Learn Spanish (Latin America): Pulverizando el helecho a menudo, evitas hojas secas. - If you spray the fern often, you prevent dry leaves.

In Spanish, a gerund (ending in -ando or -iendo) can be used on its own to set up a condition, replacing a full si (if) clause. Saying Pulverizando el helecho is a concise way of saying Si pulverizas el helecho. This structure is very common in manuals, tips, and general advice.

Does pulverizar really mean "to spray"? I thought it meant "to pulverize" or destroy.

It can mean "to pulverize" into dust, but in gardening and household contexts, pulverizar (along with rociar) is the standard verb for misting or spraying a liquid using a spray bottle.

Why is evitar translated here as "prevent" instead of "avoid"?

The verb evitar covers both meanings. While English distinguishes between avoiding a thing (staying away from it) and preventing an event (stopping it from happening), Spanish uses evitar for both concepts. Context tells us you are preventing the leaves from becoming dry.

Why use the present tense evitas in the result clause instead of the future tense?

Using the present tense makes the statement a general rule or a universal truth: whenever you do X, Y happens. You absolutely could use the future tense and say evitarás (you will prevent), but that would sound slightly more like a specific prediction about your particular plant rather than general gardening advice.