I've recently repotted my spider plant (chlorophytum comosum) to a slightly bigger pot with better drainage. I potted it in a mix of normal potting soil and perlite to aid drainage. I recently noticed that some of the tips in the lowest leaves have burnt. This is something that hadn't happened before.

My questions:

  • Could the perlite in the new mix have caused this?
  • Should I repot the plant into fresh soil?
  • Is this condition a threat to the health of my plant?

I have uploaded an album on Imgur with the pictures: https://i.sstatic.net/0tnaT.jpg

  • Do you still have the bag of potting soil? Look for added fertilizers. Have you added any fertilizer and if so what and how much and how long ago. Definitely need your pictures otherwise we are assuming too much!
    – stormy
    Commented Apr 15, 2017 at 23:40
  • Picture would illustrate what seems to go wrong
    – J. Chomel
    Commented Apr 16, 2017 at 7:09
  • Here's a link: imgur.com/a/8MexW. I do realise it's not as big a problem as I made it sound, on second thought. The soil mix I used was a mash-up of what I had available, so a bit of this cactus soil and this universal soil. ⅓ to ½ of the final mix is perlite. The plant never had tip burn however and I saw it happen after coming back from a 2-week holiday after repotting.
    – kettlepot
    Commented Apr 16, 2017 at 9:59
  • I read online that it's possible to rebalance the pH of the soil by adding some compounds (maybe lye?) to counteract the effect of the fluoride (?) contained in the perlite. Is this a valid solution? How would I go about measuring the current pH level?
    – kettlepot
    Commented Apr 16, 2017 at 10:03

1 Answer 1

  1. Perlite has a pH of about 7-7.5 and doesn't change soil pH. This source says perlite has zero CEC (Cation Exchange Capacity), so I doubt fluoride or other elements in perlite interact with pH.
  2. Transplanting again would increase stress in plants, so I wouldn't do it, more so because spiderplant is not a choosey plant about soil.
  3. I don't think there is a risk to the health of your plant, more likely the browning tips are related to unregular watering schedule, since you said you went on a holiday.

Soil pH is measured with a pH meter. This type is unreliable and I think you should avoid it: enter image description here

Edit: Lye is used to change pH for in vitro growing medium and maybe it is used to change soil pH also, but I haven't heard of this method. I know that calcium carbonate or calcium hydroxide can be used for neutralising acidic soil, if you still want to.

  • Thanks! Do you have a suggestion for the correct interval at which to water this plant? You're correct that I maybe didn't water it enough recently.
    – kettlepot
    Commented Apr 17, 2017 at 15:56
  • I don't know what is the correct interval for watering this plant. All my plants have different watering schedules based on species, season and sunny/cloudy days. I guess you'll have to figure it out by trial and error.
    – Alina
    Commented Apr 17, 2017 at 16:00
  • Do you have a suggestion for what to do if I see the tips keep browning?
    – kettlepot
    Commented Apr 19, 2017 at 21:41
  • It does seem like underwatering was a source of the issue, however.
    – kettlepot
    Commented Apr 19, 2017 at 21:43
  • Leaves getting brown and falling are a normal thing for perennials as long as new leaves emerge faster than the old fall. If I were you, I wouldn't make a decision until new type of symptoms appear.
    – Alina
    Commented Apr 20, 2017 at 5:48

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