In last week's blog post, we were encouraging plant parents to give their plants some fertilizer as we have now crossed over the threshold into the season of active plant growth.
Easy enough, right? Follow the package instructions, make the magic potion, administer and voila! Happy plant!
As you have probably guessed, there's a teensy bit more to it than that. Here we've put together some advice on how to fertilize so that you can be a more attentive plant parent.
1. Fertilize when your plants are actively producing new growth
Alright, you've probably heard this one! But a common thread you will see throughout this list is avoidance of over-fertilization! In this endeavor, it's important to make sure your plant is a) wanting to use the nutrients you're giving it and b) prepared to absorb them. These conditions change throughout the annual cycle! As a rule, it's a good idea not to fertilize during late autumn and winter, when light levels are low. Plants are not growing and will not use the nutrients, leading to root-damaging build up.
2. Introduce Fertilizer slowly in the spring and taper out in the fall
When you want to start giving your plants their vitamins, take it slow and try to do it gradually. Start the spring season off by diluting the fertilizer significantly more than the label directions suggests, and increase the concentration little by little with each feeding until you reach the concentration of fertilizer you would like to use during peak growing season (we suggest always diluting down a little bit from the package instructions, and never exceed the concentrations suggested). Conversely, try decreasing the strength of your fertilizer as the days get shorter in the fall.
3. Make sure that the soil is moist before fertilizing
A plant that is thirsty may take up more nutrients than they can use before their tissues are adequately hydrated. This over-inundation with salts could destroy the plant tissues. Keep in mind that severely dried out soil may even become hydrophobic! Give your plants a drink and thoroughly soak the soil. This will hydrate the plant and prepare them to soak up the minerals in the fertilizer.
4. Know Your Plant's N-P-K Needs
Fertilizers are used to provide plants with the three prevailing macronutrients. These are Nitrogen (N), Phosphorus (P) and Potassium (K). Look at any fertilizer label and seek out three hyphenated numbers - these will tell you the ratio of Nitrogen to Phosphorus to Potassium: the N-P-K ratio or fertilizer analysis. Most houseplants are easily fed with a balanced houseplant food, which will reflect even nutrient-levels in their N-P-K ratio, such as 10-10-10, 6-5-6, 8-7-6, and so on. Some will like a high phosphorous houseplant food (useful for flowering houseplants) or a high-nitrogen plant food (useful for foliage plants), but balanced fertilizers are called all-purpose plant foods for good reason, and these are usually your best bet for feeding your plants.
5. FLUSH OUT EXCESS SALTS
Typically, plants will not take up every last bit of fertilizer, and the leftover salts may build up. You may actually see the white deposits on the soil, pot or on the plant itself. This happens particularly in the top inch or so of soil, as water evaporates more quickly from this area, leaving behind the accumulated salts. As we have already mentioned, these salts can be harmful to the plant and may destroy its root tissues, thereby interfering with the plant's ability to take up nutrients and water. You can flush the plant of these salts by double watering - or thoroughly drenching the plant multiple times, allowing excess water to drain for 30 minutes between drenchings.
1. Fertilize If the Plant is adjusting to a new place
As strong as the desire is to see your plant grow wildly and with abandon in a new space, don't fertilize plants that are recently purchased or or recently moved. The task of adjusting to new conditions can be a stressful ordeal for a plant (just like it is for humans!). It's hard enough to transition without the additional pressure of producing new growth. Give your plant a rest, and give it the water it needs to adjust and reach a settled stasis. When you see that the plant is healthy and ready to grow, then you can fertilize.
2. Fertilize soon after repotting in fertilizer-rich soil
Most potting soils actually include some starter fertilizer, so it's best to allow plants to use up these nutrients before giving them additional food. About six weeks is a good estimate of how long to wait before they will have adequately depleted the soil, but several factors will influence the rate at which the plants deplete the fertilizer in their soil, including light, temperature, frequency of watering, size of root mass and overall growth rate.
3. substitute FERTILIZER FOR Correct Growing Conditions (enough water, light)
Don't fertilize at the first sign of plant weakness. It's easy to panic and to want a quick fix when your plants look like they're struggling, but it's better to take a moment to observe their growing conditions and listen to their needs. If your plant is looking wilted, discolored or anemic, ask yourself, is your plant getting the right amount of light? The right amount of water? Is it in a breezy hallway with fluctuating temperatures? Does it have adequate drainage in its pot? There are many possible factors that you should rule out before giving your plant the juice. Do a quick google search to find out what your plant's ideal growing conditions are. Fertilizing will not bring a plant hungry for light back to life, and instead may in fact be the nail in the coffin.
More is not better! If you've gotten this far in the list, you understand that this is very important. Remember that fertilizer is not a life-or-death situation. Plants get their energy from light, not fertilizer. The elements that plants absolutely need to survive are oxygen, hydrogen and carbon - all of which are provided from air and water. Over-feeding will lead to root burn and weaker plant longevity.
All told, there is so much fascinating science behind about plant nutrient absorption and the function of fertilizers, so keep an eye out for future in-depth posts on fertilizing! In the meantime, we hope this is a helpful handful of hints for those of you who are thinking of giving your plants a nutrient boost.
Was there anything we missed? Anything you'd like to know more about fertilizers? Have you lost a beloved plant to root burn? Let us know in the comments!
welcome to field notes, niche’s weekly blog that covers all things plants. we’ve got answers to all your questions, suggestions for that black thumb, and diy planting solutions for every home. we write about what you want to know, so if you have a subject that you want us to cover, email us : firstname.lastname@example.org.