Fertilizing your indoor plants is important because as you water them you wash away nutrients from the soil over time. Those nutrients need to be replenished to keep our plants happy and healthy! You could easily spend days researching fertilizer and still be confused, luckily I did that for you and hopefully I’ve done a good job simplifying it so you can make the best decision for you and for your plants!
When choosing a fertilizer what you are looking for is the N-P-K ratio. N for Nitrogen, P for Phosphorus & K for Potassium are the key Macronutrients your plant needs. A complete fertilizer also contains Micronutrients, like calcium, magnesium, sulfur and several others. Organic fertilizers usually come from plant waste (compost), animal waste (manure) or powdered minerals like bone meal.
General/ all purpose indoor fertilizers will work for most of your leafy house plants but flowering plants like orchids, african violets and jasmine need a fertilizer higher in phosphorus. Cactus and succulents tend to prefer a fertilizer with less nitrogen.
Nitrogen – for healthy foliage growth
Plants take in lots of nitrogen – allowing them to absorb energy from the light (photosynthesis) which encourages the production of protein which then becomes plant tissue. It’s an essential nutrient for leafy growth. More leaves = more sun absorption = bigger, stronger & more vibrant plants!
Phosphorus – for healthier roots, flowers & fruits
This element helps plants produce, store and move energy from the roots to the leaves and flowers. It promotes a strong root system, healthier fruits & flowers and a longer bloom time.
Potassium (K) – for overall health & resilience
Although plant’s don’t naturally produce any potassium their overall health, growth & longevity rely on it. It builds a strong disease resistance & stress response and regulates water and co2 intake.
Types of Fertilizer;
Liquid– Every to every other watering
Liquid fertilizer comes in a concentrated form that you dilute and incorporate into your normal watering routine making it really easy to remember and perfect for beginners! With this method you get complete control over how much or little you feed your plants and you get a really even distribution of food in the soil.
Spike/ Tablet – Monthly to bi monthly
Just like the name suggests this fertilizer comes in a spike or tablet form that gets pressed into the soil and dissolves over time. It is super low maintenance, all you have to do is replenish it once a month, it’s not messy and there is no risk of smell like the liquid method. The fertilizer is activated by water so as long as you are keeping your plants hydrated you won’t have to worry about it. The downside is that you get less control over how much food your plants are getting and it’s not as evenly distributed meaning the roots may stretch out and get tangles looking for the nutrients.
Slow Release/ Granular – Once or twice during growing season
This method is really great for people who are really busy or forgetful… All you have to do is sprinkle the granules on the soil once during a growing season. The liquid nutrients are encapsulated in a coating which breaks down slowly and releases the nutrients in low doses over a long period of time. It’s the easiest way to fertilize but don’t recommend it because it’s usually a synthetic/ chemical based formula.
Things to consider;
You only need to fertilize plants when they are actively growing, for most that means spring and summer. If you live in a tropical climate you can fertilize year round.
Start fertilizing 4-8 weeks before the last frost and stop fertilizing 4-8 weeks before the first frost
Overwhelming a plant with nutrients could do more harm than good, so start slow on the first few doses, dilute your fertilizer up to 2x more than the directions recommend – too much can burn the leaves, reduce the ability for plant roots to uptake nutrients or even kill the plant.
Just like in the spring, before the first frost and before your plants go dormant you can dilute your fertilizer more for the last few applications before you stop completely.
If your plant has been recently repotted you can skip fertilizing for a handful of waterings and if you are planning to repot you can fertilize up until that point.
If the soil is bone dry water it liberally the day before fertilizing.
If your plant is showing signs of stress, hold off on fertilizing until it looks a little happier.
Low light plants, cactus and succulents have adapted to live in low nutrient soil and can go years without being fertilized but it doesn’t hurt to give them a low dose or two at the beginning of the growing season!