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Drought Response

Filoli’s planned water conservation measures and recommendations.

Blooming Calendar
Blooming Calendar

Find out what's blooming at Filoli from January to December.

Garden Information

Learn about Filoli plants and gardening practices—ask the experts.

Jazz at Filoli

Our 24th season of talented artists on the Jazz stage.

Plant Highlights This Week

Flowers are one of the most pronounced markers of the progression of time in a garden. Each month we scout the Garden for amazing blooms and feature our favorites here. Check back often to see what we have in store for your next visit to Filoli.

Spider flower in the Sunken Garden in the evening light. Photo by Michael Thompson.
Silver lace vine growing on wall adjacent to Garden House.
Begonia plants in Chartres have filled in nicely.
Zinnia haageana ‘Aztec Burgundy Bicolor’ in Walled Garden.

Garden Happenings
Week of August 18 – August 24, 2014

New Plantings:
No new plantings during the peak of summer beyond the occasional addition to the Cutting Garden as plants become ready.

Plant of the Week:
This week’s featured plant is Cleome (formerly spinosa) hassleriana ‘Queen Mix’, which is found in the four outer corners of the Sunken Garden. These tall (4-6’) annuals are known as spider flower because of their spidery flower heads, as well as their spidery seedpods that subtend the flowers. The ‘Queen Mix’ has flowers in white, pink, rose and purple shades. Spider flower is a wonderful old-fashioned cut flower, and makes a nice back-of-the-border addition to annual and mixed perennial beds.

Botanists have recently placed Cleome in its own plant family, the Cleomaceae, but until recently, it was in the Capparaceae, the family that includes the Mediterranean native Capparis spinosa, from which capers are derived. There are several California natives in the Cleome family, including the bladderpod, an attractive shrub with yellow flowers and showy, inflated seedpods.
As gardens age, we are forced to respond to woody plants that are facing the end of their road. The latest tree of concern in the garden is the stately oak between the Dutch Garden and the Walled Garden lattice area, home of the purple, blue and white hydrangeas. The vigor of this old, coast live oak (Quercus agrifolia) has been decreasing for at least a decade and over the past few years has been displaying some significant disease issues and has reached the point where we are very concerned.

Most recently, a large fungal growth arose from the base of the tree on the east (Dutch) side. This organism is called weeping conk (Inonotus dryadeus), and like the more common shelf conk (Ganoderma applanatum), is an indication of root and buttress rot. Prior to this, large clumps of oak root fungus (Armillaria mellea) have grown from the west (hydrangea) side of the trunk. And on top of this, where the two major scaffold branches arise from the trunk, there is an accumulation of soil and other debris at this crotch, which often is indicative of a lack of solid structure.

We plan to undertake further investigative work to thoroughly validate the problems. With this triumvirate of serious issues, the outlook is not good. At the very least, we will plan to heavily reduce the weight of the north scaffold branch, which is the more weakly attached, to reduce its weight.

There is a strong possibility that the tree may need to be removed. Removal will be a significant job and come at a significant cost, since all the wood will have to be cut up small enough to haul out of the garden through the garden gates. It will also mean that this part of the garden won’t be in 100% shade anymore. Fortunately, there are other large trees (southern magnolia, New Zealand black beech) around the tree that will continue to shade many of the plants. We will keep you posted with further details as they arise.

Plant Highlights:

All of the summer plantings are well established and filling in nicely. Almost all of the beds are showing nice color. For the next two months, the annual beds should be at their prime. Later in the season, some of the more perennial type plants will carry the garden through the end of the season including the “queens of the fall garden”-- the dahlias.

The dahlias in both the Cutting Garden and Sunken area have begun to bloom.

The hydrangeas are absolutely gorgeous right now. In particular, the bed adjacent to the Walled Garden shop and the southwest corner of the panel garden are laden with blooms. The range of blues and purples just boggles the mind!  See the section below for more on the science behind the colors in hydrangeas.

Roses-Roses-Roses!  The Rose Garden continues to delight. In most years, the rose plants seem to pause around early summer. This year, while some plants are taking a break, many of the roses continue to bloom and look spectacular.

Many summer-blooming shrubs and vines are blooming including the Chilean jasmine (Mandevilla laxa), silver lace vine (Fallopia baldschuanica), pomegranates, and star jasmine.

The Kitchen Garden is looking quite bountiful right now. The pumpkins have begun sizing up, tomatoes, beans and peppers are fruiting, purple cabbages are making heads and gourds are beginning to hang from the gourd house.

The annuals and perennials in the Cutting Garden are looking impressive. Some of the best bloomers right now are the grasses, broom corn, zinnias, Chinese asters, Rudbeckia, and many others. We have cut the English lavender which will be used in products sold at Holiday Traditions.

Garden Projects:
Fruit picking began two weeks ago with some of the early apples, like ‘Gravenstein’ and ‘Pink Pearl’, and the ‘Bartlett’ pears. Moving forward through the harvest season, we will be picking fruit as it becomes ripe, culminating in the Autumn Festival (September 27) when dozens of fruit varieties will be available for tasting as well as for show. Recently, about 600 pounds of our fruit is being delivered to Hurley Farms in Napa. They will be transforming the apples and pears into fruit butters that will be available for sale beginning at this year’s Autumn Festival and Holiday Traditions.

Notes and Common Questions

  • Olive Renovation
    Another tree that has been in decline is the olive across from the Lock and Key sculpture near the front drive. The top of the canopy was mostly dead, probably from Verticillium wilt, while the lower trunk and roots were still quite vigorous. Olive trees are good candidates for renovation when they are too vigorous or lack vigor and this technique of cutting the tree back to six feet is often employed in orchard management. Our plan is to retrain the sprouts that emerge into a new, healthy canopy. The fencing added around the tree is to keep the deer from eating the sprouts as they emerge.

