Then what explains why the very new growth on some of my plants, especially my calomondin orange tree, would be almost yellow while the temps have flucuated so much, then that very same growth turned green along with new growth as soon as the temps stableized for over a week? Now that the temps have dropped back quite a bit again for the past few days,50's by day and 40's by night, the new growth coming in along with some of the new and old growth on my denias is turning yellow again and fast? These same plants turn green again, once the warmth comes back? Warm nights and warm days on a consistant basis. Is this a fertilzer problem, or the weather to blame? If the drastic changes in weather, from greenhouse to homes, from outdoors to inside are the culprit behind defficiencies, then it is not a cultural problem nor the fertilizer right? Please unconfuse me. It is not a watering issue for sure, since I have them in the gritty mix. Last year when temps were stable in June and it rained everyday, my plants prospered! So, is FP going to be a problem in drastic temp changes? Is it a urea based product? Should it work WELL even with these changes, or will it be locked up in the soil until favorable temps return? Thanks...

Additional pic of a bare spot. Should I be dethatching or aerating first? My soils is fairly compacted and has quite a bit of clay. However, I do Mulch Mow at a very high blade height (to my wife's constant chagrin!)

There's a lot of them, but the most fundamental one that I can remember is the Hoagland's solution. You can search the net for Hoagland's solution and it will give the listing of all the ratios of all essential nutrients. One thing is that some elements like Nickel or Cobalt are required in the ppb range, luckily for most well water, this is a contaminant needed by the plants but doesn't affect humans at that level, but these are present in Hoagland's solution. With that solution you are sure that you did not miss out on any essential nutrient. The Hoagland solution is generic and may not be best suited for citruses, so you will have to adjust the correct ratios of NPK but for sure all the trace elements are present. Some trace elements may not be essential for other plants or are still essential but in undetectable quantities. Some hydroponic nutrients are better than others because they target specific plants, so read the ingredients and ask if it supplies all essential nutrients for targeted plants. I actually did purchase the trace elements only from eBay and mix that with Best formulations for NPK, then used it to grow my bananas in pots using coconut sawdust. The banana is now blooming after two years in a pot. The pot size is 20 gallons, and the banana is 7 ft tall at the trunk. The blooming and fruiting is a sure sign that I have met all the minimum essential nutrient requirements to complete the life cycle of a plant. Bananas were feed essentially only with my formulation and city's water. I still have a lot left of my original 1 lb trace elements, I just perhaps used 2 oz of it to mix with the majors 6-20-20 fertilizer, to make sure banana's required essential nutrients are satisfied. Since I use manure on my potted citruses, I don't worry about adding all the essential nutrients or same formulations for citruses, only at certain times when I don't know why it is still yellowing during the warm season and there are no obvious disease or pest problems.

Ron, if I were going to go with an osmocote type fertilizer (and I may... I just want to consider all my options) I think of the webfoot brand as being far superior... I have used it a lot in the past. Gardengal, thanks! I bought a small box of Dr. Earth a while back to do some comparative trials. They (Molbaks) were out of large bags and the soluble fert. I also wanted to try. Now I'm back in Kitsap Co. again so not sure how easy it will be to find.