If a plant looks to lack vigor, growth looks stunted, flowering is poor the first question to ask is if the plant is getting all the need nutritional requirements. This goes beyond food, examine the lighting and watering.
How long have you owned the plant? If you've had the plant for over a year what did the plant look like last years at this time. This is why we keep some type of journal.
Are any pests noticeable? IF there are did the plant get them last year at this time.
NEXT Step
Does the plant have any seasonal needs or issues. Dropping of leaves, blooming, etc.
NEXT Question?
What's the age of the plant? This goes beyond how long the owner has had it in their possession. Is the plant a seedling? Seedlings, small cloned plants and cuttings may be much different than a fully grown mature plant.
NEXT
If all signs point to no problems it's time to dig deeper. Here's where I pull the plant out of the pot if it is growing in a pot. Examine the root system? Is it healthy? Are the roots actively growing? Does the plant need repotting? Is the soil compacted?
Without a healthy root system your plants are fighting an uphill battle!
NEXT
If the roots look good it's probably time to pull out the magnifying glass. The magnifying glass is a plant doctors stethoscope. Getting a close up is like an x-ray. A whole new world can be found living on leaves.
Check the undersides of the leaves for critters, it's their campground. Look for spider mites, scale, mealy bugs, aphids, chewing insects and more. I recommend using neem oil as a natural pesticide for controlling plant pest.
Learning how you can diagnose any plant problems you may encounter is not that difficult. Take one step at a time - ask "What's Changed" or "What's Different" then eliminate the possibilities and throw in a dash of common sense. Soon you'll be the one giving out house plant care tips.