    Southern Magnolis
    A plant the horticulturists, and volunteers as well, are being asked about recently, concerns the stunning southern magnolia (Magnolia grandifloria) guests encounter as they approach the house and garden from the Visitor’s Center. This magnolia, one in the collection of magnolias added to the front of the house by Mrs. Roth, often introduces visitors to the high horticultural standards for which our gardens are known. (I can still remember seeing the tree when I visited Filoli for the first time on a rainy, spring day in 1994.) The question is in regard to the thinning canopy on the southeast side of the tree. The branches are not as full and the color is a bit off from the rest of the tree.

    The short answer is that we are still unsure what is causing the lack of vigor. We had wood samples tested from the top of the canopy, and nothing came back conclusive. Visually, the condition looks more like a Verticillium wilt, but none of the samples showed it was this fungal pathogen. We also had the roots tested, which showed Phyophthora, a root rot fungus, but this is common in our soils, and would show symptoms throughout the canopy.

    Recommendations we’re received, and the actions we are taking include giving the tree supplemental water through the summer and composting under the canopy. We’ve increased the water the past few weeks and plan to mulch with 4” of compost in the coming months. We’re hopeful that with some TLC the tree will grow out of the condition and begin to fill back in over time.

    Drought Update
    The Filoli drought page is on our website (http://www.filoli.org/drought/). As many have noted upon visiting this summer, many of our lower-profile lawns are somewhat to completely brown. We’ve also reduced our water use in our orchards and any other woody plantings by approximately 40%. We felt that these two major reductions in irrigation use would be the best ways we could do our part in conserving water along with everyone else in California. At this mid-year point, Dave Herrington, head of our maintenance team, reports that we have reduced our total water use by over 55% over last year!  Considering that last year was the driest calendar year on record, and that we had no conservation plan in place, with our use up approximately 25%, the outstanding savings this year might be somewhat inflated. That said, looking back to 2012, we’re still probably saving 45-50% over a typical rain year.  

    “New” Garden Room
    When Mrs. Berenice Spalding, one of the Roth twins, passed away last year, a bequest was made to Filoli on her behalf. Mrs. Spalding wanted her donation to be used on lasting improvements to the house and/or garden.  Cynthia approached Board member Denise Bates (daughter of Lurline Coonan) with the concept of a garden space honoring the Roth Children. Filoli staff and the governing board agreed that a new seating patio under the persimmon tree in the Rose Garden was the best fit. Denise, who is a landscape architect, designed the new patio. The rectangular patio surrounding the persimmon tree will be laid with two patterns of brick separated by a frame of bluestone. In the center of the patio, a medallion with FI-LO-LI, like the one above the Filoli Gate, will be at the center, surrounded by the names of the three Roth children: William, Lurline and Berenice. Three benches are being built for the patio, and three large terra cotta containers have been purchased. Construction of the patio should begin in the next month and it is hoped that it will be completed by Mrs. Coonan’s 94th birthday in August.

    The Colors of Hydrangeas
    In the wild, Hydrangea macrophylla, which is native to Japan, has pink flowers. Over the last century, different cultivars (cultivated varieties) have been bred to have darker pink, blue, or white flowers. To understand color change in hydrangea flowers, we have to delve into some basic chemistry. Hydrangeas prefer a slightly acid soil (pH 6.0-6.2). At this pH, hydrangeas will maintain their original color. As the soil approaches neutrality, and then becomes alkaline (above pH 7.0), and aluminum becomes less available to the plant, and thus, the pinks will become darker pink and the lighter blue shade will turn pink. In acid soils (lower pH), the pink flowers will become blue and the pale blue will become dark blue or purple. The exact shade of blue depends on the original color, how acidic the soil is and how much aluminum is available to the plant. White flowers will not change color with changes in soil chemistry.

    At Filoli, to acidify our soil and enhance the color of our blue hydrangeas, we add one-quarter to one-half pound of granular aluminum sulfate around the base of each large plant in November. If your soil is in the neutral range, it is fairly easy with the addition of aluminum sulfate to enhance the blue color in hydrangeas. It is much more difficult to achieve an alkaline soil, but this can be done by adding dolomitic lime several times a year around your plants. If your soil naturally runs acid or alkaline, it can be extremely difficult to sway your soil to the opposite end of the spectrum.  

    For more information on Filoli’s hydrangea care, please see the Garden Resource Center page of the Filoli website (http://www.filoli.org/garden-reference/). Here you will find a reference sheet on hydrangea care, many other Filoli plants, as well as other garden maintenance situations.

    Bloomin' Bucks Program
    Whenever visitors, volunteers or anyone else asks about where Filoli purchases our bulbs, after telling them that the bulk of our bulbs are purchased wholesale from the Netherlands, I tell them the best retail vendor in the US that I know is Brent and Becky’s Bulbs. Brent Heath’s family has long been in the bulb business and because of their lasting relationships with the Dutch growers, Brent and Becky are able to sell top quality bulbs. If Filoli could afford to buy all of their bulbs from this company, we would.  

    As part of the company’s commitment to public gardens, schools and other non-profits, Brent and Becky established the Bloomin’ Bucks program. With each purchase from Brent and Becky’s through the program, the designated non-profit receives 25% of the funds. Filoli is a participant in this program. So, if you’re planning to order bulbs this year, and like Brent and Becky’s products, please go to the Bloomin’ Bucks page (www.bloominbucks.com) to start your purchase by choosing Filoli as your non-profit of choice. From there, you will be sent to the regular Brent and Becky’s Bulbs website to start your shopping.


Written by Jim Salyards, Filoli's Manager of Horticultural Collections and Education, and Internship Program Coordinator