Some houseplants have winter as their growing season. So it would depend on which ones you have as to if this is normal for them :) Others have no real set season, and can continue all year. Some have a summer growing season and need a period of dormancy. Which ones are giving you this exciting new growth?

This is a great question, Jerry. I have been growing houseplants for almost 30 years in USDA zone 6, following the advice I got mostly from books by great garden writers from the 1970s and '80s. My understanding was that most plants benefit from a period of dormancy, even those from tropical climates like plumerias, kind of like humans need sleep. In my growing conditions where plants spend six months of the year in my centrally heated house near windows that receive a few hours a day of bright light at best, they do slow their growth considerably. I was taught to stop fertilizing completely and cut back on watering to the bare minimum. This seems to have worked pretty well, in most cases.

But since joining Gardenweb and following Al's posts, I've realized that much of what I learned from the experts was mostly wrong. I've repotted most of my plants into gritty mix and been using Foliage Pro since last May. All but a few of the 50+ plants I grow are doing better than ever before.

So now, as we enter the short, gloomy days of winter, I'm wondering if my plants need to go through dormancy. I did give my amaryllises and clivias 6-8 weeks of temperatures between 40 and 50 F with no water, but I've continued to water everything else with a light fertilizer solution as needed. This includes plumerias, begonias, strelitzia, ficuses, orchids, draecaena, crassulas, kalanchoes, spider plants, bougainvillea, mandevilla and jungle cactus.

I must admit that I'm a little nervous about this when I'm not growing under lights. I'd love to hear what others think.

This is a GREAT question.

For me, fertilizing my plants is determined by how much light, warmth and the kind of mix I provide.
Those that are kept under 12 hours or more light, I fertilize as I would all summer. I give tablespoon a gallon a water of Foliage Pro a week. I too am growing in the gritty mix and 5.1.1 mix which allows me to fertilize copiously all year.

For those tropicals I keep in my home under less than ideal conditions, I feed once a week if that, with a much weaker dose of fertilizer, 1/4 strength a week or less.

For those I keep in my greenhouse, I feed 1/4 strength at every watering.

That is my system and it seems to work well with my plants as they are all thriving.

Some I do put to rest like my Clivia, Desert Roses, and Plumeria, but that is because I don't have the room to keep them in my home or any where else but the dark basement.

well Julianna they all have new growth, I have a few kinds of ficus, croton, aglaonemas, sans, and a couple I'm not sure of, a money tree or something like that. I live in zone 10, and even though the days get shorter and cooler nights, we still get some really warm days through November, over 80, plus my house is very bright.

I'm thinking of cutting the fertilizer back to 1 teaspoon of Foliage Pro per two gallons until spring. I think this is just a flush of growth because of some warm November days, I think. All my outside plants have slowed down, except the tomato's, I'm just going to pull them now, I can't eat anymore.

Not long ago on the Container Gardening and Houseplants forum, there was considerable disagreement about houseplant 'dormancy' that may have seemed wide spread, but that had actually come from primarily two members who argued vehemently and against all reason that since houseplants went dormant in winter that fertilizing was inappropriate. That some of their earlier posts referencing many of their plants enjoying good growth during the winter were pointed to as invalidating the arguments had no effect, other than to illustrate the arguments were ad hominum rather than against the facts. Unfortunately, some of the fallout from the lengthy period of disagreement lingers in the form of those few who might have believed that houseplants do go dormant.

Some houseplants are genetically predisposed to slowing down or 'resting' during the winter months. Those neutral or short day plants that are not so affected can still be slowed by diminished photo-intensity, decreasing photo-period, and low temperatures, and those cultural conditions can also contribute to a genetic predisposition. The bottom line is: Houseplants slow growth based on genetic and cultural influences, both of which vary considerably - but they don't go dormant ..... to which all posters to this thread thus far will attest.

I think it's easier to say you shouldn't fertilize in the winter when your vision is narrowed by your individual choices, or if you make assumptions. Make the assumption that all are growing in a water retentive soil that requires you to water in sips to prevent root rot, and you're much closer to being accurate in suggesting others following suit refrain from fertilizing in winter.

