Unless you're in the southern hemisphere, now is not the best time to fertilize. I would wait until at least April to do any pushing for growth.

Thank you for all of the replies!

I live in Northern Florida and I water my succulents roughly every 2-2.5 weeks judging by their soil dryness. I water my coleus more frequently, about 1-1.5 weeks in between waterings also taking in account soil dryness. My parlour Palm I also have on the same routine with the coleus. I try not to let the parlour palms soil get too dry before watering.

Hi Al!

I would love to hear more information! I'm still a beginner when it comes to plants, but I know that I love them to death! Do you recommend I hold off fertilizing them until spring because I'm a beginner?

Hope it's OK to answer even tho' I'm not Al.

No, recommending holding off fertilizing 'til Spring not because you're a beginner, but because as that's when the plant will be in active growth, likely wanting more nutrients & being able to put fertilizer to good use, not while it's in slower Winter growth, which for some plants can be more of a resting period.

Lena

Of course it's alright if you're not Al! I was only responding to his post :)

Thank you so much for the information! I appreciate it. I will wait until spring. I can't wait to see how much they grow in the spring time!

Whether plants are in active growth or growing imperceptibly, they still need the same number of nutrients in the soil, available for uptake, and would prefer them at a ratio as close as possible to that at which they use them. No one goes plant to plant removing the nutrients available to plants growing in the ground when they go dormant or quiescent, and they do just fine.

The reason we're faithfully instructed not to fertilize in the winter is because someone discovered that 99% of hobby growers use soils that are so water-retentive, watering in small sips is the only way to keep from over-watering; but, watering in sips means all the dissolved solids from fertilizer solutions and tapwater accumulate in the soil until the EC/TDS (roughly the salt level) of the soil solution reaches levels so high the plant struggles to take up water, or can't, and dies or looks like it's going to. Their solution: Don't fertilize in the winter.

The problem with that advice is, whether or not one fertilizes, the EC/TDS of the soil solution continues to rise until there is serious trouble ....... unless the soil is flushed regularly, which negates the reason for giving the advice in the first place. Flushing the soil is like hitting the fertilizer 'reset' button, so you're essentially left with a soil devoid of nutrients, so any growth that occurs is far more likely to be abnormal, and the plant may not have nutrients it depends on to keep its systems orderly. MUCH better would be to regularly flush the soil when we water and regularly supply a low dose of nutrients in a favorable ratio. That solves all the issues insofar as supplying appropriate volumes and ratios of nutrients and eliminates having to choose between the lesser of two evils.

I think I've probably provided enough photos of perfectly healthy and happy plants to illustrate that practical application of what I just outlined works very well. OTOH, the many thousands of posts in these forum pages that bear witness to the fact that a large % of hobby growers don't yet understand the triangular relationship between soil choice, watering habits, and nutrition, even after following the oft-repeated instructions to withhold fertilizer in winter, are a pretty good indication that particular path doesn't work so well.

Above, I referenced how difficult it is to advise someone about how to fertilize (doesn't matter what time of the year it is) without having specific information about, at a minimum, soil choice and watering habits. W/o some critical pieces of info, we need to explain ALL the details about fertilizing plants and qualify everything that needs qualification if we want to be perceived as knowledgeable (IOW, almost write a book). "Never fertilize in the winter" along with "Never Fertilize a Sick Plant, when given w/o qualifying the statements are a sure indication the person giving the advice hasn't reasoned through it and is just repeating 'what they heard or read somewhere'.

How would those who think the OSFA advice to suspend fertilizer applications for the winter months rewrite the following: It's difficult to argue with the idea that our focus in supplying supplemental nutrition to our plants should be on ensuring all the nutrients plants normally assimilate from the soil are A) IN the soil and available for uptake at all times, B) in the soil in a favorable ratio - that is to say in a ratio that mimics the ratio at which the plant actually uses the nutrient, C) at a concentration high enough to ensure no nutritional deficiencies, yet still low enough to ensure the plant's ability to take up water, and the nutrients dissolved in that water won't be impeded (by a high concentration of solubles in the soil solution)? And/or, where would you insert "except in winter"?

