I'd say use Foliage Pro at full strength, since you'll be flushing when you water.

I'm in California, and my terracotta pots are drying out quickly and staying very hot, so I have no experience with cool soils. My plants are well-established and I'm watering every 2 - 4 days or so, but if they were newly potted, I might water every other day....not a full drenching, but enough to keep the mix more evenly moist while the roots are still acclimating.

Osmocote should be active above 65F, I imagine. Others might know more.

Josh

Josh, good info)

Jrl, 55 degrees is not going to slow your growth or cause issues that you described..Temps below the 50 threshold almost always will with most any sub-tropical or tropical plant in pots..

Your problem was most likely caused from excessive dry soil at the root zone which occupies mostly the top 2/3rds of a repot into the gritty mix..The bottom usually of the mix, stays moist while the top can dry out faster until the roots occupy the space throughout..

Josh made a very important point that most gritty mix users tend to forget and what is sad about all this, is that you can practically water every day and not worry about root rot..I too have killed many plants the past making the same mistake that Josh tries to help us avoid..

MIke

This post was edited by meyermike_1micha on Sat, Jul 5, 14 at 12:54

Thanks guys, I'm still convinced it was the temperature of my soils. I have learned to much from this site to do something as simple as under watering. If this was the month of December and my plant was in a sunny but cool sunroom the first thing people would suspect would be WLD. Thank you with all your help and have a happy weekend.

Citrus root growth is greatly affected by environmental factors, particularly soil temperature and moisture. Three distinct cycles of root growth have been observed in mature trees growing in Arizona, California, and Florida. The first root flush in Florida usually occurs between late February and early April, the timing of which is regulated by prevailing environmental conditions. The timing of the two remaining flushes are inconsistent, varying considerably between years and trees. However, distinct bursts of root growth frequently occur during the periods of May-June and again during August through October. It should be recognized that during the warm months, active periods of root growth can occur at any time in a series of smaller, reduced flushes or as major peaks of root growth activity. There is also some indication of biennial patterns of root growth in Florida citrus. The magnitude of root growth during one year may inversely influence root growth during the following year.

In general, root growth is periodic during the months of February to early December with periods of inactivity occurring only during periods of shoot flush. During spring, summer, and fall, alternation of root and shoot growth has been repeatedly observed. For example, root growth activity declines with the initiation of each new shoot growth flush and then increases immediately after the cessation of shoot elongation . This alternation of growth is thought to occur as a result of competition between roots and shoots for photosynthetic carbohydrates.

In addition to carbohydrates availability, temperature and soil water content appear to be other important factors governing citrus root growth. The minimum temperature at which citrus roots will grow is approximately 54 F while in controlled experiments, maximum citrus root growth occurs between 78 and 90 F. In Florida studies conducted in buried observation chambers, root growth increased as the mean monthly soil temperature increased during spring and summer and decreased as soil temperatures declined during the fall and winter. The most active period of root growth occurred during the summer when soil temperature was above 80 F. Seasonal differences in soil temperatures within and between years can greatly affect the timing and magnitude of root growth processes.

Much of the new growth which occurs during the year serves to expand the citrus root system and to replace roots which have died or are no longer functional. Shedding of fibrous roots may occur at all times of the year, but highest turnover apparently occurs during the winter months and is probably related to lack of available carbohydrates