Did you use excessive amounts of N? Last fertilized? With what/what strength solution?

How long since last repot?

When you water, are you watering so at least 10-15% of the total volume of water applied exits through the drain hole?

Was the chill very sudden? What was the temperature range prior to the chill?

Al

Almost certainly you have a build up of salts in your container soil. This might be a good time to repot, otherwise you should leach out the salts by putting the whole container in a bath of water, letting water run into the tub and over the side slowly for an hour or so. Then put the pot in a raised position to let it drain thoroughly. Al

Tapla, Calistoga;

N: Couple table spoons of miracle gro, 2 times. A couple of weeks ago.

Never been repotted.

In winter never add enough water to drain out bottom. In summer they sit outside and get washed through by rain water plus added hand-watering.

Does sound like too much N / salt build up from your kind responses.

Well, there are several reasons that individually or in combination could cause the symptoms you described. I also suspected a build-up of soluble salts as a strong possibility, but wanted to hear your answers before I made conjecture.

I wish you had included where you live in your user info. It's very valuable info to those seeking to offer their most specific advice.

Ok - we already suspect it's a salt build-up from fertilizer and irrigation water. This link will help you understand Watering Technique and its affect.

The plant is so root bound that it's likely water is penetrating the root mass unevenly, or almost not at all. If it's been several years, a repot is in order - and a repot is much preferred to simply potting up. Being root bound has considerable effect on branch extension and o/a growth, too. Read here about Repotting and Tree Care.

The symptoms you describe are also consistent with ammonium toxicity, and it sounds like conditions (high fertility - urea based fertilizer - cool temperatures) are favorable. If you are using Miracle-Gro, you are using a fertilizer that supplies it's N in urea or ammoniacal form. Urea is either converted to nitrate-N in the soil by bacteria, or it is taken up directly by the plant. The plant can store large amounts of N in nitrate forms, but cannot store much N in a the ammonium form w/o symptoms of ammonium toxicity - especially when cool soil temps or soggy conditions inhibit the bacteria that convert the urea to nitrate form. In short, it's best to withhold urea-based fertilizers if there is a chance soil temps will be below 55*.

Now factor over/under-watering into the equation & you have plenty to ruminate on for a while. Remember - it needs to be repotted. ;o)

Take care.

Al

Citrus grown in a container if properly watered, that is enough water is applied that it is seen to run freely out of the drain holes, will seldom be over fertilized. If you observe how the foliage responds, the newest growth, the shade of green of the leaves,darker is better. The size of the new leaves, normal is better. Too much nitrogen will cause leaves up to twice the size of 'normal'. Most people will buy their citrus in three gallon size plants and pot into about 18 inch pots, hopefully with soil mixes as discussed on this forum. For at least the first two years an application of about a tablespoon citrus labeled fertilizer monthly, year around works well. Nightime temperatures into the low forties should be no problem. This is the advice offered by citrus wholesalers here in California. Al

Actually, the type of nitrogen applied can have nearly as significant an effect as the dose. N supplied as urea and ammoniacal-N can almost always be counted on to produce more stem elongation accompanied by lengthened internodes, along with greater leaf expansion (size). Nitrate-N, on the other hand, is the friend of bonsai practitioners and other container growers who would like to see their plants producing compact growth.

A couple of comments about the fertilizer advice by the citrus wholesalers, as reported by Al (Calistoga): I still think it needs to be tempered. While air temperatures may not present much in the way of problems for most citrus when they sink into to the low 40s, soil temperatures that low surely can/will. If soil levels of N are at adequate to luxury levels and supplied as urea or in ammoniacal forms, it's a good bet that some degree of ammonium toxicity will occur, and it can/will be exacerbated in containers with soils heavy with water/low in aeration. All commercial operations are aware of this & either withhold urea/ammoniacal-N when soil temps are below 55* or supply at least 60% of N supplied as nitrate.

Al

I have been told by gardeners east of the rockies that they are unable to find fertilizers formulated for citrus with all the minors included and plainly labeled "Citrus". Perhaps this helps account for the variation in results. Container grown citrus is a huge market here in northern California where only the very minimal winter protection is required. Al