They do require some supplemental summer irrigation here. While we may be known for our damp climate, it is really very dry here in summer. The weeping katsura in my old garden wilted frequently during drier periods if I was not on top of the watering, as did my 'Heronswood Globe'. The ones that do the best here are in irrigated gardens or large enough and well-established enough to withstand prolonged dry spells.

And it doesn't even get very hot here in summer!

Around here, Katsura planted on sites with limited infiltration or restricted root zones do not do well through the summer. In open areas or large lawns, they are fine once they have established for 1-2 years.

I've got 2 2nd year C. japonicum seedlings in my "nursery" (pot ghetto for young plants), started them from seed last year. They are already 2 feet tall and growing like gangbusters, even in small pots. I will need to pot them up a size larger soon. These seedlings do not appear to be much affected by having a dry pot because they've dried out more so than the other seedlings with no apparent ill effects (mostly winter-sown perennials).

They also appear to be quite hardy, which I wondered about because the seed was from a tree at the Arnold Arboretum, which is a zone 6b/7a and probably one zone warmer than where I am. They were in pots outside all winter (with a mulch of leaves as protection) and came through unscathed, whereas I lost 6 or so other plants in the nursery, including some that had survived previous winters fine. This past winter seemed to be pretty harsh on borderline woody plants.

So based on the performance of the seedlings my guess, FWIW, would be that this species is somewhat drought-tolerant, and hardy and fast growing.

Here's a pic I just happened to take yesterday, 2 Katsura next to 2nd year Corylus americana and Cornus alternifolia seedlings:
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I've got a 10-yr old -- about 20' tall. It does indeed require extra care keeping watered first few yrs, but after that, mine has shown no unusual sensitivity to drought -- hasn't been watered for yrs.

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hairmetal4ever Z7 MD (My Page) on
Wed, Jun 4, 14 at 9:12

We rarely get severe and/or longer-term droughts here (maybe one a decade on average that will last a year or 2)
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Hair, I'd consider 2001 thru late August 2002 to be the last serious drought in western MD. In late August 2002 the drought began to reverse & 2003 was so wet some plants (especially corn, wheat, soybeans, etc) suffered from wet fields, lack of sun & fungal diseases.

I'd agree, beng - I didn't live here in '01/'02 but everyone says that was the last bad one. In 2010, 2011, and 2012, we started off each summer with a mild drought, but it seemed to end before fall, and I think at least a couple of those years ended up above normal in rainfall.

I lived in Ohio in 2003 and it was wet there, too (I think the entire eastern 1/3 of the country was wet that year). In July alone we got over 12" of rain in Akron.