This week I stumbled across yet another website offering garden “advice”—hacks to make you a better gardener. This one focused on used tea bags. Yup, did you know that you can reuse those bags to help your garden thrive? Or not…

I picked three hints to highlight from their list of eight, but really, only one was actually realistic. They suggested burying tea bags to hold moisture. Yes, organic matter does help your soil retain moisture, and used tea bags are full of organic matter. But seriously, why not just water your plants, instead of expecting their roots to grow into the tea bag (through that fine mesh).

“Use Old Tea Bags to Add Nutrients to the Soil”

Here’s the claim: “Tea bags contain tannins and other nutrients that will increase the nitrogen level in the soil. They will also provide a bit of food for earthworms that are wonderful for tilling the dirt in your garden.”

Black tea is made from leaves of  Camilia sinensis. Brewed tea contains water plus “tea extract”—a chemical with the composition C₅₀H₅₀N₄O_26. As you can see, there is no P or K, and only a little N. But remember, that’s in the tea.

This website is telling us to fertilize with used tea bags. Yes, there are some tannins, more if you didn’t squeeze the bag when removing it from your cup. But there aren’t enough tannins to make any difference to your plants. Moreover, these tannins (catechin, epicatechin, epicatechin gallate, gallocatechin, epigallocatechin , and epigallocatechin gallat) don’t contain any nitrogen, just carbon, oxygen, and hydrogen. Therefore, they have no value as fertilizer, as plants get these nutrients from the air.

I suppose that the soggy leaves do provide the soil with a modicum of organic matter. But considering the number of tea bags you’d have to save to significantly amend your soil, it just doesn’t seem worth the hassle. Besides, what about the actual bags? I find they don’t break down quickly, although it depends on the type of bag material used. And who wants to bother tearing the bags open to dump out the leaves? Unless you have a kitchen compost bucket, where you can simply toss the bags as you use them, I’d just dump them in the trash.

 “Use Old Tea Bags to Keep Weeds at Bay”

Here’s the claim: “Biodegradable tea bags not only provide your garden with nutrients, but they will also discourage the growth of weeds. A wonderful non-toxic (and basically free!) option for keeping weeds out of your garden.”

So, they supposedly encourage the growth of your desirable plants, but discourage the growth of weeds. Tell me—how do the tea bags know the difference? And what if I consider dandelions weeds, but my neighbor wants to grow them for the greens? Will tea bags kill mine but fertilize hers?

“Use Old Tea Bags to Grow Seedlings”

Here’s the claim: “Tea bags are great plant food, so it only makes sense that they’d be the perfect vessel to grow seedlings. Plus, since they were steeped in boiling hot water, they are sterile, which makes them great for growing healthy plants.”

You already know that tea bags are not great plant food. A good seed-starting medium should contain not just a trace of nitrogen, but also phosphorus and potassium, plus some trace minerals. Yes, newly germinated seeds don’t need fertilizer immediately, only as they start to get their first true leaves (as opposed to the cotyledons). If you sow seeds on tea bags, you’d have to plant them as soon as they sprout.

In fact, you’d have to for another, more important reason. The tea bags are so small, they can’t provide any space for roots to expand. Only the tiniest of seedlings would fit.

And finally, once you plant them, you’d better hope that the bag itself decomposes quickly, or it will act as a barrier to the roots, keeping them from growing outward into the soil.

Just as egg shells and egg cartons make horrible seed starting containers, so do tea bags.