December in the Crystal Springs Test Garden
Ruth M. Hansen, Portland, Oregon
All activity in the Test Garden this Fall has been centered around the Coolhouse. It was some little time before the Heating and Ventilating systems were completed due to the red-tape involved before the City would approve our plans. After final approval, then came the long drawn-out process of getting construction bids from various electrical companies, but finally the job was let and the work soon completed. The Coolhouse itself is a room 40' x 40' and 21' high. It is covered with a corrugated plastic material known as Filon.
The heating system consists of two automatic electric heaters suspended from the center of the building, each facing an end wall. The thermostat is set at 38 degrees F. Many of the plants are really quite hardy and could stand a much lower temperature, but others are bud-tender, therefore to be on the safe side we selected 38 degrees as our fluctuation point. As the building retains what little solar heat we do get during these dark winter days, it hasn't been necessary for the heaters to function too much at this time. The two ventilators, located high up on each end wall are the louver type and are set to exhaust the air when the temperature reaches 85 degrees, thus these will operate only during the summer months.
The fine collection of the tender varieties of rhododendrons, which had been billed-in during the summer were brought into the Coolhouse by the first of October. These plants are all potted in a mixture of ⅓ loam, ⅓ peat moss and ⅓ sand and planted in redwood tubs. As the maddenii and edgeworthii varieties are all epiphytes in their native habitat, growing high on the branches of trees in the sub-tropical rain forests of Western China and Upper Burma, they naturally have very poor root systems and a tall rangy plant will often go into a 6" tub. It was thought best to keep the majority of these plants in tubs rather than to set them out permanently in the ground, so that they could be moved around to greater advantage during our Annual Show and to move them outside during the summer, if necessary. The floor of the Coolhouse is covered with two feet of fir sawdust, (Pseudotsuga taxifolia) and the redwood tubs are sunk directly into this; however our two 8' specimens of R. nuttallii and R. polyandrum and R. dalhousiae are planted directly into the ground as they are much too big to handle in tubs.
There are some 75 rhododendrons now in the Coolhouse making a fine representative collection of the Maddenii, Edgeworthii and Boothii series. While recently checking over this collection, it was most gratifying to see how well budded they were. R. ciliicalyx, R. parryae, R. formosum and R. lindleyi to name a few will put on a grand show beginning in February and lasting through May that will delight everyone, not only by their lovely flowers but by their delightful spicy fragrance unknown in other rhododendrons.
Anyone can grow the usual hardy rhododendrons outside, but very few have the opportunity to acquaint themselves with these more tender varieties. The Coolhouse was constructed as an educational project for everyone to enjoy and we hope that it will be well used as the plants begin to flower.
As it is now past the middle of December, the winter color in the Test Garden is becoming apparent. For a rich bronzy color there are few plants that can surpass 'Broughtonii Aureum'. Those who are unacquainted with this azaleodendron are often alarmed, and think their plant dying when first seeing its leaves turn brown, but as the season advances, the richness of the color becomes alive and creates a vivid, warm winter picture lasting till spring. Along the south side of the island are the large plants of R. occidentale, (Western Azalea), though deciduous carry their flamboyant colors through December. To the right of the path is a planting of the evergreen azaleas now coming into their winter fineness in shades of deep copper and wine-reds. These make an excellent border to the deciduous Ghent and Mollis varieties long left naked by a heavy wind storm. On the West side of the Island one finds the ever beautiful R. bureavii, beautiful as to foliage whether in new growth or old. At present its leaves are a dark blue-green color off-setting its marvelous indumentum. R. smirnowii is another good winter foliaged plant as its lovely white, woolly under-surface is always in evidence and presents a pleasing green and white effect. Nor can we overlook R. metternichii whose each set of leaves tiered above the preceding one give an effect of many tiny open umbrellas, dark glossy green above and golden brown beneath.
Possibly, one can see the greatest color contrasts at this time of the year in the Rock Garden. Here the Lapponicum group really puts on a winter show all by themselves with colors ranging through the various shades of deep reds, purple, bronze and deep blue-greens. R. impeditum, R. russatum, R. intricatum, R. scintillans all vibrate with a new life and color during these dark months and viewed en masse they create a very effective winter landscape. The deciduous R. trichocladum now at its very best in its dark red and wine-colored foliage blends beautifully with the Lapponicums. Among the other dwarf varieties found in the Rock Garden are R. williamsianum and its many hybrids which cannot be overlooked for their wonderful year-round effect. Now in the middle of December, they are as perky as ever and their little heart-shaped leaves and reddish-brown buds give a very neat and clean appearance to their area.
While walking through the Test Garden at this time of the year, one cannot fail to be impressed by the excellent condition of all the rhododendrons and azaleas. Practically every plant has put forth the heaviest bud-set we have had in the six years of the garden's existence. The bed of R. Elizabeths consisting of a planting of some 40 plants 9" to 12" in height will be a riot of color in the Spring. And the large planting of R. "Azor" at the south end of the island are literally covered with buds, so are the R. Naomi hybrids and nearly all other varieties as well. The Azaleas, rhododendrons, species and hybrids will really be at their best this spring providing some unforeseen climatic disaster doesn't strike. The evergreen azaleas which were so badly hurt by that un-seasonal freeze of November 1955 have made a wonderful recovery and many are going to bloom again this spring.
Regarding that freeze of 1955, the garden did lose a number of plants, such as R. 'Cornubia', 'Mayday', 'Beacon', 'Goblin', some plants were defoliated as R. 'Penjerrick', 'Cornish Cross', cinnabarinum hybrids and those in the heliolepis series, but these are now coming back. Possibly our greatest loss was to the grouping of the large R. falconeri, R. fulvum, R. arboreum and the beautiful specimen of R. spinuliferum. These are losses not easily replaced and it will be years before the garden can grow plants large enough to take their places.
A paradox to be noted as a result of that freeze is that all the small plants of the large-leaved varieties of the Rock 1950 seedlings had been moved just a week previous to the freeze and none of these plants were lost, though they were hurt a bit; yet all the large plants of R. falconeri and R. fulvum were killed. We have concluded from this that by moving the small plants, we stopped the growth and introduced a temporary dormancy while the others were in full lush growth due to the long wet fall.
Some work was done this fall in continuing the planting on the new peninsula, north of the entrance to the Test Garden from which it is separated by a 250' foot bridge. There were 26 large rhododendrons donated and these were set out in this area to extend the planting down through the woodland. The largest plants were two 8' tall and 8' wide R. 'Mrs. A. T. de la Mare' and it was a Herculean task to transport these plants from the parking area down across the high bridge and then onto the peninsula.
The soil on this tract is virgin, black loam built up from centuries of decaying vegetation and like the Test Garden, the rhododendrons planted here will need no fertilizer for many years. The native material is similar to that on the island, consisting mainly of Douglas Fir, Western Red Cedar, Big Leaved Maple, Vine Maple, Western Dogwood and a few Cascara. The outer edges are banked with willow, creek Dogwood and Wild Blackberry providing sanctuary for the wild ducks which are given refuge in this lake.
The Trial Committee has set the following policy for the Test Garden. The gates are opened from the middle of March to July, from 11:00 a.m. till dark each day, at which time a park attendant is on duty. During the late summer, fall and winter months when there is little bloom the gates are kept locked. The Coolhouse will be open to the public at designated hours, but these so far, have not been determined.