Norway spruce vs White spruce

In the lowlands and hills of Central Europe Norway spruces are dying in large numbers after the hot, dry summers of recent years, in gardens and parks too: the shallow-rooted, drought-weakened tree is attacked by the spruce bark beetle (Ips typographus), which cuts off the flow of water and nutrients under the bark, and an infested tree cannot be saved and should be felled quickly. In dry, warm spots spider mites and the green spruce aphid (Elatobium abietinum) also cause needle drop, adelgids distort the new shoots, and weakened trees get needle cast, canker and root and butt rot (Heterobasidion). Do not plant the full-size species on dry, poor soil, in city gardens or on the plains, and remember that a planted-out rooted Christmas tree becomes the same large, demanding tree. The dwarf forms need moist soil and summer watering just the same, but being small they are easier to water and mulch.

The worst enemy of the dwarf forms is spruce spider mite, which infests the dense, poorly ventilated cones in hot, dry sites (next to a wall, fence or paving): needles turn speckled yellow, then brown and drop, and the bare brown patches never green up again. Tap branches over white paper in spring and early autumn and treat in time when mites appear. It copes badly with the hot, dry summers of Central Europe and browns without watering; in winter drying wind and reflected sun can scorch the needles on the sunny, windy side. It sometimes reverts to the species: cut out any vigorous, fast-growing shoot with longer needles at its base or it will outgrow the dwarf part (on the coloured cultivars also any shoot reverting to green). Weakened plants can also get a needle cast fungus. It dislikes polluted city air and road salt as well. Shops sell almost only its dwarf or columnar cultivars, which stay a fraction of the size of the species: check the size of the cultivar you choose before you buy.