imafan26
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Posts: 13962
Joined: Tue Jan 01, 2013 8:32 am
Location: Hawaii, zone 12a 587 ft elev.

Re: Why can't garden soil be used as potting soil?

I made a mistake once and put garden soil in the container instead of potting soil. The bags looked alike so it really was an honest mistake. The first thing I noticed was the lack of perlite. The second was how coarse it was and how heavy it was. I tried it anyway and the pots did not drain well, the water pooled on top and when the pots dried it contracted and the plants stayed wet for too long, eventually they yellowed and died. I guess it did not have any fertilizer either. In fact it acted a lot like compost.

I usually make a custom mix because I water a lot and I live in an area where seasonal rains can come all day every day for a week so I need to have a year round mix that drains well and dries fast. It means in the dry season, (which should be now but it is not) I have to water more or double pot.

I in the wet season I use 50/50 peat moss and perlite a handful or two of vermicast if I have it in a 5 gallon bucket + a couple of tablespoons of osmocote as a starter fertilizer.
In the dry season if the plants are drying too fast I use a 60/40 mix of peat moss and perlite, but I will usually only use it on plants I plan to keep in pots only temporarily. I am never going to get around to repotting before the rains come again so it is better for me to water more when it is dry and double pot rather than have the plants drown when the rainy season comes.
I have extra holes drilled in plastic pots so they drain better, double potting blocks the holes, I just have to remove the outer pot before they drown.
For succulents and orchids which cannot tolerate wet feet, I plant in terra cotta pots, baskets, pots with extra holes in them, and media is usually black or red cinders or for some orchids and bromeliads no media at all. Eventually the orchids will attach to a porous pot and they can be watered every day that way. In the rainforest they don't grow in pots, they grow in trees with their roots hanging out in the air so even though it rains every day in the forest, the roots have ample time to dry.

The succulents pose a bigger problem for me so I have to choose the ones that can take more water and keep them where none of the sprinklers can reach them. If it rains for a long time, day and night, I have to bring them in to the patio so they can dry out. I keep my lavender by the patio under the eaves so when it rains it does not get rained on directly and the water coming off the roof falls outside of where the pots are. Lavender leaves will turn black and the plants can die if they get too much water. I am having problems with my lavender. I used to grow them better. It may be my mix. I am usuing a higher percentage of perlite to keep them drier but I am still having some of them die Anybody have a good soil mix for lavender?

tomc
Super Green Thumb
Posts: 2661
Joined: Sun Apr 10, 2011 2:52 am
Location: SE-OH USA Zone 6-A

PR, a mix of half sand and half potting soil would be better. Its air that most long term potted plants lack. I can direct you to bonsai growers who are using 1/2 chicken grit, and 1/2 pine bark mulch with perfectly happy trees.



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