3 year old dwarf kishu mandarin tree

As I stated in the subject ID, I was given a dwarf mandarin about 2 seasons ago (it's indoor/outdoor). It looks totally fabulous right now-very green and bushy (probably because it been out on the deck all summer), unfortunately it has NEVER had any flowers. I know that they don't fruit for like 3-5 years, but it was already a year old when I got it. During the spring and summer (up until October) I use a 16-16-16 fertilizer when I water it. What the heck am I doing wrong? Oh, by the way did I say I'm near Boston, MA--Any healthy citrus here is a minor miracle.

I believe that with citrus there is a heat requirement for flowering. Like bananas, I think they need something along the lines of 18 months at temps over 40 degrees F to flower and produce fruit. I wouldn't be surprised if I were wrong about that, but I do know cold damage sets in at 40F and once root loss sets in, it is not a happy thing.

The other probable cause for trouble on most citrus is the watering requirements. They don't like to get too much water nor too little. It really helps to know just how fast the soil in the pot drains and how regular it's watering needs are. Some varieties are notoriously fickle about that, like my Meyer lemon. I learned the hard way just how touchy that one is.

There are commercial fertilizer programs out there for citrus. I have not used any specific program. I feed mine some liquid compost a few times a year because they are in pots and don't naturally get the nutrients they would if they were in the ground.

If you've been really good about keeping it warm and suitably watered, the only other potential issue is light. They like a lot of direct sunlight, in excess of 6 hours really when they can get it. I can't think of any good reason for it not to be blooming and producing for you.

It could be that you didn't get a kishu at all, but a non-fruiting variety. If you have thorns you are looking at the rootstock, mandarins generally don't have thorns, but are grafted onto a rootstock that does. I've seen some citrus at the big box stores were that exact problem has been really bad long before the customers ever got the plant.

I hope this helps.

Is it true that if a citrus tree freezes, the shoots will have thorns, & will not fruit.

behill-That's interesting do you know why?

Yes it is true that citrus that freezes to the root will grow back full of thorns and with terrible fruit when you get fruit at all.

The reason is that most fruit, regardless of type, is a grafted tree. The rootstock is from one tree and the scion is the variety of fruit you get. Citrus is usually cultivated this way as well for consistency of the final fruit instead of the craps shoot you get when growing from seed.

The standard rootstocks for citrus are generally very thorny. When we get a really hard freeze it can kill off the top bits that are called the scion leaving only the roots behind.

I never doupted that it was true :) just didn't know why. That makes sense tho.Thanks

You're welcome! Fruit trees are my idea of fun so those kinds of questions I'm lucky enough to know the answer off the top of my head.

I'm watching the temps fall in my greenhouse and trying to figure out what to use as a heater. It amazes me that Laurie has a good citrus tree of any type even with the indoor/outdoor wheeling. The fact Laurie is in Boston makes it even more likely she's seeing the rootstock grown up into a proper tree since the roots are often much hardier than the scion.