Wednesday, April 7, 2010

Living with Low Water Plants, Part 4: Plant Maintenance

Of all the important factors contributing to overall plant health in the urban garden, none is so overlooked as timely pruning, cleaning or thatching. Plant maintenance can be an energy intensive and sometimes meticulous process, as in the case of plants which require selective pruning.

With almost all plant species, regular pruning is a sure way to promote more abundant flowering cycles, aesthetically pleasing form and better overall plant health. 

Everyone has seen the stereotypical gardener walking from plant to plant with a power hedger. One of our inside jokes goes like this: Since the power-hedger is typically hooked into a belt loop, if you want the hedges higher, you'll need to higher a taller helper. In reality, hedging most plants (save for actual Boxwoods) typically catalysis a decline in plant health as the process of continually tip-pruning a shrub can create an almost impenetrable canopy of small leaf growth. This dense tip growth can eventually filter-out the needed light and air circulation and the interior of the plant can become dry and brittle. With regular pruning and cleaning, plants get the air and light they need to regulate normal photosynthesis and the plant lives longer, looks and performs better.

In this short chapter on Living with Low Water Plants, we will be briefly discussing a few key points surrounding the concept of regular plant maintenance as a component in the successful management of any low water garden.

 Evergreen vs Deciduous: Know Your Plants Before Pruning
The definition of Evergreen: 
1 : having foliage that remains green and functional through more 
than one growing season 

The definition of Deciduous:
1 : falling off or shed seasonally or at a certain stage of 
development in the life cycle 
-Merriam-Webster's Dictionary
It would be rather unwise to generalize about pruning "all plants" as a single group because each plant will have its own specific needs due not only to its own genetics but also due to other associated environmental considerations such as position in the garden, sun/light exposure and proximity to other plants. In our experience, many flowering shrubs can be induced to three or even four flowering cycles with regular pruning, whereas the un-pruned plant of the same species and general location in the landscape may only flower once, or twice, if at all.

What we can offer by way of advice with reasonable safety (for the plants, that is) are some general pruning tips and rules of thumb to consider before tackling that large flowering shrub that has been calling you from out in the yard. At the end of this section, we will also be including a small but useful pruning schedule for many of the low water plants we use in our own Gardens & Garden Designs.

Some General Pruning Tips:
  • Clean tools after pruning each plant; We use a combination of Dr. Bronner's Peppermint Soap and Isopropyl Rubbing Alcohol of at least 70% to kill bacteria

  • Sharpen tools between plants; Have a sharpener on hand at all times and sharpen your tools at the same time you are cleaning them. Sounds like alot of work, but it helps to prevent spreading diseases between plants

Other Rules of Thumb and Common Techniques in Review
  • Prune deciduous shrubs and perennials during dormant period to prevent 'bleeding' or seeping, which can attract insects and in turn, kill the plant

  • Prune old stalks prior to new growth which invigorates the plant and forces the plants energy to produce new growth in Spring.  Do not prune these plants in December or January as the existing foliage helps retain warmth during the cold winter months; see plants under 'February-March Pruning List'

  • Prune after flowering to keep plants from getting overgrown, spindly, or weak; see plants under 'April, May, June Pruning List'

  • Coppicing:  If your plant is completely out of control, has overgrown its space, or is woody and spindly, you may be able to coppice, which is a way to prune to renew your plants vitality.  By cutting to the ground completely during winter, you stimulate vigorous new growth; see plants under 'Coppice; February Pruning List'.
Seasonal Pruning Schedule
Below is a list of a few common shrubs and perennials found in California 
gardens and their pruning schedule for Spring through Summer:
February-March Pruning List:  
Abelia grandiflora (Glossy Abelia), 
Abutilon (Flowering Maple), Agastache (Hummingbird Mint), 
Artemisia (Wormwoods), Asclepias (Butterfly Milkweeds), Asters, 
Berberis thunbergii (Japanese Barberry), Buddleia (Butterfly Bush), 
Carpenteria californica (Bush Anemone), 
Cotinus coggygria (Smoke Bush), Epilobium (California Fuchsia), 
Eriogonum cinereum (Ashyleaf Buckwheat), Lantana, Salvia leucantha (Mexican Bush Sage), Mimulus, Nepeta (Catmint), 
Penstemon (Beard Tongue),  Perovskia (Russian Sage), 
most Sages (Salvia), Santolina chamaecyparissus (Lavender Cotton), 
Sedum 'Autumn Joy' (Stonecrop), Spiraea japonica 'Goldflame' 
OK to Coppice in February:  
Abelia grandiflora (Glossy Abelia), 
Berberis thunbergii (Japanese Barberry), Buddleia (Butterfly Bush), 
Carpenteria californica (Bush Anemone), Cotinus coggygria (Smoke 
Bush), Epilobium (California Fuchsia), Perovskia (Russian Sage), 
Sedum 'Autumn Joy' (Stonecrop)

April Pruning:  
Coleonema (Breath of Heaven), Correa, 
Hardenbergia violacea (Vine Lilac)
May Pruning:  
Choisya ternata (Mexican Mock Orange), Cistus (Rockrose)

June Pruning:  
Ribes sanguineum glutinosum (Red Flowering Currant), 
Rosmarinus (Rosemary), continue to deadhead all plants throughout 
the summer 
See more in our Living with Low Water Plants series:
Part 1: Plant Installation
Part 2: Using Drip Irrigation
Part 5: Holistic Economics

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