I got a recent e-mail from a reader asking me what to look for when shopping for healthy houseplants. I've decided to post the response here in the hopes that what I do can be of use to someone else.
Houseplants can be bought in a variety of places now and I'm not above picking one up in a retail setting outside of a greenhouse. I've purchased houseplants from drug stores (oddly enough Cacti & Succulents), garden centers, greenhouses and even from a street peddler. Houseplants are the same the difference is in the care that they are receiving and the conditions they are being housed in.
When I walk into a greenhouse I look around and take in that first impression. The first thing I usually note is the smell, does it smell fresh or is the air stagnant? Does it have a "clean" smell or does it smell like someone has gone overboard with chemicals? The second thing I usually notice is the how the plants all look together. At first glance the plants as a group should look lush and the leaves are upright and perky. The benches and the floor of the greenhouse should be free of garbage and look generally well maintained.
I take a walk through the whole area and look at plants that I'm not particularly interested in. I do that because often times when I'm looking for one specific plant I put on blinders and don't notice other things. On a recent trip to a greenhouse I was looking to buy a Pony Tail Palm but I decided not to buy it at that location when I noticed that the Corn Plants had a particularly bad case of mealy bugs. Even after I'd made the decision not to buy a plant there I looked around some more and found an even greater infestation of mealy bugs on the Birds Nest Ferns just a few rows over.
Generally if I don't find any obvious signs of houseplant pests I'll continue the plant examination by picking it up and looking at the undersides of the leaves just to double check for any signs of pests. I avoid plants that have brown tips,broken or torn leaves or broken stems. The top of the plant should be free of brown or yellowing leaves and the pot should be clean of any decaying plant matter where bugs may congregate. I'll continue the plant inspection and look for cobwebs and spider mites. Spider mites are small and can escape detection with the naked eye. But if you notice any tiny red specks moving that's probably a spider mite.
Next I'll flip the plant over and remove the pot to examine the roots. They should be evenly distributed and the root ball should be free of any bad odors. The soil should look fresh and not have any algae growth on it- that's a sign of too much watering, similarly I avoid plants where there is an excess buildup of minerals on the surface or on the lip of the pot. If a plant has been there long enough to collect algae or mineral deposits from the water/fertilizers it's probably not a good candidate to take home.
I try to avoid purchasing any plant that looks root-bound, you can tell if a plant is root-bound because the roots have begun to grow in a circular pattern around the diameter of the pot in search of more soil and nutrients. Take this opportunity to look again for any signs of bugs in the soil and if you find any pass on the plant. It may seem like overkill to look in so many spaces for bugs but it's better to be safe than sorry.
If the retailer and plant pass inspection and you decide to make a purchase a houseplant make sure to quarantine it from your other plants when you get home until you're satisfied you didn't bring any bugs home. Provide adequate light and humidity for your plant with a humidity tray to help it get through the shock of being moved from the greenhouse to your home. As you get more experience with plants you'll develop your own set of rules and you may even find that you break your rules every so often for that special plant you've been after.
Don't forget to take the time to get to know the people who work in the places you will buy your plants from. They know when the new plants come in, when they may go on sale or who to talk to for a discount on a plant. If something should go wrong with your plant instead of just taking it to the cashier at the customer service desk you can go directly to the people you bought it from and see if the two of you can determine where you went wrong so it doesn't happen with the next plant.