Northern Catalpa tolerates a wide range of soils, including pH in the 7’s, and is moderately drought-tolerant. It is a tough tree suited for planting in large-scale landscapes. Catalpa often escapes cultivation and invades surrounding woodlands. It is a tough plant that can grow about any place including sidewalk cutouts and could be used more. Catalpa speciosa grows in a loose oval, 50 feet tall in most urban locations, but occasionally grows to 90 feet. Plants in containers tolerate moderate soil salt solutions up to about 4 mmhos/cm according to the saturated media extract method.
This coarse, large leafed tree spreads 45 feet and tolerates hot, dry weather, but leaves may scorch (especially cultivars with variegated foliage) and some drop from the tree in very dry summers. Expect one and two year old twigs on the ground after a summer thunderstorm or following windy weather. Fruit litter the ground in spring. The pretty flowers are produced a couple of weeks before C. bignonioides and they attract bees. One reference says pollen can cause significant allergies; another one says they do not cause allergies.
Wood was used for railroad ties and fence posts in times past.
Plants can be cut back to the ground each year to act like a perennial. The vigorous growth produces large leaves and a rich tropical effect in the shrub border.
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