Garden Fail: Peat Pots

This is my first year using peat pots to start seeds. In the past I have used either peat plugs or soil blocks. They all have their pros and cons, but so far I am still adjusting to peat pots (if I do adjust). In case not everyone is familiar with the different terms, I will include pictures of them all.

Peat Pots

Soil Blocks. I actually have a nice tool I purchased to make soil blocks, this picture was taken by someone else (see credit at the end of this blog post). I didn’t have a soil block made at this time.

Peat plugs

The first time I grew seedlings I used peat plugs. They are great and very easy to use. The soil stays in the biodegradable netting, the moisture seemed pretty uniform, they have the right nutrients for the plants. The con is, they are pricey. To save a little money after a couple of years of peat plugs, I invested in a soil block maker and tried using it for seedlings. It was a little hard to get used to making the soil blocks. The moisture had to be just right or the soil would fall apart or be overly saturated. After planting the seed, and after it grew a little, it seemed like the outside dried quickly and on occasion they would fall apart (which is so sad to see: all that work of raising a seedling going to waste). Next time I try them I will try using some different soils that may help them stay together. It does require the soil to be more compact and I wonder if that stunts the growth of the seedling; maybe this would be a good experiment for next year. I really like how transplanting is so easy, I just stick them in the ground and that is it. No waste and the roots can easily grow onto the new soil.

This year was my first experience with peat pots. I don’t think I would have ever purchased peat pots because even though they are biodegradable, it seems a little wasteful to be purchasing and using more every time I plant a seed. I do like the idea of not using plastic which means possibly less toxins leaching into the soil and eventually the plastic will likely go into the landfill. The peat pots provide less transplant root disturbance if placed directly into the ground when they are ready to transplant.

I always wonder if it is a little hard for the roots to get through the peat pots. I transplanted my tomatoes into larger plastic pots and I pulled away the peat pot and it is obvious that while some of the roots do grow through, many of the roots stop at the edge of the peat pots. I also don’t know how long it takes the peat pots to disintegrate.

One of my problems with them is they topple over very easily because they are more narrow at the bottom than the top. I am always spilling them.  I was excited to try them and received a very large bag of them for free from a very nice and generous person in my neighborhood. I do not know why she was giving them away, maybe they ended up not being her preference, the same as they are not mine.

I don’t want to discourage everyone from using peat pots. They may be great, depending on a person’s needs, where they live, or maybe the peat pots just work really well for others. My transition from my soil block/peat plugs experience to peat pots did not go well. First, I live in a fairly humid client. It rains a lot which raises the humidity. It also rains often, so the moisture often doesn’t leave the air. On top of that, I use a small room for my seedlings and try to keep the seedlings warm, so the humidity stays higher in the room. Previously, I was very successful keeping seeds very moist until germinating. I then cut down the watering a little, but I typically kept them well watered. A lot of water must have evaporated from the soil, because I didn’t have any problems with too much moisture.

With peat pots it has been a very different experience. They seem to suck up and retain as much moisture as they can and hold the moisture in. I also have a problem with mold growing on the peat pots. My soil will be perfectly fine, and the peat pots will get mold.

For my first seeds, I used purchased soils and mixed them together. I made sure the flats were nice and sterile. The seeds germinated beautifully, just as they have in the past. Most of my seedlings germinate in 2-5 days, even seeds that are expected to take much longer to germinate. When the seedlings were very small they looked great. The problem is, after germination, the peat pots retained much more water than I was used to and I had a damping off problem. I hadn’t had a problem with damping off before so I didn’t know what the problem was and it took me a while to identify it.

I discovered damping off is a soil-borne fungal disease that affects seeds and new seedlings. I had the biggest problem with my lettuce and my onions. Apparently, older plants can handle the fungus but seeds and seedlings often can’t.

My lettuce starts with damping off fungus

Onion starts with damping off

I am in no way saying that the peat pots caused the damping off. It was a combination of over-watering, high humidity, likely non-sterile soil, too much water retention, and not enough air circulation. Although, I think that the peat pots retained too much water, I wasn’t ready to give up on them.

Of course what did I do next? I over-corrected. I have always thought that the store-bought soil would be sterile and I will never rely on that again. This time I was very careful about sterilizing the soil before planting. I cut down watering dramatically.  My tomatoes, which were growing pretty well in sterilized soil with a lot of moisture, started to suffer after I cut down on the watering.  Fortunately and unfortunately, the main plant that was highly impacted from under-watering was the tomatoes. Ho hum, my tomato seedlings will not be that great this year and I think it is too late in the season to start more. I am still hanging on to them though.

Before cutting down on my watering. The tomatoes are up front.

After under-watering the tomato plants

I think these are the worst tomato seedlings I have ever grown, except for the spring I got very sick and I couldn’t care for the plants at all (which amazingly the tomatoes still grew).

I am still adjusting to the watering them properly. I am optimistic that I can find the happy medium. As much as I want to rush to the store and purchase the peat plugs which have always been fool-proof for me, I have resisted.

The next succession of lettuce, looking better than the last. These have suffered from under watering also. I am hardening them off to plant outside this week. I am sure they will be relieved to no longer be under my watering care.

A big problem with the peat pots, even with sterilized soil and much less watering, is that I still see mold. They either dry out so much that the plant is unhappy, or they are moist enough that they mold. From what I have read, this mold shouldn’t impact the health of the plants. I just really don’t like growing mold. Additionally, the pots that are surrounded by other pots in the middle of the tray don’t seem to dry out.

Mold #1

Mold #2

Since my first couple of plantings, I have improved, but I still find it challenging to determine how much moisture the pot retains. I still continue to try, and I still have a large number of peat pots that I haven’t used yet.

It would be a shame to waste all of these new peat pots

I feel like I should be determined and figure out how to make them work. I wonder, is this particular brand of peat pots not sterile?

Has anyone else had a similar experience with peat pots? What is your preference of seed growing pot material?



[Soil block image credit: Flickr, other images are ©Garden4Dinner]

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