Once per month is likely not frequent enough if you're growing in a good container soil.

An ideal fertilizer program for nutrient-loving plants (some prefer a very spare soil) would see nutrients readily available for uptake in an adequate to luxury consumption range (real terms) at all times. Too low a level of nutrients creates a deficiency range & will effect growth, while over-nutrification creates toxicity and poisons the plant or creates antagonistic nutrient relationships where an abundance of one nutrient makes it difficult or impossible for the plant to assimilate another nutrient.

Plants take up nutrients with the water they absorb from soil. Modern chemical fertilizers are designed so that they are most easily absorbed at a certain level of electrical conductivity in soils. The recommended solution strength on the fertilizer package provides a conductivity level that puts nutrients at or near near their maximum availability for plant uptake. When you fertilize frequently with minimal dosages, you never reach optimum conductivity unless fertilizer and metal salts are accumulating in the soil. This is an unwanted situation & is exacerbated by poor watering habits or a soil that exhibits inadequate drainage.

I pay pretty close attention to what's going on in my containers. I grow in a free-draining mix & irrigate so that a fair amount of water exits the drain hole at every watering. I most often see signs of oldest leaves becoming a lighter green at the 3-4 week mark, so I fertilize with a full strength solution every 2 - 3 weeks. I fertilize more frequently when plants are growing strongly and temperatures are warm (requiring more frequent water which leaches nutrients), and less frequently when temperatures are cooler and growth is slowed. The only exception would be if soil temperatures get quite high during the hottest part of summer & plants go semi-dormant. I usually withhold fertilizer applications then until growth resumes.

Al

Great info! Which product do you suggest using? Someone suggested Miracle Grow liquid fertilizer, but I'm not sure exactly which product to use...they have liquid and powder based stuff (that I'm assuming you would mix with water or maybe just sprinkle on and then water over).

I use Miracle Grow SuperBloom every time I water

Bonnie - on everything you grow in containers? What about your foliage plants? Container soils usually have adequate levels of Phosphorous available.

Viche - Depending on plant material, I use various soluble fertilizers (like MG) in combination with various CRFs (like Osmocote), and fish/seaweed emulsions. I add Micromax (insoluble) micro-nutrient granules when I initially make the soil & supplement it later as required with the addition of STEM (a soluble source of micro-nutrients - mixed into fertilizer solution).

Al

Ok, that sounds like a ton of stuff. Isn't there some easy way that I can achieve 90% of your plants health with 50% of the effort? For example, Can I use Miracle Grow or some other brand potting soil to get the STEMs or Micromax, add some osmocote at the beginning of the growing season, and then just add liquid miracle grow every 2-3 weeks? Seems like nutrient overkill to me.

You can look at fertilizers intended for hydroponnics, Viche. DynaGrow makes a popular line.

The problem with most fertilizers is that they don't contain all the essential nutrients and those that do often contain nutrients that aren't soluble in water and won't become soluble in a container in time for the plant's needs.

Calcium is a nutrient most plants need almost as much as they need the big three (NPK), but there isn't a Miracle Grow fert on the market (that I know of) that has any calcium.

One could go to single source nutrient products and combine them to provide all the nutrients such as adding lime (calcium and in some forms magnesium) to containers. That complicates things and often these sources won't release nutrients in soluble form fast enough or at the right time for container plants.

That's why geeks like Al (compliment, not insult) develop methods that seem complicated in an effort to grow plants optimally.

If you want a method that offers much of the benefit with less effort then pick up some DynaGrow for plants that you grow for foliage and Dynabloom for those you grow for fruit/flowers. All nutrients are in forms readily available to plants and there are no essential nutrients left out or present in a proportion that adversely affects the availability of other nutrients.

The Dynagrow line can be found online or at any hydroponics store.

Great!! I'll look into it.
Would using osmocote or miracle grow potting soil along with Dynagrow products be overkill?
Does anyone use there stuff for outdoor plants in the ground?

Would using osmocote or miracle grow potting soil along with Dynagrow products be overkill?

If you are growing canna or any other heavy feeder, no. If you are growing a Mediterranean herb or some other plant that does best in really lean soils, yes.

Does anyone use there stuff for outdoor plants in the ground?

Probably, but nobody I know of. The various brand names really are not important. What is important is how much of each nutrient is present and how long it takes in a particular environment to become usable by plants.

Hydroponic fertilizers are always fast acting and require no processing by weather or soil critters to become available to plants. They are usually complete fertilizers containing all essential nutrients unlike many ferts intended for containers or soils where certain nutrients are left out for reasons I do not understand. Given how important calcium is for most plants why doesn't Miracle Grow include any? No idea.

Thanks for the advice. Bought some Dyna-gro Grow and Bloom formulas today. The hydroponics guy at the store said to use it at a maintenance level every watering. Seems like a bit overkill to me. I'll have to read the directions myself. I guess I shouldn't be using the Miracle Grow potting soil with this stuff?

Yep the instructions say: Indoor Plants 1/4 to 1/2 tsp per gallon of water with every watering

Outdoor plants 1/2 tsp per gallon of water with every watering. For monthly feeding, use 1 tsp per gallon of water.

Guess it really can be used every watering. I'm not sure that I want my indoor plants to grow out of their pots though. I just want them to be healthier.

I'm not sure why you wouldn't use MG potting soil because you've chosen a particular brand of fertilizer. I can think of other reasons you could make a better soil choice, but they don't hinge on fertilizer choice.

You seem rather anxious to add fertilizer, so let me caution you that you can easily find yourself in a situation where the salts in your fertilizer(s) are so concentrated in soil that they make it impossible for plants to take up water and nutrients (nutrients are dissolved in the water plants absorb). Some soils make it difficult to prevent this because you need to water them in sips to curb the possibility of root rot.

Just a word of caution: because a little fertilizer added proves to be good, more may not be better and could cause severe damage very quickly that cannot be reversed.

Al

MG potting soil contains slow release fertilizers....just thought it might be overkill. Is there another easy (ready-made that I don't need to contruct from 4 to 6 components) soil that is better-draining?