Question
Hello! I recently received a TDS meter, and found out I've been giving my plants water that's 43ppm. I've been collecting it from rainwater, but I'm down to the last 5 gallons, which will last me for a month or so. I also checked my tapwater, and it's 99ppm. We don't have city water, just rain/spring water mix. Can I use the tap water for my plants? I have Sarracenia, VFTs, Nepenthes rafflesiana, temperate and tropical Drosera, one ping, and seeds of various species. Will any of them be affected negatively by the extra hardness of the tapwater? I'm sick of using all that rain water every month, and that's just my plants that are'nt dormant! I'll be using 2-3 times that much in a couple months!

Also, I've been told that all forms of Drosera Binata need a dormancy. I had a giant form that I kinda forced into dormancy, and the only reason I still have that plant is because I took some root cuttings. (The mother plant died)
I've also received some smaller forms in seed form, and I don't want to kill them like I killed the giant! So do they need a dormancy or not, and if they do, how can I take care of them so I don't kill them. As far as I know, I can't keep them outside, since I live in Zone 6,(KY)
and that will kill it I think!

Thank you for your help!
Aslan

Answer
Hi Aslan,

At 99 ppm, your tap water has too much minerals, which would be harmful to your carnivorous plants on a long-term basis.  You could get away with it short-term, for a few months.  Longer than that, however, you will start seeing slower growth and burnt tips.  

If you choose to use your tap water, every month you'll need to top water distilled water and rinse out your water trays.  You'll also need to repot your plants into fresh soil every year, or sooner if you start seeing burnt tips.

Read our e-book in the section about water purity.  There's a technique to supplement your tap water with distilled water.  There are also reverse-osmosis units that you can use.  This can be very cost-effective if you have a large collection of plants.

With Drosera binata, the plant is technically a warm-temperate (also known as sub-tropical).  What this means is that the plant will go dormant if it's exposed to changes in the season.  However, it doesn't require winter dormancy like other temperate plants, such as flytraps and Sarracenia pitcher plants.  It can grow throughout the year if you provide full sun and warm temperatures.  We have many of these plants that grow year after year in our greenhouse.

With that said, this species is also very tolerant of freezing temperatures.  At our nursery, we have a couple of mother plants growing exclusively outdoors (zone 8).  They die back to their roots in winter and re-emerge in spring.  They do this year after year without fail.  A grower in Toronto (zone 4) has one in his outdoor bog garden that survives the winter.  

So you really don't need to force this sundew to go dormant.  Drosera binata ssp. dichotoma tends to go dormant very easily in a windowsill.  The natural drop in daylight hours and temperature will cause it to go dormant.  

Now if your plant died during dormancy, you should check to see if other factors were affecting, such as dehydration and fungal infection.  Those two would be the most common causes of plant death during dormancy.  If you also did the root cuttings right before it went dormant, you may have impaired its ability to survive dormancy.

So this spring, after the risk of frost has passed, grow your plant outdoors in full sun.  In winter, follow our winter precautions as outlined in our e-book.

Good growing!
Jacob Farin