all the time. Actually, with Morning Glory, I dig them right out of my garden to move them around and they do very well.

I cut drainage holes in cheap disposable plastic cups and use them for 'pots'. They are generally big enough to accomodate the root systems in plants that outgrow peat pellets (I had that problem last year!!). This year I started cutting drainage holes into the bottoms of the little plastic dixie cups, filling them with miracle grow potting soil, and using those in place of peat pellets. It's much cheaper and they stay moist longer than peat pellets. Do NOT, however, use paper dixie cups---I have trouble with them growing mold all over the outside of the cups!

I have used plastic cups too. Only thing bad about them is they tend to be top-heavy and tip over. You can make holes in the bottoms with the tip of a phillips screwdriver.

I started seeds in peat pots with peat pellets. Some of the plants (particularly the pumpkins) have roots growing through the peat pots. Should I keep them in the peat pots, or not. I can't move it outside untile about 4-5 weeks. Not sure how long I can keep it. I am also growing peppers and lupins in peat pots with peat pellets. Any suggestions how I can maximize the situation so they last until I can plant outside.

I saw no problem with the transplanting process. You simple transplanted the plant, pellet and all into a larger pot didn't you? Did you water it right after the transplant?

Although you hadn't described how they wilted it brings to mind the fungus DAMP which causes a seedling to suddenly wilt (bottom to top). A perceivable browning occurs in the lower part of the stem and the seedling wilts overnight. This is just another possibility you should consider.

Sir Brandon, you should begin to transfer your seedlings to larger containers. The seedlings will continue growing until the weather permits outdoor planting.

I'm using the pellets too, my very first time to do so!
My question is, I've started an assortment of seeds, my problem is with the sunflowers that have popped up, their so top heavy they've fallen over, when I go to a peat/plastic pot, do I pay special attention to the base of the sunflower so it doesnt rot because new dirt is too high?

mamafish, I suggest using peatpots because you can simply plant the entire thing in your garden without disturbing the roots. Re your question, first put a layer of soilless mix to the bottom of the pot and then put your peat pellet on top leaving the base of the plant at near the rim of the pot.

Ianna