PRO and CON: Expanding Pot-Pellets for Seed Starting

I sometimes start seeds in expanding starter pots. The most widely available brand is Park Seed Company "Jiffy-7" pots. The Jiffy pots are widely available in garden centers, the garden section of large retailers and hardware stores. They don't work for all seeds, but it's a product that is worth considering for starting some of your seeds.

The poker-chip size disks inflate into seed starting pots when you soak the discs in warm water. After the disk has soaked up water and is about 1 1/2 inches tall, drop a couple of seeds into the hole in the pot and wait for something to grow. I haven't had this much fun since I was a kid and had those flat animal sponges that puffed up into horsies.

Expanding Pots: as purchased on the left, after soaking on the right

I used some clear plastic salad greens boxes and shoe boxes as greenhouses instead of the commercial one, because I'm a cheapskate. The boxes worked well, first covered to retain moisture and then uncovered when the seedlings were put outside to get used to the weather.

Serrano Peppers, getting used to the outdoors.

Summer Squash, roots escaping through the mesh

 Advantages of Compressed Peat Pots:

• Stored compressed, the disks take up less room than a similar volume of potting soil.
• They can provide even moisture delivery during germination.
• It is less time consuming than using seed starting flats and having to move the plants from flats to small pots and then to the garden.
• There is less risk of loss to birds and bugs compared to starting seeds in the ground. The quail around here taste everything.
• The peat pots can either be planted directly into the garden or "potted up" into a larger pot for more maturing or to wait for warmer weather. 

 Disadvantages of Compressed Peat Pots:

•  Peat might not be a renewable resource. Some persons claim it regrows fast enough to be considered a replaceable resource, others say it's as irreplaceable as old growth forests.  I haven't researched the ecology of it. A version of these pots that uses coconut fiber (coir) might be better.
• It's easy to forget which plant is in which pot. If I use this method again, I will use smaller containers and have one variety per container. I have a half-dozen mystery squash, which might be luffa, butternut or pattypan squash, because the dog tipped over that container.
• The peat cylinder, if you don't bury it completely, can harden and become impervious to water or even pull water out of the soil.
• In this dry climate, the water evaporating from the peat chilled the roots to below the air temperature when I left the pots out all night. That may explain the slow germination of the heat-loving plants like eggplant.
• The mesh coating has to be ripped off because it isn't biodegradable, and ripping it off might damage the roots. 
• There isn't enough room in the cylinder to keep anything with a vigorous root system long enough. Okra and squash, for example, had roots coming out the bottom of the mesh long before they had true leaves. 

Conclusions about Compressed Peat Pots:

The seeds that made the best use of the compressed peat pots were small to medium seeds such as tomatoes, tomatillos, eggplant, and chilis, which only needed to get a couple of inches tall before being transplanted to the garden.

I won't use these pots again for tiny dust-like seeds, such as oregano seeds because it's impossible to put in just a few seeds. The seedlings crowd each other badly.

I won't use these pots again for large seeds, such as squash and large beans. There isn't enough room for the seed to sprout, and some of them split the peat in half before they had true leaves.