Where’s The Beef?
Houseplants don’t need to eat as much as humans do, or as often. But they do need to
eat – fertilizer that is. And they should only be fed when they are actively
growing. They should never be fed during the slow-growing season, when they are
stressed, infested with pests or as a way to force them to grow faster.
Over-fertilization in houseplants can be quite a problem; many well-meaning
individuals often over-feed their plants in an attempt to encourage vigorous growth. This
is a big no-no. Too much of a good thing quickly leads to ailments: spindly and stunted
growth, burned or dry leaf margins, scorched growth or loss of lower leaves, wilted and
even dead plants. Excess fertilizer also causes problems in the root system – damaging
the newly developing root hairs. Roots turn brown, become soft or rot. All this in turn
delays plant growth. So in truth, the vigorous growth that you hoped to accomplish has
backfired and you’re left with a lethargic and ailing plant – the things you intended
to improve.
If that’s not enough to deter you from being frugal with the feeding, maybe this will:
A weakened plant is more susceptible to attack from insects and diseases!
No, not that...
Don’t over-feed; too much fertilizer is toxic to your plants!
When and How Much?
Chances are that if you are following fertilizer directions according to the label
of your product as though it’s a plant bible, you are probably over-fertilizing! If you
are also following advice word for word in your plant books about when
and how much to fertilize each specific plant in your home, you are also over-fertilizing.
Huh?
You must bear in mind that plants manufacture their own food through photosynthesis
and require fertilizer only as a supplement. With light being the most important
element in their food process, there are many other considerations attached to that
when it comes to feeding.
Here are just a few (of many) things to consider when feeding:
- Plants should only be fed when they are actively growing (usually spring & summer)
- Reduce or eliminate fertilization during the resting period
- Plants growing in lower light conditions need less feeding
- Plants in brighter areas growing rapidly require more feeding
- Plants growing under artificial lights don’t experience seasonal light changes and may require more feeding year-round
- Feeding frequency is also determined by the age and vitality of a plant
I’m a little guarded when it comes to feeding my plants. I always dilute further than
what is recommended and sometimes choose not to feed particular plants. I believe
it’s easier to repeat a weak application than to reverse the damage done by a heavy
one. The consequences of excess fertilizer – damaged leaves and roots, stunted growth
and possible plant death – are an unnecessary (and self-inflicted) evil chore that
I’d rather not be dealing with. Along with watered-down applications, I also don’t
feed very often. As a general rule – unless my plant shows signs that it needs more
food – I usually feed once a month in spring and summer and not at all during the
winter. My plants are my signal; they will tell me whether the fertilizer is helping
or harming and whether they need it or not.
What the heck do those numbers mean?
I was just as confused – until recently – as anyone else about the numbers on fertilizer products. 10-20-10; 20-20-20; 5-10-5; 10-10-10. I never bothered trying to find out what it all means even though it’s actually very important.
The three numbers marked on fertilizers indicate percentages of three very important elements needed for optimal plant growth – nitrogen (N), phosphorus (P) and potassium (K) - in that order. A mixture of 20-20-20 is often better for green foliage plants while one of 10-20-10 is better for flowering plants which require less nitrogen but more phosphorus.
The numbers on fertilizers are there to give you information about the product so that you can determine what best to use. Whether you want to stimulate growth, enhance flowering or just keep a plant healthy, those numbers will help you choose appropirately.
Let’s Talk Nutrition
There are roughly 16 important nutrients that your plants need for optimum growth. If deprived of essential nutrients over a substantial period of time, plants will suffer just as animals suffer from vitamin and mineral deficiencies.
The 16 essential elements are combinations of chemicals required in different amounts and are referred to as macro (large) nutrients and micro (small) nutrients.
Nine essential macronutrients:
- Carbon (C) - what most of the plant is made of
- Oxygen (O) - necessary for cellular respiration
- Nitrogen (N) – promotes development of leaves
- Calcium (Ca) – helps promote new root and shoot growth
- Potassium (K) – helps plant resist disease
- Phosphorus (P) – aids in growth of roots
- Sulfur (S) – contributes to leaf color
- Magnesium (Mg) – contributes to leaf color and helps absorb sunlight
- Hydrogen (H) - necessary for building sugars and building the plant
Seven essential micronutrients:
- Copper (Cu) - important for photosynthesis
- Boron (B) - important in sugar transport, cell division, and synthesizing certain enzymes
- Zinc (Zn) - plants require zinc because it activates enzymes
- Molybdenum (Mo) - olybdenum is a cofactor to enzymes important in building amino acids
- Iron (Fe) - necessary for photosynthesis; present as an enzyme cofactor in plants
- Chlorine (Cl) - affects photsynthesis and root growth in certain plants
- Manganese (Mn) - necessary for building the chloroplasts
* At least 96% of a plant’s weight is hydrogen, oxygen, and carbon but these elements are not included in fertilizers because they are available to plants from the air and water *
* The other macro and micro nutrients compose the remaining 4% of the plant’s weight. Even though 4% seems like a relatively small number to worry about, it does play an important role in a plant’s optimal growth just as the bulky 96% does *
Enough information for one day?
Let’s move on...
Feeding Your Hydroculture Clan
Food is important to all plants. It helps them develop healthy roots, striking leaves and vibrant flowers. Your hydroculture group is no exception to this important part of plant care. No matter what type of set-up you choose – hydro kits, glass, plastic – you must supply your plants with nutrients when they require it.
There are hydroponic fertilizers available that provide plants with an appropriate balance of necessary nutrients. This well-adjusted solution is the ‘crème de la crème’ of fertilizers for your hydroculture plants. You might not be able to find it readily at department stores you visit regularly but you will most likely find it at local greenhouses and garden centers. Of course, it’s always available to you at hydroponics shops if you have any near you. 
Hydroponic nutrients are available in dried or liquid form. You will most likely need to mix them with water since most of them come in concentrated form. In hydroculture kits you also have the option of using a slow release nutrient (loose granules or gelled disk that is placed at the bottom of the hydroculture water reservoir every six months). Starter kits are also frequently accompanied by slow-release nutrient formula.
I just recently picked up a hydroponic fertilizer. Up until now I have been using a commercial houseplant fertilizer like all the rest of my soil-growing houseplant comrades – Miracle Gro. It’s a liquid nutrient that I do not use exactly as recommended on the bottle since my plants are not grown in soil. I dilute it to 1/10th the strength. Miracle Gro advises that I add 10 – 20 drops per liter, I add 1 or 2.
I have been very pleased with the performance of Miracle Gro up until now. Since I am only beginning to use a hydroponic fertilizer, I can’t really tell you what the difference between the two is – if any. In the upcoming weeks I will feed my plants exclusively with the hydroponic product to get a significant idea of its effect on my plants. Same? Better? I will see. When enough time has passed, I will share the results with you on this website.
In the meantime, remember to feed your hydroculture plants the nutrients and minerals it requires. Those vital elements help your plant make proper use of the sugars – food – that are produced during photosynthesis.
Keep them healthy, keep them happy. You’ll be rewarded.
Return to the Hydro Log main page
