This article is about one of my favorite conifers, the Yew. Little is written about Yews in the bonsai literature and they are much underused for bonsai.
The yew or Taxus family, consists of evergreen plants with small needles, colorful bark, excellent survivability under pot culture, good response to wiring, and a durable wood suitable for jin and shari. Individual yew plants are either male or female. In the fall females bear small red fruit and are thus easy to identify. When not in fruit the flower buds of female plants are small droopy spheres; the male flower bud is twice as large and held more upright.
Seeds and needles are poisonous, while the flesh of the fruit is not. Yews are extremely toxic to horses. In areas of northern Michigan the native Yew, Taxus canadensis, is nearly impossible to find since the resident Moose population finds it very tasty and apparently not toxic. Just to be on the safe side I would recommend not eating any part of a Yew.
Normally Yews grow upright or in a spreading low form, and they may have single or multiple trunks. In a Japanese park I discovered a Yew that had a trunk diameter of four or five feet! Our native Michigan Yew is a shrubby plant that is not very good as bonsai material since it is quite shrubby and does not form a single trunk. In England there are huge and ancient Yew specimens which are much revered for their long life and religious associations.
Yews are cold hardy and used extensively in our area for landscaping. The best way to secure bonsai material is to rescue a plant from an older home that is being re-landscaped, or buy one from a nursery. The trick is to let friends and neighbors know of your interest and volunteer to dig them out when they re-do their homes. The best bonsai are created from plants with one good sized trunk rather than multiple slim trunks. Reject plants without interior foliage as yews may be reluctant to "break back" foliage on older wood. A yew with several stems can be utilized for a group or clump style planting.
Landscape material is collected in spring after frost has left the ground. Collecting plants in mid-summer after the new foliage has hardened off can also yield excellent success. Fine fibrous roots are invariably found close to the trunk and the retained root ball need only be six to ten times the trunk diameter. Keep in mind that yews often have their largest trunk diameter below the soil surface, so do not automatically reject a slightly slim trunk without exploring below ground.
Initial pruning on a collected yew ideally should leave about 40-60% of the starting foliage. If more foliage is cut away the plant may suffer or even die. Grow the tree in a container or ground bed for a year or until good vigor is apparent, then more trimming back can be done. As with a pine, always leave green foliage on a branch or there will be no foliage regrowth. Yews are peculiar because they may retain live cambium for years on a branch after all foliage has been removed from it. This branch probably will never resprout foliage, and eventually the cambium will die back.
Achieving new foliage sprouts or "back-breaks" on wood over 30 years old is not a certain event and has proven impossible on some of my trees. Yews grow only from existing buds or needled areas, but some trees may sprout new buds on 50 to 60 year old wood. In my experience this occurs on healthy, vigorous trees especially female plants grown in full sun.
Yews tolerate - if not enjoy - pot culture, and will tolerate most soil mixes. Yellowing of foliage indicates wet soil or high acidity so let the soil dry more and add bonemeal to the soil surface for a quick shift back to elegant dark green foliage. Fertilize with the usual routines and they will remain healthy and vigorous. Repotting is a job needed at least every three years. Yew roots are fine, numerous and hairy and will quickly block any open spaces in the soil mix.
Disease and insects are almost never a problem with Yew plants.
Yews tolerate some shade, but for good growth and "back-breaks" on old wood grow them in full sun. Some yews will break buds back on old wood while others will not. Female plants seem to break back more easily than male, and younger trees are more reliable in breaking back. Once the bark of the yew has exfoliated back breaks are much less likely unless there are pre-existing buds visible.
Yew wood is dense, resists rot, and these factors are important when doing jin and shari work. Wood and cambium are nearly always vertical in nature, therefore jin will not naturally spiral around the trunk. Creating a spiral shari is done by connecting small man-made wounds, enlarging, and connecting them gradually over a series of years allowing the plant time to establish new sap channels.
Carving or grinding out substantial quantities of wood on a yew will require determination, perseverance and some hefty power tools. To reshape a large yew several hours of grinding will be necessary with a chainsaw, die grinder or right angle grinder. A "dremel" tool is too puny unless there is only surface texturing to accomplish. The extremely dense wood resists all but the most powerful tools and carbide bits. Regular bits lose their edge in minutes.
Once the wood is shaped it is necessary to preserve the wood. After wetting the stripped wood apply full strength lime sulfur. This allows the lime sulfur to penetrate more easily. Paint pigment added to the lime sulfur will allow the color of wood to suit your taste.
Yews have extremely handsome red to brown sub bark and this may be exposed by picking at and removing the dark brown shaggy outer bark. This is easily done after several days of rain have softened and lifted the old bark. Do not peel into the green cambium layer. Jin and shari contrast beautifully with this red-brown sub bark.
Despite dense wood, large branches on a Yew can be bent fairly easily. Branches over 1" in diameter can be shaped by using raffia to protect the bark and then wiring with heavy wire. Wiring during early summer requires caution as the bark may slip at this time. If bark is slipping stop immediately and do not wire for several weeks. Even thicker branches can be lowered by overcutting the branch at the trunk junction and then carefully bending the wired branch down.
In conclusion, the Yew is a tough plant which is extremely suitable to bonsai, and should find more frequent use as a bonsai subject.