Many shrubs benefit from heavy pruning during the winter months.
Called "rejuvenation pruning," this method involves cutting back all stems and branches to a height of 12 to 18 inches above the ground. It's a great way to make older, overgrown or "leggy" shrubs smaller, fuller and more vigorous.
Rejuvenation pruning can be used on a number of shrubs, including Texas ranger, oleander, jojoba, greasewood, senna, ruellia, red- and blue-flowering salvia and hopbush. It's also a must for our cold deciduous bird of paradise and Arizona bells.
On large shrubs with thick stems such as Texas ranger and oleander, use long-handled loppers or a pruning saw to cut the branches off 12 to 18 inches above the ground.
On shrubs with small stems, such as with ruellia and salvia, use hand pruners to cut the stems down. Don't worry about the severity of the pruning or how bare and stubby the shrub looks. Even if all the leaves are removed, in the spring vigorous new growth will sprout from dormant buds lining the base branches (stubs) and a dense, leafy shrub will quickly form.
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Shrubs with small, closely spaced leaves such as Texas ranger, senna, salvia, greasewood, ruellia and hopbush have closely spaced dormant buds lining the base branches. So you can cut them back at any point 12 to 18 inches above the ground. It really doesn't matter.
For shrubs with larger leaves spaced farther apart — oleander, deciduous bird of paradise and Arizona bells — cut the stems back just above an outward-facing bud if it can be found. On red and yellow bird of paradise shrubs, the buds are easy to recognize.
Just look for a small dark-colored raised bump along the stem. Find one facing out from the center of the shrub and cut the stem off just above it. When spring comes, this dormant bud will sprout and new growth will be directed out, keeping the shrub open and full.
To further stimulate new growth in the spring, apply fertilizer to rejuvenation-pruned shrubs in early March.
Apply one cup of ammonium sulfate (21-0-0), lawn fertilizer or similar analysis fertilizer to large shrubs you prune back. For smaller shrubs up to 3 feet, prior to pruning apply one-half cup of fertilizer.
Sprinkle the fertilizer evenly over the soil around the base of the shrub and out to about 4 feet. Immediately after applying the fertilizer water it in slowly, using a soaker hose.
After rejuvenation pruning, shrubs can be maintained using the heading back pruning technique: the selective removal of only the longest stems in order to shape the shrub and control its overall size. Individual stems are cut off back into the interior of the shrub. This is the best way to control plant size while maintaining the shrub's natural form.
Finally, keep in mind that it's still too early to prune back cold-injured shrubs like lantana and bougainvillea.
Wait until all danger of frosty weather has passed. In southern Arizona, that's typically mid-March in Tucson and early April in Sierra Vista. The new growth that emerges on stem and branches will show you what to prune away and what to leave.
» Tips on tomatoes
• "Growing Patio and Garden Tomatoes" will be the topic of this week's gardening demonstrations. Presentations are slated for 1 p.m. Wednesday at the Wilmot Library, 530 N. Wilmot Road, and 1 p.m. Friday at the Oro Valley Public Library, 1305 W. Naranja Drive.