Al

Without seeing the plants in question it is very hard to advise feeding, especially with MG. I know a lot of people use it, but it in of itself can cause even bigger nutrient deficiencies down the road, it is also highly concentrated. A more natural, lower NPK would probably be better for winter fertilizing.

We don't know whether these plants are suffering, I am assuming they aren't. At least I did not get the feeling that that is the case by the OP. Without proper lighting any growth you push for is going to be leggy, ugly, and can cause a lot of pest problems. Aphids love new growth and coleus is a big attractant for them. There have been studies that point toward the conclusion that plants with more nitrogen are more susceptible to chewing pests like mites and aphids. As I'm typing, I'm watching ants bring aphids in to the plants sitting right next to me, even though there is snow on the ground and they shouldn't be out and about for a few months. I need to do a shower run it seems.

Miracle grow makes a LOT (hundreds) of fertilizers that range in concentrations as low as .5-1-1 (or even .02-.02-.02 if you count MGs version of Spray-N-Grow as a fertilizer) to 10-52-10, and at least a dozen of those NPK %s are labled as "All-Purpose", so it's difficult to know what the OP is getting ready to use. I'm guessing it's 20-20-20, 24-8-16, or 12-4-8, the 3 most popular "All-Purpose" blends.

The NPK %s listed on the packages of fertilizers are actually totally irrelevant to the end concentrations, though there is a greater potential for grower error if the grower is applying fertilizer in slow release granular form. There is no difference when using 24-8-16, 12-4-8, or 9-3-6, because, if we follow package directions the end solutions will be almost exactly the same concentrations of NPK. IOW, you'll be directed to add half as much 24-8-16 as 12-4-8 to a given volume of water because 24-8-16 as it comes from the package is exactly twice as concentrated as 12-4-8. If you had a controlled release fertilizer (CRF) product (like Osmocote) and were using 14-14-14, you might be directed to use 2 tsp per 8" pot; but if you were using a 7-7-7 CRF product, the directions would call for twice that amount per 8" pot, so plants would actually be receiving the same volume of nutrients.

We can't really cause plants to 'push growth' in winter if they don't want to grow, even by applying toxic levels of N, so making sure plants have appropriate levels of N in winter is no problem. Excess N at any time of the year causes weak, succulent growth and easy access for all sorts of pests, so luxury and toxic levels of N for houseplants is something we would want to avoid, summer or winter.

I use 1/2 tsp of 9-3-6/gallon of water, every time I water, all winter long, even my succulents, and I only have 2 plants of around 100, indoors, that don't look really good. Both are Ficus retusa "Melon Seed" and have been mite magnets since I bought them 2 years ago. This 'at every watering' fertilizing regimen is actually very good for plants, but only possible when using soils that allow the grower to flush the soil as they water w/o having to worry about root problems related to prolonged soggy soil conditions. Other soils that can't be watered correctly have inherent issues that are limiting and related to nutrition, and are mother from which the advice we shouldn't fertilize in the winter were born.

Al

As always Al you put a different perspective on things. I'll have to consider what you've wrote. Thank you.

Thank you too, Mentha.

Al

Al, I have a question about slow release ferts. I love osmocote because I do have so many plants it makes it very easy to take care of them, but I usually go half or even 1/4 strength because I am cheap. I also add things like epsom salts, bone meal, or blood meal depending upon the plant. I really hadn't though that reducing or increasing the amount of slow release used would actually amount to much difference with a slow release because when you wet them each one of the little balls releases a certain amount of fertilizer regardless of how much you use. Can you elaborate on that? So what you are saying if a concentration of NPK is higher it should be diluted more, this would also make one with higher concentrations more economical? What would be a safe concentration to use for once a week feeding and how would you make sure you're not over fertilizing?

