What difference does size make??

I am really revving up for the spring planting season already. My greenhouse (hoop house) is almost completed, and I am learning all I can about propagation. My goal is to grow lots and lots from seed. I am looking into purchasing seed trays and seed starting supplies.

I think that the Jiffy pot peat ones sound like a good idea since there is little transplant shook and less work involved. My question is: What difference does it make in the size of the pots I choose to buy? Why does this matter? Would it be because some plants would be larger than others and not planted until they were bigger? The choices I’m seeing range from the pellet size to the 4.5 inch size and what determines which ones I use please?

I am not going to be able to broadcast seed directly onto my beds at all just yet since I have heavily amended with aged horse manure and I‘ve put down a pre-emergent to help keep the weeds at bay. It’s my understanding that they take a few years to filter out and then I’ll be able to directly spread seeds.

Thanks!

Susan


This message was edited Dec 30, 2007 2:51 AM

The jiffy peat pots (I mean the actual pots and not the pellets here) are fine for plants with very strong root systems. Plants that don't have strong root systems can't break through the pot in the first year simply become root bound in the soil and die off before the pot can degrade in the ground. As an illustrative point, I sowed several lots of seed in jiffy pots, which I aquired very cheaply, and managed not only to grow the seedlings but to knock them out of the pot and save the pots for this autumns sowing. The seeds I sowed would never have managed being plated out in those pots. Like the pellets, these are better suited for strong growing seedlings and shrub cuttings than general seed sowing.

As for pot size you don't want to use anything much bigger than a 5" pot, partly to save on space and partly because some seedlings like their roots to feel the side of the pot before putting on much top growth.

I use washed out yoghurt pots with holes in the bottom for much of my seed sowing and transplant to larger pots or in the ground early, this helps to lessen the transplanting shock surprisingly enough because they are moved when they are very young.

I'm really new at this, but I can say I sowed several trays of peat pellets (the Jiffy-7 ones) and several trays of peat pots (2.5", I think) this spring. I had great success with the pellets, good germination, easy to transplant and handle. The peat pots were less successful - I don't think I had any survivors eventually. Not sure why after all this time (lol), but I think part of it was that they kept on getting knocked over (kids, dogs), and the peat pellets don't mind, but all the soil fell out of the peat pots and the seedlings didn't like that. If I remember the tomatos wouldn't grow to more than 6 inches, even after transplanting - they must have been struggling to get their roots out (thanks, Baa). Once I had bought decent seed starting soil the pellets came out cheaper, too. One thing I have changed for this year is that I have drilled a few small drainage holes in the bottom of the tray which holds the pellets/ pots. In spring several of my trays "drowned" when they got moved outside and it rained unexpectedly.
Larger peat pots might be nice to transplant the peat pellets into when the roots start sticking out of the sides of the pellet (some cosmos I sowed this fall were too big for the pellets within about 3 weeks).
Natasha

Great info, Thanks! Okay, since I am unsure of exactly how strong the roots are on the things I intend to grow from seed, maybe I should use the more traditional reusable pots and transplant them when ready. Which leads me to ask again, so does it really matter what size of potI use? Do nurseries use the smaller six pack for space consideration or do all/some/most? plants like to have their roots touch the sides at first?

Thanks!!

Susan

The six packs of cells are for space and money saving (less compost). It's a waste of compost to use big pots for seedlings unless you intend to grow them in that pot for a very long time as the plant just doesn't utilise the space. You can sow in trays and then transplant into pots but that is extra work and extra compost :)

On the roots touching the side - I find it's cuttings like Fuchsia, Acer seedlings that really prefer this, however it's not uncommon for plants to seek out the limits with their roots before growing upwards.

This message was edited Nov 8, 2004 7:17 AM

Great info, thanks, since I just bought some jiffi pots, I'll know what not to grow in them!

I never use peat pots here. Our summers are cool and short, so they don't break down. The plants are bound up in the pot, and if you try to extricate them, they are embedded in the peat pot. I just can't use them at all. In hotter climates, they may do fine, but not here.

As for what size pot to plant in, I would decide whether you want to thin or prick and transplant. If you are simply thinning, a larger pot is fine.. just thin the additional plants and let it grow. Otherwise you're going to be transplanting them anyway, so what's the difference.