Expert: Christopher Littrell - 6/24/2007

Question
QUESTION: Hi. I have a Drosera Capensis plant that has been doing really well on my window sill. I keep it in standing water so it can have its bog environment and its been great for about 4 months. I had 2 separate occasions where it grew flowers and produced seeds and now, all of a sudden, the ends of all the, what do you call them...the ends on the plant are turning black. Even on ones that have not opened fully. The new flower stem is turning black also and it's only a few inches high. The buds are all black and they weren't even close to blooming. Also, the little dew drops are gone. Have I done something wrong? Please tell my my plant isn't dying. Thank you so much for your help.

ANSWER: Hi Rachel,

We will need to do a bit of detective work to find out what is occurring with your sundew. Whenever new growth is affected the same as older leaves something systematic is occurring in the environment to harm the entire plant.

What kind of water do you give the plant? Hard water can build up minerals in the soil that are harmful to the plant. It would take weeks or months to finally begin killing a carnivorous plant.

What kind of soil, chemicals, and additives do you use on or near the plant? Fertilizer, copper based fungicides, soap based fungicides and insecticides, and anything that adds mineral salts or nutrients to the soil can poison carnivorous plants slowly over the course of months. If you bought it from a hardware store, it might have been exposed to fertilizer before you even bought it.

A few things to try would be to completely repot the plant in fresh soil after cleaning off the roots. Sphagnum peat moss from the dry bales, not the bags, and clean, regular perlite in a 50/50 mix would do. Make sure none of the ingredients have fertilizer added and make sure the bale of moss says something like "premium Canadian sphagnum peat" on it.

After repotting, supply the plant with a tray of water with about an inch or so of fresh rain, reverse osmosis, or distilled water, making sure that none of the water you use is regular tap water or says drinking water on the bottle as those contain minerals.

Sundews like water, but make sure you keep the water level at or less than 1/4 of the pot in level so that the roots do not drown or rot. I have never seen a Cape sundew experience root rot from too much water, but they typically enjoy only the bottom of the container in water and their soil constantly moist, but not waterlogged.

Since the plant has flowered and consistently grown well in a particular window for months, we can rule out problems with light and humidity since it sounds like you have not moved the plant around much. Cape sundews are tropical perennials that should stay strong for years indoors in a sunny window.

Send me a follow up if you can elaborate on the water, soil, and any chemicals in the environment your plant is in so we can find the problem if it is not already covered here.

I hope your plant recovers,

Christopher


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

QUESTION: Thank you so much for your detailed answer. I purchased this plant from a home and garden show. The soil was what they had it in. I never replanted it, so I'm not sure about the soil it is in.

As soon as you mentioned the water I knew that that had to be a main problem. I just gave it tap water. I did exactly what you said about washing the roots (the roots still look good and healthy), and completely replanting it, since it couldn't hurt. I checked the soil and it said everything you said, right down to the Canadian sphagnum peat. I put every glass dish outside to catch the little bit of rain we're getting today so it will have fresh rain water. I am going to go to the store and buy a couple gallons of distilled water too.

I have another Drosera plant that I bought at Lowe's and now I'm going to do the same for that one so hopefully, the same thing doesn't happen to it.

Again, thank you so much. I didn't want to lose my favorite plant. Hopefully this will help it continue to grow for me and catch those pesky fruit flies.

Oh, would you recommend cutting off the stems that have black on them including the new growth with the black? Or should I just leave it alone?

Rachel

Answer
Hello Rachel,

You can cut off anything that is blackened or dried out on your sundew. Leave any parts that are still green and keep a lookout for new growth. If the roots looked healthy enough, then maybe the plant will pull through, but sometimes the damage is irreparable. Hopefully, you caught it in time. Cape sundews are basically considered a weed, as you noticed how prolific they are with seed production, so hopefully you saved some seeds to propagate more plants from just in case.

The main thing to remember about carnivorous plants is that almost without exception, they hate anything that alters the Ph acidity of their soil. They adapted to nutrient poor bogs so their roots are unable to handle any changes in acidity levels that would allow bacterial action and nitrogen formation in the soil. It begins burning and rotting their roots.

Just keep up the good care and hopefully the D. capensis will make it, they are often tougher than they look. Repot your sundews once a year, any time is fine for tropicals as they do not go dormant, and keep those impurities out of their soil.

Christopher