Another question do you think the hype of using mycorrhizae is worth the expense? I'm wondering because a potting soil I am looking at has a version treated with mycorrhizae and one without. The one with is a bit more expensive. After watching a lot of videos on the benefits of mycorrhizae I can't help but be excited but there are also some that are independently videoed that say they got no significant difference in the treated and the control plants.

M - I'm going to preface my replies to your questions by reminding readers that I'm basing my comments on the fact that I believe it makes very good sense to adopt the idea that ensuring all the nutrients plants normally assimilate from the soil are A) IN the soil and available for uptake at all times, B) in the soil in a favorable ratio - that is to say in a ratio that mimics the ratio at which the plant actually uses the nutrient, C) at a concentration high enough to ensure no nutritional deficiencies, yet still low enough to ensure the plant's ability to take up water, and the nutrients dissolved in that water won't be impeded (by a high concentration of solubles in the soil solution) is a goal more worthy than anything the grower has little control over.

Mentha commented: I love osmocote because I do have so many plants it makes it very easy to take care of them, but I usually go half or even 1/4 strength because I am cheap. Plants are programmed to take up nutrients most efficiently at a given concentration. Fertilizing at 1/4 strength is fine if you fertilize often enough, but what's important is that the level of nutrients in the soil are maintained at the level that makes it easiest for plants to acquire nutrients. Obviously, this is closely related to watering habits and soil choice. If your soil is one you can water at will w/o worry about what impact prolonged soggy conditions will have on root health/function fertilizing is monkey easy. You pick a complete fertilizer with all essential nutrients and work out what concentration to provide per given interval. Usually, in summer, a full strength dose every 3 weeks is about right. In winter, if one is counting the number of waterings in a 3 week period (let's say 5 for the sake of this example), they can supply a full strength dose every 5th watering - even if that's a 2 month interval. Those using soils that require them to water in sips should be on a plan to regularly flush their soils at intervals (4-6 weeks is good) if they want to avoid fertility (salt) levels too high and badly skewed nutrient ratios, which cause antagonistic deficiencies (as in: too much Calcium can cause a deficiency of Magnesium, too much Phosphorous can cause a deficiency of Iron and several other nutrients).

I also add things like epsom salts, bone meal, or blood meal depending upon the plant. I don't WANT to be critical, but you know I'm straightforward, which is why I'm saying this is going to be fraught with potential problems for most growers on several fronts. First, you pretty much relinquish control over what your plants get and how much they get. Epsom salts (MgSO4) supplies Magnesium and Sulfur, bone meal supplies Phosphorous only in soils with pH below 7.0, and is essentially insoluble in container culture. Blood meal is very high in nitrogen and presents a serious risk of ammonium toxicity (happens when release of ammonium in media occurs faster than it's conversion to nitrate - soggy soils are a BIG contributor to ammonium toxicity) in container culture. This is especially true as soil temperatures drop below 60* F. I think all growers who are focused on their plants rather than the constant analysis of what they're doing would be well-served to simply use a fertilizer like Foliage-Pro 9-3-6 or its equal and be done.

I really hadn't though that reducing or increasing the amount of slow release used would actually amount to much difference with a slow release because when you wet them each one of the little balls releases a certain amount of fertilizer regardless of how much you use. Can you elaborate on that? There are 3 basic ways that Controlled Release Fertilizers release nutrients. Those houseplant growers are likely to encounter, polymer-coated fertilizers (like Osmocote) release by diffusion through a semi-impermeable membrane with the rate of release being altered by composition of the coating and coating thickness. The mechanism of release includes water vapor penetrating the resin coating and dissolving the water-soluble fertilizer core. The dissolved nutrients then diffuse through the coating into the soil. This occurs whether you pour water over the prills of fertilizer or not; witnessed by the fact that a large fraction of nutrients can end up outside of the prills in unsealed bags or containers of product. Soil temperature influences the rate of diffusion, and having the greatest influence on fertilizer release rate, rather than moisture levels.

