6

Four weeks ago, I bought a bag of soil with the label “For In-Door Plants”.

However, I noticed the formation of mold very quickly after I used it:

image of a potted plant with slight mold on the soil

Is it the soil? The watering? Or something else I am doing wrong?

Niall C.
  • 7,199
  • 11
  • 48
  • 77
user2536125
  • 375
  • 1
  • 4
  • 7

2 Answers2

10

The conditions for growing mold are warmth, soil consistently wet, little air movement and undisturbed soil, and the presence of spores to feed on the organic matter present. It is natural to find some spores in potting compost, not a big deal. The plant in the pot (probably Chlorophytum) has fleshy roots and can be allowed to dry down between waterings. So one suggestion is to hold off on the water somewhat, reduce the temperature a bit, expose to gentle breezes and, as you are doing already, keep the surface loose.

Colin Beckingham
  • 19,612
  • 1
  • 12
  • 43
4

This is totally common to have happen with new soil. It must not be sterilized very well or they added organic matter and fungal spores later. Not a problem. Use your fingers to 'fruff' up the top of the soil, might have to do that a couple of times but this fungal growth will stop. Very common when organic matter is added to the soil.

How did you plant your plants in this new soil? Is that pot full of soil or did you put rocks or gravel below the soil and above the drainage hole? If so, you need to redo by turning over, get rocks or gravel out of the bottom completely and re-potting adding more soil. You should only have 1" from the rim to the top of the soil. Do not water too much. Allow to dry a bit and as this is new soil for this plant make sure it gets some water around the roots until it is well established then you can start soaking the soil, allowing it to drain, wait until the top 1" is dry before watering again. Could you take a picture of the ingredients and send?

stormy
  • 40,098
  • 3
  • 31
  • 75
  • Isn't it generally (i.e. always) advisable to cover the bottom of a pot with gravel, expanded clay or something similar for drainage? – dakab Jan 27 '17 at 08:31
  • No. Absolutely a MYTH. Trust me, using rock or gravel at the bottom of your soil only exacerbates soggy soil. You've made a perched water table with small pore spaces above large. All those pores in the soil have to become saturated before the water begins to flow into the large pore spaces. Big no no. All soil, only potting soil in a pot. Nothing between the bottom of the pot and the sterilized potting soil. Get rid of those rocks or whatever below the soil otherwise the drainage is truly compromised. Lift the bottom of the pot off the surface using tiles to improve drainage. – stormy Jan 27 '17 at 08:44
  • @dakab that's a common myth. – Stephie Jan 27 '17 at 08:44
  • 1
    Interesting. I thought it was used to simulate soil horizons on a miniature level, with water-permeable layers—below the soil—ending in a drainage divide. It’s also extensively advised, so I guess people need something more palpable than “trust” or “that’s a myth”. – dakab Jan 27 '17 at 09:53
  • @dakab http://gardening.stackexchange.com/questions/13774/what-is-a-perched-water-table – Graham Chiu Jan 27 '17 at 10:55
  • So by adding stones at the bottom of the pot, all you are doing is raising the perched water table. – Graham Chiu Jan 27 '17 at 11:00
  • Well you might look at it that way but water will drain out of soil easily to go out the hole or even the sides of the pot if the soil is over dry. I would rather go into an 'upside down' perched water table...for pots but it is the same principle. – stormy Jan 28 '17 at 01:12
  • @dakab it is normal to feel that way. So much confusion in any media about any topic. You gotta know that our qualifications on here are as high as one could get in horticulture, soils, entomology, on and on. I am a 3X Master Gardener, Landscape Architect, I taught Plant Materials and Design, Grading and Drainage, Graphics and Design. Fluent in Chemistry Biology, Botany and SOILS as well. I could go on but the rest of us on here are just as if not more versed in this stuff. To dis our answers will only slow you down. TRUST me, grins! – stormy Jan 28 '17 at 01:21
  • I think it is interesting how humans think they can do better than 'nature' without understanding this humongous realm of sciences. Miniature soil profiles???? Grins...love to discuss in detail...later. Smaller pot, just potting soil and raise bottom of pot off table surface to stop the surface tension slowing drainage...no rock or gravel, no other foo foo. Honest injun!! – stormy Jan 28 '17 at 01:25
  • 1
    It’s noteworthy how my relatively neutral, explanatory, thus constructive comment made you feel your answer being “dissed”, which it was *not*. But if you *want* to feel that way: Consider it a reminder that “trust” doesn’t count if you lay it on that thick, implying that producing academic sources would be no big deal for you. There’s indeed no room for more than that in comments, especially when it starts to get “grin”, generalize “humans” or become implicitly [offensive](https://en.wiktionary.org/wiki/honest_injun#Interjection). – dakab Jan 28 '17 at 08:28
  • Excuse me but I meant no such thing. I am blunt sometimes but hey, sorry if my wording came across as being defensive and GRINS offensive. Miniature soil profiles...I was only trying to HELP. I do own the right to pontificate and give experiential advice. I thought my comment was relatively neutral and with a smile or a grin...If you have a problem with my comment let us discuss the specifics, not my writing STYLE. Just be glad you get to deal with my words as me in person might overwhelm. I am not a boring encyclopedia. I really really try to be NORMAL. And nice! – stormy Jan 28 '17 at 23:52