PlantKeep every new plant 2–4 weeks away from your collection and check it weekly with a 10× lens. That is long enough for hidden eggs to hatch into pests you can see.
Why two to four weeks
At the moment of purchase most pest problems are invisible: spider mite eggs are 0.1 mm spheres on the leaf underside, mealybug eggs sit inside cottony sacs in leaf axils, thrips eggs are inserted into leaf tissue, and fungus gnat larvae live under the soil surface. Their cycles set the length of quarantine. Spider mites go from egg to adult in 7–10 days in warm rooms, thrips in roughly 2–3 weeks, and fungus gnats in 3–4 weeks. Two to four weeks lets at least one generation reveal itself.
Commercial growers also treat plants on a preventive schedule, and those treatments can hold pests below visible levels for a while after the plant leaves the nursery. A clean-looking plant on day one is not yet a clean plant.
Inspect before you pay
Two minutes at the shop saves weeks of treatment later. Take a small hand lens or use your phone camera zoomed in, and look where pests hide rather than at the side of the plant displayed to customers.
- Leaf undersides along the midrib: pale stippling, moving specks or fine webbing (spider mites).
- Leaf axils, stem joints and under leaf sheaths: white cottony tufts (mealybugs) or brown bumps that scrape off (scale).
- Silvery streaks with tiny black dots of excrement on leaves: thrips.
- Sticky honeydew, or black sooty mould on the leaves below it.
- Tap the pot: small black flies lifting off the surface are fungus gnats.
- If the shop allows, slide the root ball out: roots should be firm and pale, not brown, mushy or sour-smelling.
Set up the quarantine spot
Use a separate room if you can; if not, keep at least a couple of metres between the newcomer and your other plants, as spider mites drift on air currents and walk across touching leaves. The spot still needs appropriate light and temperature, or you will confuse stress symptoms with disease. Put a yellow sticky card in the pot to monitor gnats and thrips.
On arrival, rinse the foliage under a lukewarm shower (with the pot surface covered) and wipe large leaves on both sides. This removes a good share of any mobile pests and dust. Water and handle the quarantined plant last in your routine, and wash your hands and tools afterwards.
Weekly checks, and what to do if you find something
Once a week, go over the plant with a 10× lens, focusing on new growth, leaf undersides and leaf axils, and count the sticky card. If you find something, identify it before you reach for a spray, then follow the specific treatment for that pest. A few mealybugs can be dabbed off with a cotton swab dipped in 70% isopropyl alcohol (test on one leaf first); spider mites, thrips and gnats need repeated treatments timed to their life cycles.
Restart the quarantine clock from the last treatment: the plant joins the collection only after two or three clean weekly checks in a row. A plant that is heavily infested with mealybugs or thrips is often better returned or bagged and discarded than nursed alongside a healthy collection.
Let it settle before changing its care
A move from a nursery greenhouse to a living room is a big drop in light and humidity, and some leaf drop is normal, especially in fiddle-leaf fig (Ficus lyrata) and weeping fig (Ficus benjamina), which shed leaves after almost any change. Do not repot in the first 3–4 weeks unless the plant is waterlogged or badly root-bound; use that time to learn how quickly its existing pot dries. Nursery mixes are often dense and peat-heavy and dry more slowly than you would expect.
Hold off on fertilizer too. Most nursery plants arrive with enough controlled-release feed in the mix to last several weeks.