So what you are saying if a concentration of NPK is higher it should be diluted more, this would also make one with higher concentrations more economical? The directions on the package will guide you to an appropriate solution strength and interval. If you shorten the interval, you reduce the suggested rate commensurately. If you increase the interval, you shouldn't increase the suggested dose any more than slightly or you risk fertilizer burn. The directions are for plants growing well - like in summer. So you need to reduce dosages in winter to compensate for extended intervals between waterings. I find it sooo much easier to use fast soils, water at intervals, and fertilize each time I water. It takes about 5 gallons of water to water my plants every 4 days in winter, and about 1 minute to pour 1/4 tsp of fertilizer in 5 1-gallon milk jugs.

What would be a safe concentration to use for once a week feeding and how would you make sure you're not over fertilizing? It depends on what fertilizer you're using. Following label directions is best, but we need to remember that a plant that will tolerate 2,000 ppm at 70* outdoors in full sun might not tolerate 300 ppm in a dark wintery corner. This will likely bring us in a circle to the "withhold fertilizer in winter" question. The thing to remember isn't that we need to withhold fertilizer because the plant "isn't growing", the plant still needs nutrients to carry on thousands of activities OTHER than growth. So, instead of withholding, we should ensure the nutrients are all there, in as close to the ratio at which the plant uses them (that allows us to keep fertility levels as low as possible w/o deficiencies), and at levels low enough that problems with high EC/TDS (salt) levels can't occur. This is MUCH better than not fertilizing and allowing nature to set its own course.

Another question do you think the hype of using mycorrhizae is worth the expense? I'm wondering because a potting soil I am looking at has a version treated with mycorrhizae and one without. The one with is a bit more expensive. After watching a lot of videos on the benefits of mycorrhizae I can't help but be excited but there are also some that are independently videoed that say they got no significant difference in the treated and the control plants. I have never found mycorrhizal fungi in any of my houseplants, but I find lots of it in the bonsai and potential bonsai I repot in spring and the few I repot in fall (cool temps - it grows very well in the pots I over-winter in the garage w/o me artificially inoculating to add the fungi). This is because containers are generally inhospitable places for mycorrhizae. Some other tidbits: I read recently in Greenhouse Grower Magazine that 78% of the products purported to contain mycorrhizae had no viable populations. Mycorrhizae also make root systems more efficient and thus smaller. If anything occurs that kills or significantly reduces the populations of the fungi in a container, the plant is put under significant stress until the root system can recover. This happens a LOT, due to the inhospitality of containers to mycorrhizae.

REALLY good questions, Mentha. I enjoyed answering.

Al

So if I were to treat my plants with mycorrhizae, I would have to continue with the treatment every so often? I could do that. Do you think that part of the reason the fungus doesn't survive is because many houseplants are grown in plastic? You would think that they would need a little air flow. I wonder if the fungus would come up through the soil if I were to keep my pots on the ground in the summer instead of on shelves like I usually do.

You'll find disagreement on this, but I've found that even if you inoculate with viable strains of the fungi, there is no guarantee it will be the RIGHT fungi OR that it will be able to tolerate the confines of a pot. I've never seen evidence of it in succulents or houseplants, but I find it all the time after woody plantings for bonsai have been subjected to periods of cool weather (but not in summer). I don't even find it in summer (when plants do 90% of their additive and multiplicative growth) in pots kept in full but open shade (full shade with open sky above - like on the north side of a building in the N Hemisphere or north side of a fence so sun doesn't hit the planting directly). If your plants' roots are healthy, there is a sufficient volume of air in the pot to support mycorrhizal colonization of the soil, but there are so many other factors that can deny viability - moisture - too much or too little, pH, soil EC/TDS.

What would you do if you had a plant that relied on a symbiotic relationship with mycorrhizae, but needed treatment for a fungal infection? ;-)

Al

"I recently purchased some Miracle Gro All Plant Liq Fertilizer"

Too vague. I don't know what that is and you shouldn't expect anyone to. I am going to refrain from discussing this until you provide us with the complete analysis, ingredients and instructions.

Thank you for your input Aruzinsky. I have more than enough information from others who have posted to make a decision in regards to fertilization.