First, you're correct in thinking that half as much 20-20-20 will yield a solution the same as 10-10-10 (if it was soluble). Another way of saying it is, 1 tsp of 20-20-20 in a gallon of water yields a solution of the same strength as 2 tsp of 10-10-10 in a gallon of water. Generally though, 10-10-10 formulations are slow release, which is different from controlled release, and 20-20-20 formulas are usually soluble in water. While you wouldn't normally mix 10-10-10 in water, it does contain half the N, P, and K that 20-20-20 contains. A lot of growers are quick to recommend a fertilizer with a specific NPK %, but most are unable to tell you precisely why they recommend it. Often, they will offer the idea that fertilizers with a higher first number (nitrogen) are too high in nitrogen to be suitable for houseplants; but they overlook the fact that the amount of nitrogen supplied has nothing to do with the fertilizer ratio, and everything to do with how much N is supplied by the grower. It's as easy to oversupply nitrogen with 10-10-10 as it is with 24-8-16. Actually though, the consequences of oversupplying nitrogen when using 1:1:1 ratio fertilizers like 10-10-10 or 20-20-20 are considerably more severe because you can't even supply an ADEQUATE measure of nitrogen (using 1:1:1 ratios) with out oversupplying both phosphorous and potassium. The perfect fertilizer program would find the grower providing all the nutrients essential to normal growth in the exact ratio at which the plant uses the nutrients, and at a concentration neither so dilute that deficiencies are limiting nor so concentrated that toxicity or antagonistic deficiencies are limiting. It's actually impossible to come even close to achieving that end when using a 1:1:1 ratio fertilizer, or fertilizers actually providing more than 1/6 as much P as N. After the factoring is done for the fact that P and K are actually reported as P2O5 and K2O in a fertilizers NPK %s, you'll find that fertilizers with 3:1:2 ratios (24-8-16, 12-4-8, 9-3-6 are examples of 3:1:2 ratio fertilizers) supply nutrients in almost exactly the same ratio as the average at which plants use therm. There is a significant variance in the overall volume of nutrients taken up by plants, but only a small variance in the ratio the plants actually use. I grow hundreds of species of plants, indoors and outdoors. I formerly used Miracle-Gro 24-8-16 or 12-4-8, to which I added other nutrients. I now use Foliage-Pro 9-3-6 for every plant I grow. It contains all the essential nutrients in a very favorable ratio. It also gets none of its N from urea, which helps to minimize the impact of low light and helps keep houseplants compact. I know that all sounds complicated to a beginner, but if you have questions, don't be afraid to voice them. Al This post was edited by tapla on Tue, Sep 24, 13 at 9:08

Every single fertilizer should have three numbers indicating the amount of 1. Nitrogen (for leaves) 2. Phosphorus (for blooms) 3. Pottash (for blooms and basic health) A plant needs all three of these to be healthy. What I do is change fertilizers about every two months. I always us 1/4 teaspoon fertilizer to a gallon warm water. Most of the time plants do very well with a balanced fertilizer. Balanced means all three numbers are nearly the same. So any brand 20-20-20 or 14-14-14 or similar is a good basic fertilizer and you can't go wrong with a balanced fertilizer. Something like 3-3-3 is balanced but is not actually giving you much fertilizer. During the summer my plants get Peters 20-20-20 (any brand with the same numbers is similar). Some have urea which locks up the plant so it can't take on fertilizer water.) Then after two months when I want more bloom I go for Peters 12-36-15 which should give me more blooms. Then before a show I go to 5-50-10 for a humungous amount of bloom. BUT NEVER use a fertilizer like 5-50-10 for a long time because the 5 means leaves are not being fed much and the last number 10 means the health might suffer just a bit. I use this high number for only 2 weeks before a big show. Other fertilizers which often don't show numbers are good as well. This includes Fish emulsion which is a natural fertilizer (sometimes smelly for a few hours). Bone meal doesn't have a number but it is a natural fertilizer taken from hooves of animals such as cows and horses. Some growers use natural fertilizer such as goat manure that has been processed. Be careful that natural manure is well dried since it can burn plants. Nancy

Well, I'll chime in with a straight face, MOL..... my 'maters are all in pots, and need water at least twice a day, I mix up some MG in a bucket and pour some into each bucket I have next to each plant, I keep that water-bucket there so all I have to do is dip out some water and not drag the hose all over the yard.. so essentially I am giving each 'mater some liquid fertilizer each time I water...I won't even speculate at what strength but the water is blue, from the MG... most of my 'maters are getting pretty big, they are from last year's planting Tom brought me.... but they are still setting fruit so I keep them going even tho' they are pot-bound now.....I speculate that the only thing that keeps them going is the liquid fert., by now, because any other nutrient in the potting-mix has been long-gone..... works for me.... sally

Yes, that is what "they" say...mid July to early August. Waiting later may result in no ripened fruit as ripening slows down when the sunlight per day decreases and the temperatures drop. I'm going to try fall for the first time this year and plan to use sun shade cloth b/c I think it will be necessary in the scorching August sun. Good luck.