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Garden wisdom from deer country!

Gardening in the Sierra Foothills with Carolyn Singer

Get to Know Your Plants
Irrigate plants when they REALLY need it!

By Carolyn Singer
August 1, 2009

Buddleia x pikei 'Hever Castle'A walk in your garden each day may serve you well. Besides the obvious benefit of connecting and relaxing, observing plants may even save you water.

Learn the feel of leaves when they are hydrated, especially if you have added this plant to your landscape within the last year. Wilted leaves are obvious, but the trick is to observe the stress before damage is done to the plant.

In our sunny and dry foothill climate, plants lose a lot of moisture on a daily basis. If rainfall or irrigation meet the needs of the plant, it will still perform well. However, if the plant does not get the water it requires, it may wilt, lose leaves, reduce growth, and even die partially or totally.

The solutions to the challenges of growing plants in the foothills are: 1) choose the right plant, 2) know the plant's needs, 3) prepare the soil optimally, 4) mulch to protect the soil surface and conserve moisture, 5) irrigate deeply and only as needed, and 6) zone your landscape, grouping plants with similar needs together.

Consider the natives in our region. In some rainfall seasons they do not receive optimal moisture. For this reason, most natives often have far less moisture in their foliage by late summer. If the landscape near your house includes natives that have not been irrigated since the last rain, a deep soaking now will be beneficial. And while you are addressing fire risks, recheck the defensible space surrounding your home: is it the required 100 feet?

A recently planted native may need regular irrigation in the heat of the summer for the first year or longer. A good example is an incense cedar (Calocedrus decurrens). This native even benefits from irrigation every summer for the first five years. The native bleeding heart needs a little summer irrigation the first year. However, if it is watered regularly each subsequent summer, it will die. Know your plant.

Years ago I planted my first Matilija poppy (Romneya coulteri) in July, watered it deeply, and have never watered it again. A Newcastle reader recently shared with me that he waters his stand of Matilija poppy and it blooms longer. Of course he is at a lower elevation with a south by southwest exposure, and the plant is growing on a rocky slope. Know your site.

leatherleaf viburnumSome of my favorite non-native ornamentals need little or no irrigation once established: leatherleaf viburnum, 'Hever Castle' butterfly bush, English hawthorne, silverberry, and variegated holly. These are grown in my dry zones.

Encourage strong roots with ample compost and organic phosphorus added to the native soil. Deep-rooted plants need to grow in deep soils. Plants with strong root systems need less water.

Mulch deeply with a material that holds moisture for plants that need regular irrigation. Containers with annual flowers or vegetables may be mulched too. Decomposing straw makes a perfect mulch for many plants, protecting the soil surface from sun and wind, and extending the periods between irrigations.

When it is necessary to irrigate, water deeply and only as needed. A tomato plant with a three to four-inch straw mulch may need water twice a week when it is growing actively, and may need water only once a week when it begins to develop fruit. Check in the morning: if the foliage is not wilted, hold off on watering. While it wilts at the end of a hot day, so do you.

©2009 by Carolyn Singer. All rights reserved.

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