Quarantine Zone – Bringing in New Plants

The COVID-19 pandemic of 2020-2021 has left me like many people across the world with germy paranoia, the tendency to wield bleach-based household cleaners as a ward against evil, and a lot of time to closely observe my surroundings whether I want to or not.

The increased time inside made me register just how many pests were feasting joyously on my plants. I had, up until then, drive-by shot neem oil or insecticidal soap on infected specimens, never fully eradicating infections. Thrips mortally wounded my Monstera deliciosa and weakened my red Anthurium and beloved Peperomia argyreia. Spider mites windsurfed from my Norfolk Island Pine (Araucaria heterophylla) to my rubber tree (Ficus elastica). God-forsaken scale spread their armored bodies across the leaves of my majesty palms (Ravenea rivularis) like summer vacationers on the French Riviera. Lastly, I noticed ominous clouds of fungus gnats within leftover bags of potting mix.

A spirit of utter ruthlessness overtook me. Whereas in the Before Time, I might coddle a failing plant, now casualties were propagated if possible and then tossed into the trash, totally bypassing my compost bin.  Two leaves of Mama Monstera were used to create Baby Groot I & II. Mother plant to the trash. My attempts to salvage Peperomia failed as cuttings rotted before they rooted. To the trash. Anthurium. Trash. Ravenea. Trash. There was no room for parasites in my self-contained Eden.

[Note: I really tried with the palms and even used systemic insecticide, not realizing that the Bonide I bought works on SOFT SCALE, but not ARMORED SCALE. Grrrr argggh.]

Then I arguably went a little bit loco. I came across Kew Gardens’ Living Collections Strategic Plan one day when searching for goodness knows what, probably recipes for container mixes. In it they described their biosecurity protocols. At a time when I was already wearing masks, gloves, and eye protection before a lot of the general US public had gotten the memo, I was perhaps a bit obsessed with infection prevention. Doesn’t help that in a past life I was a candidate for an infectious disease epidemiology doctorate.

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A few grow lights were relocated to the “Quarantine Room” (the unfinished home office/spare guest room). New plants were kept apart from the rest of the pack for 3-4 weeks (separate shelf or separate room) and preemptively treated with insecticidal soap. I tried growing plants from seed. Hands were washed between plants. Old plant pots were bleached. Plants got regular spa treatments, i.e. leaves showered and wiped down. I bought those overpriced blue and yellow sticky strips to monitor pest populations. I mixed vermicompost into my container mixes (research suggests that in addition to promoting plant growth, the organisms with the worm compost can suppress certain common plant pests). I did everything, but use beneficial insects. I’m saving that stage of warfare for this winter when spider mites take advantage of the dry air to wreak their red-bodied havoc.

My Current Quarantine/Pest Management Practices

In summer 2021, I’m feeling less frantic about my quarantine and pest management practices. Below, I’ve summarized what I do in 13 steps. I have 230 plants at the moment with a goal of 400-500 for the Involucrata project, so what I need to do to keep pests to a manageable level is likely far more intense than for someone with a smaller collection. But these are best practices that I follow with varying levels of compliance depending on how busy or lazy I am. Sadly, I ALWAYS pay for laziness with having to spend more time dealing with the issue later.

1. Carefully inspect plants before buying. 
2. Avoid unhealthy and unhappy plants as these are more susceptible to pests.
3. Once home, spray and wipe down all the leaves. The wipedown is not viable for plants like fern, so they just get a good shower.
4. Pre-treat with insecticidal soap or horticultural oil or neem oil. CAVEAT: DO NOT USE NEEM OR OIL-BASED PRODUCTS ON SUCCULENTS!
5. Place newbies in quarantine (i.e. a separate room or area or shelf) for 2-6 weeks and monitor on a regular basis. A different room is ideal because spider mites are little windsurfers. A different bench, at least 6 feet apart, is workable. Less than this is suboptimal, but you do what you can.
6. Use dedicated tools for quarantined plants.
7. Sterilize tools with flame or alcohol or bleach solution before use.
8. Wash your hands between plants (especially infected ones obviously).
9. Keep your plants healthy so they can repel pests themselves.
10. Treat emerging pest problems IMMEDIATELY. 
11. Monitor emerging pest problems with sticky traps.
12. Unless you have a compost heap that gets good and hot, chuck out dead plants, leaf litter, and prunings from infected plants
13. Don’t reuse soil between different plants. 

This fall, I want to learn more about beneficial insects. Summer Rayne Oakes, amateur botanist and trained entomologist, waxes lyrical about them all the time.

People who create live vivariums have an even more involved quarantine process as their plants need to not only be free of pests, but also of fertilizers and pesticides for the health of the amphibia or other sensitive creatures in their enclosures. See New England Herpetoculture’s plant processing guidelines for more information.

What do you do to keep your plants pest-free? Let me know in the comments.

Recommended Reading:

Colorado State University Houseplant Course on Managing Houseplant Pests 5.595

Managing Houseplant Pests – 5.595

UK National Trust & Washington State University’s Turning Over a Clean Leaf:

Click to access NurseryPoster_FINAL2.pdf