Being an indoor grower myself I share the same challenge as you in keeping these trees manageable. You don't really have much choice but to prune since it's undesirable to have such a tall tree inside. Aside from scraping the ceiling and making the tree difficult to move around for maintenance, the foliage near the top would be less than optimal in photosynthesizing the little light available at that level. I think the new growth is the tree's reaction to this situation. I would prune it back to a point just above the new growth for now. Since it appears to still have a considerable height I would consider topping it at a future date to force it to branch at a lower level. However I would not do it until the tree has had a chance to recover. Hopefully Jim can offer us some tips on how to make these trees bushier over the long term. Take the tip from the pruned section and root it as a cutting thereby continuing its node count. Repeat and one day you will have a mature, fruiting grapefruit tree. I think it would be interesting and you have nothing to lose. Regarding taking the tree outside, you have to weigh the benefit against the possibility of exposure to pests and having to deal with them before returning the tree indoors.
One of the main ingredients, produced by the plant itself, that enables the plant (or in this case a citrus tree) to grow, is Gibberillins . The function of gibberellins, is to elongate the internodes. The more gibberillins produced, to a point, the longer the internodes, thus the taller the plant. This type of growth pattern is commonly accomplished artificially by spraying Gibberellic acid (GA3). Growth regulators work by reducing the effectiveness of gibberillins, thus reducing the growth. Growth regulators are commonly used on many fruit and vegetable crops (Alar on apples for example). I believe the particular growth retardant that was used in citrus research, that I posted, would not be a problem. I have read some of the research, but have never bothered to to check on it registrations. However, it would be a simple matter to look on the Internet and read the information. - Millet (1,441-)
The beanstalks that I described upthread look like the ones seen at the top of the lemon tree in the thread Lemon Tree Concerns | UBC Botanical Garden Forums. This reinforces my hunch that it's actually normal for these trees to grow like this. If that's the case, some varieties are just not well suited for growing indoors.
JK, I would not call the pictured trees beanstalks. They certainlly are not what I think of as "beanstocks". - Millet (1,437-)
Interesting. It's true then: A picture is worth a thousand words. I thought beanstalk would be an appropriate description of a single, straight, leafy stem without any side branches. So what did you envision when you read my description using that term?
thanks again for the informative replies, i've yet to make a move on this and havent really done much with the tree, except for keep a close eye on it, the three new roots are really going strong at the moment, so i think i may just leave it be for the time being..
Below are some links that in part relate to this and other threads regarding seedling Grapefruit and pruning of Citrus. I mentioned shearing for container plants in another thread. Below is a look at hedging and topping for outdoor in ground, row planted trees. Texas Citrus - Pruning Citrus A link to an article in regards to Spring pruning of outdoor in ground trees. Spring not necessarily best time to prune citrus Four links with overviews of container Citrus care. Growing Citrus in Containers Growing Citrus in Patio Containers Home Fruit Production - Citrus The Victory Garden . Grow . Primers & Projects . Indoor Citrus | PBS What many of you want to know is how to prune indoor containerized Citrus. A lot depends on the type of Citrus and the subsequent variety of that Citrus type. Pruning a dwarf Rio Red Grapefruit may only require a light trimming every now and then to achieve fullness but a semi-dwarf Marsh Grapefruit may need a heavier pruning to force lateral shoots. Some Grapefruit grow bushier at younger ages than other known clonal types. Knowing the growth habit of the variety of Grapefruit you want to grow seedlings from will help you a great deal for when you want to grow these trees as containerized in the home trees. The problem that many of you have had is that you want to take seed from a store bought fruit and grow it like it was a dwarf tree. I suggest that if you want to grow semi-dwarf to dwarf form seedling Grapefruit indoors in the home that you get fruit from a dwarf form tree instead of store purchased fruit that in most but not all cases came from standard, not budded or grafted onto a dwarfing rootstock, trees. Jim
Thanks for the links, Jim. I think part of my problem stems from growing trees on their own roots, without dwarfing rootstocks.