Smart Gardening 2020: Saying 'Good-bye' to a plant

Scale on a lemon stem

Sometimes, a plant challenges even the best of our efforts as gardeners. I recently bid farewell to my five year-old Meyer lemon tree.

I love Meyer lemons, and this tree had produced some fruit, and the beautiful fragrant flowers that bloomed in winter were almost as good. The small tree (about 5 ft tall) resided outside on my deck in the summer and indoors under a grow light in the winter. This tree has also been the subject of many WCCO Smart Garden discussions and text messages.

What happened to my Meyer lemon tree

A few years ago, I discovered scale on the lemon tree. Scale reside on all parts of the plant and are very hard to see - especially on a large plant like a citrus tree. Scale suck the plant juices and produce a sticky, clear excrement kindly referred to as "honeydew" (I called it "honey glue" as it is impossible to remove off of the plant, the pot, the floor, furniture).

I pursued the scale first by hand-picking the insects -  a time-consuming, labor-intensive process of scratching the flat, tan scale off with my fingernail (ugh). Did I mention citrus have thorns?

Hand-picking was not enough, so I added spraying with products like Neem oil, insecticidal soap and horticultural oil. I finally resorted to the systemic pesticide imidacloprid in granular form (the tree only bloomed for me in winter when it was indoors, so no threat to bees).

Last year, I went so far as to hand paint neem oil on every surface of the plant to suffocate the scale.

The problems that multiplied...

While my efforts knocked down the scale population temporarily, the scale still persisted. On a recent warm winter day, I rolled the lemon tree outdoors onto the deck and dowsed it with neem oil, turning over the leaf surfaces and blanketing the plant.

When I checked the plant later, the news was worse: fine webbing had become visible meaning yet another pest had arrived: spidermites. Spidermites are far more mobile than scale, and I was immediately concerned they would infest my other plants. The mites were the last straw and the plant went into the compost.

Do you have a challenging plant, too? 

Scale young and old on a lemon leaf

Giving up on plants can be tough.  Plants can have sentimental value. Or you've invested a lot of time
and effort into care. There's also the matter of  what I call "gardener's pride" and the bragging rights associated with being able to successfully grow these more challenging plants.

You reach a point where you have to consider the risk factor of infecting of other plants, cost of treatment, time, and whether the plant's performance justifies the real estate it occupies.

I also take a pragmatic approach when it comes to chucking plants: more room for something new! Will I get a new fruit tree? Maybe, but not right away. I think I'll enjoy the extra room and take my time finding a new and exciting replacement.

Anyone have a suggestion? Email me: jweisenhorn@umn.edu

-- Julie Weisenhorn, Extension Educator, Horticulture