In a word--yes. My father washed his house w/ TSP before re-painting and all of their boxwoods and holly bushes (foundation plantings) have dead spots where the stuff hit. Some of their 30+-y/o boxwoods are now dead, although I don't know for sure that the TSP is what did it. (I'm not there much so I don't know what else might have gotten them.)

I would cover w/ plastic any plants that you want to protect. Of course, w/ it being summer, don't leave the plastic on the plant any longer than you have to so you don't cook them. I would wait a little while after TSP has been applied and rinsed, though, for any droplets to hit the plastic instead of your plants. If he chooses to use the TSP on a sunny day, maybe he could do it at the end of the day so you could cover your plants overnight while the house dries? Just an idea.

If any plant that you value is accidentally hit w/ the stuff, rinse it well w/ water immediately. My guess is that run-off into the grass would kill the grass, unless you then take the hose and water down those areas very well. (Goal being to dilute and maybe even get rid of the TSP on the grass.)

TSP is trisodium phosphate, and is a really great cleaner, but dreadful for humans and plants. This is very alkaline, and if you've got acid-loving plants nearby, you're going to have to work, as Alex z7 said, to keep them safe. I would add to his/her instructions, to water your plants very deeply just before you cover them up and the TSP gets going.

Please also make sure that you and your husband have eye protection and thick, chemical-use gloves before you open up the box of TSP.

You are almost certainly going to lose some plants, if only some grass; all you can do is minimize the damage.

Good luck with it - this is a big job you're taking on!

Joan

Good luck w/ your project. I totally agree, TSP is a great product for cleaning but is nasty, potentially harmful stuff. Take a look at the box for TSP for the warnings to see what it can do. yech....

I will be interested in knowing if the HD can recommend anything safer.

We are putting vinyl siding on our house and my plan is to use some dish soap in water to help clean it. It may not be as "good" as TSP, but it will be safer for me and for my plants. Plus, if I am using a pressure washer, I figure that would get the majority of the dirt, anyway.

I'm a firm believer in it's better to be safe than sorry when it comes to anything I care about. My health and my plants definitely qualify as something I care about!

Try the pressure washer without any chemicals....it should clean by itself.

I saw a box of tsp-f I think at one of the paint stores and I think it is made for vegetation. Not sure thou.