Euphorbia cutting held in place by glued-on pebble mulch. Photo: FeathersOfJade, reddit.com
Question: Last month, I bought a plant in a pot covered with pebbles that were actually glued into place. I’m having a hard time knowing when and how much I should water the plant, as I have no idea when it’s nearly dry. What should I do?
Answer: You should remove the pebble top-dressing.
This type of glued-on decoration is designed to better hold soil into place when plants travel from the grower to the store to your home. It’s often used on plants that look mature, but are in fact poorly rooted. By coating the soil in a layer of pebbles soaked in nontoxic glue (one hopes!), both the wobbly plant and its soil will be held firmly in place, so even if the plant tips over during transit, no harm is done. It’s when you get the plant home that troubles begin.
There are spaces between the pebbles, so you can water. But as you mentioned, you can neither see nor touch the soil underneath, making proper watering almost impossible.
The usual method for testing whether a plant needs watering, that is, sinking a finger into the growing mix to feel if it’s dry, is impossible. The best you can do is pour water in until some drains out through the drainage hole at the bottom and hope you’re doing it right. Then you can guesstimate as to when the soil has reached that “nearly dry” state when you need to water again.
Lifting the pot and weighing it in your hand can help: it will be lighter when the soil is dry than moist. Still, even this method works best when you can see the soil (and touch it as well) as you get to know the plant’s needs. It’s very hard to judge the initial state of humidity of a plant when you have no access to the soil.
Reduced Air Circulation
Also, a glued-on top dressing reduces air circulation to the base of the plant and its roots. That can also contribute to rot.
Pots Without Drainage Holes
To add insult to injury, sometimes these plants are sold in pots without a drainage hole. There is really no way of telling when such plants should be watered. I doubt if any plants sold in such a barbarous condition survive more than a few months. Really, any grower who does this should be ashamed of themselves!
Strangling Your Plant
Here’s another thought. Many plants have stems that expand in width as they grow. They’ll eventually be strangled to death by the mulch layer, as it doesn’t allow them to expand.
Other plants produce offsets over time. They can’t if their base is surrounded with a layer of glued-on pebbles.
For all the above reasons, you should remove the pebbles ASAP.
Loose Pebbles as Top-Dressing
Loose pebbles and other decorative stones covering the soil in a pot are a different story entirely. In those cases, you can easily check on watering needs by removing a pebble or two and touching the soil. Many succulent and bonsai growers always the potting mix with a top-dressing of small pebbles as a matter of course … they just don’t glue it into place!
Struggling to Remove the Pebbles
Removing the glued-on pebble mulch is not easy. Try using a flat-edge screwdriver or butter knife, slipping it between the pot and the mulch to try and pry it free from the pot. If so, you might be able to break off a piece or break it in half. Still, it’s hard to do this without causing some damage to the plant.
I found the easiest way to get the mulch off was to take a hammer and smash the pot. Then you can grip the pebble layer and, bending it up and down, break it off, freeing the plant.
Of course, then you have to repot.
The only time I bought a plant with a glued-on pebble mulch was a beautiful crested euphorbia (Euphorbia lactea cristata cv) I paid $45 for, more than I’ve ever paid for such a small plant. When I got it home, I smashed the pot in order to remove the mulch … only to discover it wasn’t even rooted. Yes, I had unwittingly bought an unrooted cutting essentially glued into its pot! Talk about a rip-off!
I never was able to get the cutting to root, even after repotting into a smaller pot (to better control the watering). It eventually rotted away. I suspect many “glued-in plants” are also unrooted cuttings: it’s a sneaky way for the grower to shave many months off production time. And many succulent cuttings can live for months, even more than a year, without roots, living off their reserves, so when it eventually dies, the buyer would likely think the loss of the plant was their fault.
Do note that I did manage to get a reimbursement for the unrooted cutting.
Pebble mulch glued into place: yet another horticultural rip-off!