Question
QUESTION: Hello,

I have germinated some tropical sundew seeds this past month (capensis pink variety I believe).  They germinated well and I have teeny sprouts growing.  The problem is that mold keeps growing in the pot as well.  I have been removing the mold from the surface as it grows, and that seemed to be working, but the mold is recurring faster and each time there is more and more of it.  I don't know what I can use to kill the mold or prevent it from coming and not harm the little sprouts.  Before I planted the seeds I had sprayed the growing medium with a sulfur mixture.  I'm not sure if that would work in this situation.  Also, I'm growing them indoors, so I'd prefer something that doesn't have harsh smell/fumes.

Thanks!

ANSWER: Hi Kristine,

Yes mold is a perennial problem, so it's not something that you treat just once.  Unfortunately, you have to spray each time you see it pop up.  The initial sulfur spray worked initially, but it's effectiveness wore off.  Spray again with the sulfur.  You may need to go a bit heavier if the mold keeps coming back.  

Another product to use is Neem oil.  Safer?brand makes a prepared solution of it.  It's also effective with mold, but it also smells very nasty.  So use it as a last resort.

Yes you definitely want to control the mold as much as possible since it can affect the health of your plants and your health as well.  If possible, place your pot next to a very sunny windowsill.  Ultraviolet light will also kill off some of the mold spores.  

Let me know if you need further assistance.

Good growing!
Jacob Farin

---------- FOLLOW-UP ----------

QUESTION: Thanks for your advice.  I'm glad I can use the sulfur again, but I'm still a bit unsure of how it works.  Does it kill mold that is already growing, or prevent mold from growing in the first place?  I've always thought it was just the latter.

Also, when you say that I may need to use it a bit heavier if the mold keeps coming back, I'm wondering if there is a level that would be too much for the sprouts.  They are still pretty tiny, just with three leaves each, and maybe just a teeny bit bigger than 1/8" tall.

Thanks again!  

Answer
Sulfur kills mold by making the soil acidic.  Acids both inhibit and kill mold growth.  Sulfur is just slower acting since it has to react chemically with the soil to create the acidic compounds.  Neem oil is much faster acting, but it breaks down quickly.

I sometimes see first-time growers be very tentative when spraying, so I never know if they are applying a therapeutic dosage.  That's why I recommend to simply apply a bit heavier if it comes back.  Because my plants are my livelihood, I tend to be aggressive with the treatment to stop the fungus completely.

Sure there may be a point in which the soil becomes too engorged with sulfur that it inhibits your seedlings, but at least I haven't seen my seedlings be adversely affected with heavy applications of fungicide.

As a grower, you have to weigh the risk of not applying enough and seeing the mold return, perhaps with greater resilience, or apply heavy to stop the mold and perhaps risk injuring the plants.  Moreover, if the mold keeps coming back, is it because the applications were not sufficient, or is the environment too laden with mold spores to successfully grow carnivorous plants?

Fortunately Cape sundews are easy to come by and rather inexpensive.  If you are new to growing carnivorous plants, you might have an easier time growing your plant and controlling the mold with an adult plant than with seedlings.  Adult plants are much more resilient and more forgiving of Neem oil and sulfur than seedlings, just as adult humans are more tolerant of large doses of aspirin and other medications than children.  So this is something for you to consider.

Also make sure your plants are getting direct sunlight.  This will help control the mold.

Good growing!
Jacob Farin