Hi
I start my seedlings on a bench outside and I am having trouble with some of the potting mixes that have replaced peat moss with compost up to 60% in the mix. They are also using less or no perlite.
The seedling initially grow , but then turn yellow and die. The media is heavy and wet.
I think the mix is heavier because the compost does not dry as fast as peat moss and there isn't enough perlite for drainage.
I water my seedlings and potted plants every day. Is that too much with a compost based potting mix?
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applestar
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Did you mean compost or coco coir?
It seems to me 60% compost would be too much for seed starting mix. And some kind of drainage/inert ingredient should be present?
There is a member who uses a large % compost, maybe even 100% -- I seem to remember, but it really depends on HOW the compost was made and its level of "finishedness", doesn't it?
I use no more than 1/3 compost, more likely 1/4 in the seed starting mix... Let's say combined with approximately 1/2 garden soil and 1/4 sand. So what you have could possibly be too rich, especially for some plants.
In any case, watering should be done on case by case basis and not strictly on a schedule like "every day" -- this would depend on the environment and vigor of the seedling growth. Your basic "touch the surface with finger test" may be the best way to determine if they need watering.
...Almost certainly, watering schedule for seedling trays would be different from established potted plants.
It seems to me 60% compost would be too much for seed starting mix. And some kind of drainage/inert ingredient should be present?
There is a member who uses a large % compost, maybe even 100% -- I seem to remember, but it really depends on HOW the compost was made and its level of "finishedness", doesn't it?
I use no more than 1/3 compost, more likely 1/4 in the seed starting mix... Let's say combined with approximately 1/2 garden soil and 1/4 sand. So what you have could possibly be too rich, especially for some plants.
In any case, watering should be done on case by case basis and not strictly on a schedule like "every day" -- this would depend on the environment and vigor of the seedling growth. Your basic "touch the surface with finger test" may be the best way to determine if they need watering.
...Almost certainly, watering schedule for seedling trays would be different from established potted plants.
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rainbowgardener
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I start all my seedlings in boxes with the soil about 4 inches deep. This allows me to water less and have the roots dig deeper into the soil! I layer mine with garden or even compost at the bottom 2 inches. the top two inches are strained mix of several bought soils like composted manure top soil and a seed starting mix.
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All three mixed together and strained makes my seedlings happy with a array of what they need! I can water my seedlings once or twice a week. I move my plants when they are several inches up to 6 inches high espeially the tomatoes. I beleve in straining the top 1 or two inches of the mixes to get the huge parts out of the mix. The result of the strainiing I use the big stuff at the bottom of my next container!. Soggy is bad for seedlings.
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Add some spagnam or sand to your mix! if you are planting in flats use the bigger cubes. less is more if the results are better! The only thing I plant directly in flats are vine crops that I plantin the garden a week after they come up! Some cole crops grow well in flats also but I can plant 5 dozen cole crops in boxes fast and transfer directly to the garden since the small roots plant nicely! Boxes with deep soil mixes are easier to maintain with better results and can be seperated and moved to cold frames as the outside temps get warmer . boxes allow more seeds to be planted to get them started and move as the weather warms! I even mix several seeds in one box like cabbage a s lettuce or marigolds with alot of other seeds!
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All three mixed together and strained makes my seedlings happy with a array of what they need! I can water my seedlings once or twice a week. I move my plants when they are several inches up to 6 inches high espeially the tomatoes. I beleve in straining the top 1 or two inches of the mixes to get the huge parts out of the mix. The result of the strainiing I use the big stuff at the bottom of my next container!. Soggy is bad for seedlings.
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Add some spagnam or sand to your mix! if you are planting in flats use the bigger cubes. less is more if the results are better! The only thing I plant directly in flats are vine crops that I plantin the garden a week after they come up! Some cole crops grow well in flats also but I can plant 5 dozen cole crops in boxes fast and transfer directly to the garden since the small roots plant nicely! Boxes with deep soil mixes are easier to maintain with better results and can be seperated and moved to cold frames as the outside temps get warmer . boxes allow more seeds to be planted to get them started and move as the weather warms! I even mix several seeds in one box like cabbage a s lettuce or marigolds with alot of other seeds!
Hi, Iamafan! It's wonderful you can start your seeds outside right now! Must be gorgeous, sunny weather! 
If you find that your medium is holding water in the bottom of the cells but drying out on top due to the sunshine/wind you could try just misting the tops every day or so with a small spay bottle full of plain water (or later, compost tea.) That way the top is not getting hard and crusty and the bottoms get a chance to dry out a bit. Then just water as you regularly would every few days in stead of ever day. It will take some extra time, but it should help you out with the current batch of seeds germing.
If you find that your medium is holding water in the bottom of the cells but drying out on top due to the sunshine/wind you could try just misting the tops every day or so with a small spay bottle full of plain water (or later, compost tea.) That way the top is not getting hard and crusty and the bottoms get a chance to dry out a bit. Then just water as you regularly would every few days in stead of ever day. It will take some extra time, but it should help you out with the current batch of seeds germing.
I have changed the potting mix I was using ( Super soil ) to MG when I run out of perlite. It works better. I also made a mistake once and got garden soil instead of potting soil and that might have been a problem with some of my seedling mixes.
The surface of the small pots do dry out with the sun and wind and the seedlings wilt, but the mix itself was holding on to too much water.
Thanks for the advice. I now check the soil to see if it needs water first.
Instead of just watering by habit, I found that some things can go a day or two without water and others can't so, I do more spot watering now. It only takes a couple of minutes to check the plants and in the end it saves both time and water.
The surface of the small pots do dry out with the sun and wind and the seedlings wilt, but the mix itself was holding on to too much water.
Thanks for the advice. I now check the soil to see if it needs water first.
Instead of just watering by habit, I found that some things can go a day or two without water and others can't so, I do more spot watering now. It only takes a couple of minutes to check the plants and in the end it saves both time and water.
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Ohio Tiller
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rainbowgardener
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