Watering in sips ensures that solubles (salts) from tap water and fertilizer solutions accumulates in the soil, so of course contributing to this accumulation is a bad thing. By the same reasoning, and because a major source of salt accumulation is tap water, we should also stop watering. It's not the act of fertilizing in winter that causes problems; it's soil choice/watering habits, and to a significant degree - fertilizer choice.

The goal of container gardeners, when it comes to fertilizing, is easily defined. Our plants grow best if we maintain all the essential nutrients in the soil at all times, in the same ratio as that used by plants, and at a level just high enough to prevent any deficiencies.

Since plants don't stop growing in winter, they need all the essential nutrients in the soil to grow normally and to keep their systems orderly. It is extremely difficult to manage this when you can't water properly, because you can't manage the o/a level of salts w/o risking root rot. This is one of the more serious disadvantages of using heavy soils.

Look now to the grower who uses a fast soil that allows him to water copiously w/o worry about root issues. This grower is free to fertilize every time he waters if he wishes to do so; this, because he can continually flush the accumulating salts from the soil every time he waters, and replace them with a low dose of fresh nutrients in a favorable ratio. This allows the grower to maintain the lowest fertility level possible w/o nutritional deficiencies. It doesn't get any better than that, and it is the best way to ensure the most attractive foliage, within the limiting effects of other cultural influences.

A brief word about NPK %s. Choosing a fertilizer with an inappropriate NPK % because it says "Houseplants" on the label is a fast & sure way to end up with badly skewed nutrient ratios in the soil. I'll use the popular Schultz 10-15-10 houseplant fertilizer as an example.

This fertilizer supplies almost 5X as much P as plants can use in relation to N. This ensures an excess of P in the soil (solution) that by Liebig's Law of the Minimum is harmful; and it would be particularly harmful in situations where the grower is required to water in sips. In fact, the accumulation of P to 10-20-30-40 times the amount required for a healthy plant that results from watering in sips, is probably more harmful than the potential deficiencies caused by withholding fertilizers in winter. Is it a wonder some think it inappropriate to fertilize in winter?

Choosing a less than ideal NPK formulation is much less a problem when using a fast soil and watering correctly, because that combination prevents the accumulation of 1 or more nutrients; but it's still better to use an NPK ratio that most closely mimics that used by the plant.

Bottom line: low levels of a full compliment of the nutrients plants assimilate from soils in the same ratio as that used by the plant are not only acceptable, but desirable.

Personally, I fertilize all winter long, every time I water. I use the gritty mix, water until the water flows freely out the drain hole, and use 1/4 tsp of slightly diluted (from full strength) FP 9-3-6. I don't plan on changing soon because my plants have looked better than ever since I fell into this regimen. I even fertilize my succulents this way with no sign of rebellion or wayward habits.

I hope this effort makes it to the thread - I somehow lost my first two attempts at a reply as I was approaching the end. Grrr! ;-)

Al

It made it, Al, and thank goodness!
Nice post.

Josh

Thank you so much Al, sounds very logical and sound, and much appreciated.

So what I'm taking from this is that all my houseplants are in a gritty mix, are getting a nice flushing every week with FP 9-3-6, 1 tsp per gallon, the plants have never looked better, are still growing and enjoying life, why rock the boat?

About every 5th week I do flush with just plain water and wash off the leaves, not sure why, I just do.

Thanks to everyone that posts, I always learn a thing or two, and it's nice to hear other peoples idea's, there is always something to take away even though many of you are in different climates than me. In fact, the more I hear about all the hassles you all go through taking your plants in and out of the house during the different seasons it makes me appreciate living where I do.

Jerry

How WARM is it inside your house? That plays a part as well.

I just fertigated some of my plants this morning, so I thought I'd revisit this topic, as well.
I've cut the dose to just a little under 1/4 teaspoon Foliage Pro per liter of water. The plants
that I fertilized today are Citrus, a Dragon Fruit seedling, Avocado, Hoya, and Christmas Cacti.

Josh

Tommyr, my house rarely gets below 65, and that's only when I have all the sliders open and it's getting late in the day. My plants enjoy nice weather all year long, I'm sure that helps.

My outside containers have slowed their growth so I have cut down on the amount of fertilizer that I use, but I'm still using some since they are all in a gritty mix.

Jerry