I am growing Gold Nugget (year two) and it has fruit but I won't know about it until much later as it is quite late. One other advantage of Gold Nugget is that it hangs well on the tree, giving it a chance to sweeten even in cooler climates (I live in a fog pocket just south of Morro Bay, a few blocks from the back bay).

I also have a 2-year old Kishu, having fallen in love with it while still condemned to live in Southern California. It has quite a few fruit on it this year, but while colored up they don't look "ready". The skins seem way too tight. I remember them as very loose. So I'm not sure.

All my citrus are in an "L" formed by south and east facing sides of my house, right up against the house. It gets uncomfortably hot there (when the sun shines) and is the only true "hot spot" I have. They are protected from wind but loose the sun at about 3 pm.

As for Trovita, I've been told it is overrated. Someone in a cooler climate swears by Cara Cara, again because of its ability to hang long on the tree--well into the summer. This gives more time for sugar formation.

Some people also swear by Epsom salts to sweeten up citrus, both foliar and on rhe ground.

Thanks for the heads-up on your kishu, Steve. I have also noticed "tight" skins on my Clementines that just never seems to ripen up. Your climate is cooler than mine, though - Los Osos is a cool place in many ways :-)

My Owari Satsumas on the other hand develop the nice loose skins and good flavor.

I'm thinking of going ahead with the Gold Nugget and holding off on the kishu for now - hopefully somebody else will chime in.

I'm continually amazed at the wealth of information one can dig up about citrus on the net - except, it seems, good information on summer heat requirements for ripening. All I've found are a couple of words that may be anecdotal and copied from one source to the next.

I live in the cooler edge of the wine country - pinot noir and chardonnay grapes are grown - so there is some heat, but not enough for many sweet citrus. Friends in the warmer parts of the Bay Area like San Jose are able to reliably sweeten up most citruses (most grapefruits excluded) that I cannot.

John

I would say Kishu, Gold Nugget, Cara Cara and Oro Blanco grapefruit. Though I live in the warmer area of the Bay, I have a cold micro climate due to neighbors growing towering oaks and pines.
I recommend that you go to a "citrus tasting event" held by Four Winds in most local high end nurseries - usually in Feb/March. You can talk to the Dillon family members who founded Four Winds. They will give you more information on citrus that grow well in your neighborhood than you will ever need! And provide yummy locally grown citrus to taste.
One word of caution - please do not harvest your citrus when the others in the warmer areas of the state do. In my yard, I let my citrus hang a few weeks longer on the plant and they ripen/sweeten much better. This is because of the cold microclimate in my back yard. As steve says, someone on another forum has had very good luck with Cara Cara in Santa Cruz (I am growing my own but the fruit is still not ready).

I would echo some of the information presented already. In my opinion, the citrus that fully ripen in cooler climates, such as Northern California, are those that hold on the tree well. For instance, there was a recent posting on the cloudforest site from the person ashleysf mentioned about Cara Cara Navels hanging on the tree 9 months AFTER ripening and just getting better over that time.

Many mandarins do not hold on the tree very well. My father-in-law has a 20 year old Owari Satsuma that always stays tart and doesn't ever develop the richness or sweetness that I appreciate in mandarins. Owari does not hold all that well on the tree. Gold nugget, on the other hand, ripens in the spring and will hold on the tree all summer.

There does not seem to be all that much information on this quality of different citrus varieties on the internet. I guess we will just have to experiment. I recently bought a page mandarin in hopes that it will produce good fruit here. I will let you know in a few years.

-Brett

I would ditto ashleysf on Oro Blanco. When I grew them in So. Cal. they could hang on the tree for months with very little deterioration. Before I moved permanently to the Central Coast and played part-time tag with my current home, I had a containerized Oro Blanco here that put out a few good fruit before its lack of care in my frequent absence killed it. I now have a second tree, in my "hot zone", but it's just new, so no reports yet. I do, however, have high hopes for it.

I'm hoping to someday show that Los Osos can be more than the land of (very sour) lemons (and *lots* of sand....and fog....).