I'm experimenting with container growing. I am a complete beginner, so please be patient with my newbie questions.
I've got some young tomato and potato plants, and some onions and cabbages growing in small pots indoors. Getting ready to plant them in larger pots outdoors. I also sowed some leeks and carrots, but they aren't looking good so far.
What kind of soil should I use for planting?
I've got some bags of "potting compost" (contains peat) which is described as being good for container growing, and some multi-purpose compost" which is described as being good for growing vegetables. Should I just use one or other of these? A mixture of the two?
Here's the particular brand I've got.
https://www.homebase.co.uk/en/homebaseuk ... 50l-402080
https://www.homebase.co.uk/en/homebaseuk ... 20l-402074
Anything I should add to the mix? I understand that plants need traces of minerals from rock. Does the compost have all the needed minerals? Should I add a little gravel or sand to the mix?
I understand too that plants need certain bacteria in the soil for growth. Does the compost have the correct ones already? Maybe I should add a few scoops of soil from the garden?
What about perlite? It's supposed to increase water retention and aeration. Is this needed?
Should I add fertilizer? How about plant food? I've seen potato food sold in pellets, and tomato food in liquid. Should I add some of these?
How about water-retaining crystals? Are these useful? I heard they are good for preventing over-watering. Is that correct?
The potting compost looks to be something like peat moss with some fertilizer. The other one does not have enough information to say what is in it.
I would still treat them as peat moss or compost
For my potting mixes I would use
2 part peat moss
2 part perlite
1 or 2 handfuls of vermicompost in a five gallon bucket.
2-4 tbl osmocote or nutracote per 5 gallon bucket.
Your mix has only got a little fertilizer to start plants off, the osmocote will release for 3-6 months depending on temperature. Nutracote is similar to osmocote, but it is more expensive. It is not temperature sensitive and there is a type 200 which will be good for about 6 months, the type 100 is good for about 3 months.
I still have to supplement the heavy feeders like tomatoes with side dressings of fertilizer. I like a slow N fertilizer and numbers less than 10 so I don't burn plants. (I tend to over do things). I like to use citrus food because it contains micros but you can use any complete fertilizer. I don't have much luck with bulbs in my acidic garden. They do better in the alkaline plots that are nitrogen poor. I am going to try them in pots and see if I have better luck. I have to figure out the soil mix and fertilizer for them. I grow green onions in pots without a problem but bunching onions are grown for the tops not the bulbs. I know that the problem in my garden is that it is nitrogen rich.
Potting soil is usually processed so that it does not contain weed seeds or many soil bacteria. Adding a couple of handfuls of finished fresh compost will provide starter bacteria but you can also add a couple of handfuls of soil to do the same thing. I don't like soil in pots because you never know what is in it. Nematodes are common here and that is why I plant heirloom tomatoes in clean pots and potting soil off the ground. I don't use the ground tools for the pots when I put them together to avoid contamination. I don't reuse potting soil unless it has been steam sterilized and mostly it goes into the yard. Soil in pots makes the pots heavy and we don't really like to sterilize dirt.
Some people do not have a problem planting in pure compost. I do. Compost holds a lot of water. In a humid wet climate my plants will drown in the rainy season. 50/50 peatlite drains really well and dries fast. It means I have to water more in summer but they will survive the rainy season better. Peat moss is not usually used alone as it does hold on to water and it will pack down. Compost always packs down without aeration.
Water polymers are useful only if you have total control of watering and you don't over water. They don't hurt the plants in summer, but you have to use more water because the beads will suck up the water and hold it too. In the rainy season the water beads can be disastrous. They will swell up and bubble out of the soil in a gelatinous mess and drown the plants.
If you want better water management try SIP containers.
I would still treat them as peat moss or compost
For my potting mixes I would use
2 part peat moss
2 part perlite
1 or 2 handfuls of vermicompost in a five gallon bucket.
2-4 tbl osmocote or nutracote per 5 gallon bucket.
Your mix has only got a little fertilizer to start plants off, the osmocote will release for 3-6 months depending on temperature. Nutracote is similar to osmocote, but it is more expensive. It is not temperature sensitive and there is a type 200 which will be good for about 6 months, the type 100 is good for about 3 months.
