I wrote the following in an e-mail to the admin, and it was suggested I go ahead and share with the forum, so I'll just copy and paste what I wrote. This is for people looking for more information about watering plants with menstrual blood (or any body fluid for that matter!).
--pasted message below--
First of all, I would like to say that I am researching the purchase of my first menstrual cup and the information on your site has been invaluable. I really appreciate the effort of managing this site, and it's easy to see that many women also find this site useful.
I couldn't help but click on "other uses" for menstrual blood. I didn't even think about watering plants with menstrual blood, and I have to say... it makes sense! However, there are a few caveats which I feel I need to share with you. [...]
I am a wildlife biologist and I wanted people to be aware of a few things before they water their plants with menstrual blood.
The first is the watering of houseplants with blood. Many houseplants are toxic to pets (including common ones such as aloe vera, "money plant" (also called pothos or other names), "mother-in-law tongue" (also called snake plant or other names) and many types of palms). If the pet is usually uninterested in plants, this may not be a problem--but if you pour blood on it, the pet may decide it smells like food after all and might start to nibble on the leaves (as one person wrote in to report). If they start nibbling on the wrong plant, this could result in hefty vet bills... or worse. Here is the ASPCA website listing common houseplants that are toxic and nontoxic to cats dogs and horses: http://www.aspca.org/pet-care/poison-control/plants/
Another concern arises when watering plants outside. Menstrual blood contains anything that is flowing in your blood system at the time of your menstruation. This includes medication! While I would feel uneasy about watering your plants indoors and leaving chemicals behind like ibuprophen, oral birth control, antibiotics, etc., this is a real problem when taken outdoors because of the potential for groundwater contamination. Groundwater contamination is possible no matter where you live. Contamination of this kind is a big problem for the ecosystem and there have been documented detrimental effects on wildlife exposed to elevated estrogen levels from birth control! That's why they tell you to put NuvaRing back in the little foil package it comes in and dispose of in the trash and NOT to flush down the toilet (for example).
It would be good to share this with women who are looking into feeding their plants and want to make an educated decision.
All the best!