Aside from coppicing, there are two additional means of reducing the size of this tree: First-and this applies to any broadleaved species-heading back cuts-always to a lateral-to each and every branch in the crown, a very old technique known as drop-crotch pruning. There, now that everybody is done laughing at the funny name, that's a real thing. Via this method, one could arguably hold any such tree to a given size almost indefinitely. Do I think this a good course of action? No, of course not! The other method is via growth regulators, either sprayed, soil-drenched, or injected into the tree. The chemical paclobutryzol is one such growth regulator. This is not something you pick up at the hardware store-strictly restricted use. I don't expect that method to be employed here either! +oM

Loolie, I wonder if you were ever able to learn more about the root system of your eucalyptus citriodora. I also have a citriodora that's about the same size as yours and am trying to find out how deep the roots might go (in terms of watering, in my case). We're in an extended drought in California, the opposite of your weather when you wrote your message more than 5 years ago. And our soils are likely to be very different, which affects root structure, from what I've read, so even though our trees are the same there could be big differences in their root structure. Nevertheless, I'd be very interested to know what you eventually found out and what happened with your tree. By the way, I didn't find your question metaphysical, per one of the replies, nor unreasonable as others seemed to imply. So, again, if by any chance you ever run across this message, I'd love to hear your update.

Funny, because that Don guy re clarified his question almost to the exact same way I was going to. Yes depth is probably not the right question. So I'll clarify, which SPECIES do not have fibrous root systems. The link to the post above rattles off but a few that do have fibrous roots systems. Is it possible to rank these plants as having few, moderate or extreme fibrous roots? Feel free to add more genus or species. I apologize for the mix of common and botanical names. I put in my ranking based on my experience. Baldcypress - Moderate River Birch - Extreme Butternut Catalpa Malus - Moderate Cornus kousa - Few to moderate American Hornbeam -Few to moderate Horsechestnut - Few Buckeye - Few Ironwood - Few American Linden - Few Amur Maackia - Few Pin Oak Northern Pin Oak White Oak Red Oak Swamp Oak Eastern Redbud Dawn Redwood - Moderate Sassafras Serviceberry Sweetgum Sycamore Tuliptree - Moderate Tupelo Yellowwood - Few to moderate Sugar Maple - Few to moderate Silver Maple - Extreme Red Maple Boxelder - Few to moderate Cottonwood - Few to moderate Kentucky Coffee Tree - Few Turkish Hazelnut Norway Maple - Extreme Shatung Maple - Moderate Paperbark Maple - Moderate Japanese Maple - Moderate (sensative to disturbance) Witchhazel - Few to Moderate American Beech - Extreme European Beech Amur Chokecherry Pagoda Dogwood - Few Fringe Tree - Few Hawthorn - Few This post was edited by whaas on Wed, Jul 3, 13 at 22:04

thanks for the response I had an E.gunnii for two yrs or so but after a heavy frost it died back to earth.Here in northern Greece in the last 5-6 yrs it gets really chilly in the winter. for example 2001 December -19 C. 2003 winter -17 C 2006 February -20 C Also snow is prevalent here every winter.When it comes to the icy seberian winds...no comment.But I still try planting here subtropical species I hope the 3 species I sowed are more promising. thanks again any other experiences?