I still have to supplement the heavy feeders like tomatoes with side dressings of fertilizer. I like a slow N fertilizer and numbers less than 10 so I don't burn plants. (I tend to over do things). I like to use citrus food because it contains micros but you can use any complete fertilizer. I don't have much luck with bulbs in my acidic garden. They do better in the alkaline plots that are nitrogen poor. I am going to try them in pots and see if I have better luck. I have to figure out the soil mix and fertilizer for them. I grow green onions in pots without a problem but bunching onions are grown for the tops not the bulbs. I know that the problem in my garden is that it is nitrogen rich.
Potting soil is usually processed so that it does not contain weed seeds or many soil bacteria. Adding a couple of handfuls of finished fresh compost will provide starter bacteria but you can also add a couple of handfuls of soil to do the same thing. I don't like soil in pots because you never know what is in it. Nematodes are common here and that is why I plant heirloom tomatoes in clean pots and potting soil off the ground. I don't use the ground tools for the pots when I put them together to avoid contamination. I don't reuse potting soil unless it has been steam sterilized and mostly it goes into the yard. Soil in pots makes the pots heavy and we don't really like to sterilize dirt.
Some people do not have a problem planting in pure compost. I do. Compost holds a lot of water. In a humid wet climate my plants will drown in the rainy season. 50/50 peatlite drains really well and dries fast. It means I have to water more in summer but they will survive the rainy season better. Peat moss is not usually used alone as it does hold on to water and it will pack down. Compost always packs down without aeration.
Water polymers are useful only if you have total control of watering and you don't over water. They don't hurt the plants in summer, but you have to use more water because the beads will suck up the water and hold it too. In the rainy season the water beads can be disastrous. They will swell up and bubble out of the soil in a gelatinous mess and drown the plants.
If you want better water management try SIP containers.
-
pepperhead212
- Super Green Thumb
- Posts: 2878
- Joined: Wed Oct 15, 2014 1:52 pm
- Location: Woodbury NJ Zone 7a/7b
An SIP is a sub-irrigated planter, which has a reservoir of water underneath the growing medium, which is wicked up, as needed, into the soil. The best known brand is Earthbox, which used to have a good forum, but I think that the new owners let it lapse. You can find a lot of info on youtube:
https://www.youtube.com/results?search_ ... hbox+setup
And here is a thread with a lot of input:
viewtopic.php?f=21&t=60946
I have 21 large SIPs - 10 homemade from 18 gal tubs, and 11 original EBs. I also have 12 homemade bucket SIPs. The plants grow so well in them that certain plants (Eggplants, Cucumbers, and Okra) will only grow in SIPs, and grow less plants, as well.
For these, as well as regular containers, the best way to water is to install some drip emitters on timers. In the heat of summer, it is amazing how fast they can dry out, and you wouldn't want to be hand watering all of them! lol
The medium used in SIPs can't be much compost - it doesn't "wick" that well. Peat is the best, with coir a distant second, but only because it eventually decomposes into compost, and can't be used over and over (though I do use about 10-15% coir, and it hasn't seemed to bother it). You need some perlite, for aeration, as with any soil, though only about 20% here. And worm castings are a compost type addition, that doesn't seem to compromise the wicking (there were countless threads on these things on that defunct earthbox forum), and some people would add up to 25%, but I only add about 10%. I use Promix BX, with myco, as the base, adding a little bit of these other things.
Here are some photos of my SIPs from past years:
https://s24.photobucket.com/user/pepperh ... t=3&page=1
https://www.youtube.com/results?search_ ... hbox+setup
And here is a thread with a lot of input:
viewtopic.php?f=21&t=60946
I have 21 large SIPs - 10 homemade from 18 gal tubs, and 11 original EBs. I also have 12 homemade bucket SIPs. The plants grow so well in them that certain plants (Eggplants, Cucumbers, and Okra) will only grow in SIPs, and grow less plants, as well.
For these, as well as regular containers, the best way to water is to install some drip emitters on timers. In the heat of summer, it is amazing how fast they can dry out, and you wouldn't want to be hand watering all of them! lol
The medium used in SIPs can't be much compost - it doesn't "wick" that well. Peat is the best, with coir a distant second, but only because it eventually decomposes into compost, and can't be used over and over (though I do use about 10-15% coir, and it hasn't seemed to bother it). You need some perlite, for aeration, as with any soil, though only about 20% here. And worm castings are a compost type addition, that doesn't seem to compromise the wicking (there were countless threads on these things on that defunct earthbox forum), and some people would add up to 25%, but I only add about 10%. I use Promix BX, with myco, as the base, adding a little bit of these other things.
Here are some photos of my SIPs from past years:
https://s24.photobucket.com/user/pepperh ... t=3&page=1