From our perspective, the most common reason for these holes is that we are being used as a food source. Insects, particularly caterpillars, are the usual culprits. They have mandibles designed for chewing, and our leaves are a prime source of nutrition for them and their growing larvae. You might not see them, as many are nocturnal or expertly camouflaged, but the damage is their calling card. Species like the cabbage looper, cutworms, or slugs and snails (which are mollusks, not insects) find our broad, succulent leaves particularly delicious. We try to defend ourselves by producing bitter-tasting or mildly toxic secondary metabolites, but some pests have evolved a tolerance to our specific chemical defenses.
Sometimes, the holes begin not from the outside, but from within. Certain fungal or bacterial pathogens can infect our leaf tissue. They start by creating small spots or lesions where the tissue dies. As the infection progresses, this dead tissue can dry up and fall out, leaving behind a hole that often has a yellow or brown "halo" around it. This is different from the clean, chewed edges left by insects. From our point of view, this is a systemic issue. It often means the conditions around our roots and leaves are too damp, allowing these pathogens to thrive. Poor air circulation and overhead watering are common contributors to this problem, creating an environment where we are more vulnerable to disease.
While less common, physical and environmental factors can also damage our leaves. Hail, strong wind-driven rain, or even accidental physical damage from gardening tools can punch holes through our delicate tissues. Furthermore, if our caretaker applies a fertilizer that is too strong or is not properly diluted, it can cause "fertilizer burn." This doesn't create a hole in the traditional sense but can cause large, scorched sections of the leaf to die and eventually tear away, creating irregular holes. From our perspective, this is a case of too much of a good thing; the high concentration of salts in the fertilizer literally draws the water out of our cells, causing severe stress and tissue death.
Please understand that a few holes are not a catastrophe for us. We are resilient beings. We can tolerate a certain level of leaf damage without a significant impact on our overall health or ability to photosynthesize. In fact, we are constantly trying to outgrow the damage. We may channel our energy into producing new, undamaged leaves to compensate for the lost photosynthetic capacity of the injured ones. Our goal is always survival and reproduction. While the holes are unsightly from a human perspective, they are often just a minor setback in our life cycle, a testament to the ongoing struggle between plant and pest in the garden ecosystem.
