Dwarf-size Plants Won`t Dwarf A Yard

October 21, 1988|By William Aldrich.

Even the fussiest of gardeners counts on certain plants to just be there- to grow through thick and thin, to resist disease and insect attack and to require an absolute minimum of upkeep.

To the vast majority who simply want to keep the neighbors from looking down their noses at us, that same low-maintenance feature is one of the most attractive attributes of a plant. Plant it and forget it except when someone wants to compliment you on it.

Evergreens have been a favorite answer to all those criteria, even though those cute little pine trees that were planted a foot or two from houses all over the area have now grown into gigantic monoliths, threatening to swallow the structure they were intended to complement.

One solution is a special group of plants that are known as dwarf conifers. These evergreens are mutated forms of the species and even at maturity are only a fraction of the size of their forest relatives. Once planted, they will not outgrow their location; and because they are smaller and have less of a root ball, they are much less susceptible to disease and insect damage that threaten the larger forms of the same shrub or tree.

But as with so many things in life, there are tradeoffs with dwarf varieties. One of the biggest is the initial cost, which may run to hundreds of dollars for a mature species that may be only 3 feet tall.

``They are more expensive for the initial cost, but from that point on there is a negligible cost,`` said Galen Gates, senior horticulturist at the Chicago Botanic Garden, at the recent dedication of the Glencoe facility`s Dwarf Conifer Garden.

Dwarf conifers don`t require the maintenance of a shrub, ``and a shrub has a finite amount of time to live,`` Gates said. ``It will live 10 to 15 years, approximately, and then go into decline; whereas most of these conifers are very long-lived, and you are not going to have a turnover if you live in a house 40 or 50 years. That plant will always be there.

``It will not outgrow its bounds, and you will have spent no money or labor to keep it in bounds, so it`s a cost-free plant.``

The Botanic Garden`s collection of nearly 400 dwarf conifers is interplanted with ground covers, ornamental grasses and some flowers on the back side of the hill that creates the elevation for the Waterfall Garden, the other major garden area opened this year.

Brian Barker, curator of the Dwarf Conifer Garden, said many of the specimens were started in the late 1940s at Longwood Gardens in Pennsylvania and are just now reaching their maturity. A Norway spruce in the garden is about waist-high and growing about a half an inch a year, Barker said. A nondwarf Norway spruce grows 40 to 60 feet tall and sometimes over 100 feet.

``Dwarfs don`t have a strong central leader,`` Barker said. ``Most dwarf conifers are compact, not overly dense. They are denser in the Northwest than here because they don`t get such hot summers.``

The Chicago area is native turf for very few conifers, Gates said. ``The unfortunate thing in this area is the heavy clay soils, and you get such extremes that the root system drowns in the spring and then it just bakes in the summertime,`` he said.

``What we try to do is promote planting a little bit higher, using at least 50 percent existing soil if it is a very bad situation and then (adding) amendments, because hardiness isn`t the problem, it`s the drainage, the lack of air and gas exchange in the root system,`` Gates said. ``It`s really a sad situation with the Scotch pine and the Austrian pine. The insect and disease problems just knock that group out as far as we`re concerned.``

Dwarfs cope better because their roots are not as massive and they usually come from clean cultivation, Gates said, meaning they are not as likely to be carrying a disease when bought from a nursery. In the Dwarf Conifer Garden, each bed has its own drainage system, and the soils have been custom-blended to best suit the evergreens.

Although many evergreens are planted for screening effects or hedges, the dwarfs work better as features in a mixed planting, grouped with other dwarfs or as specimens all by themselves. Gates especially likes the effect created by ornamental grasses in beds with the conifers.

``From a distance, it`s almost like a cloud in here,`` Gates said of the effect created by the Deschampsia, a summer-flowering grass that stands 3 feet tall. ``They are exhilarating to me. They provide some relief. You have evergreens that are stagnant structurally throughout the year; these come up and drop back down and provide color variation. They have fine textures, which go well with the conifers.``

Curator Barker describes the setting as a collection in a landscape setting. ``We tend to isolate them more than the homeowner and use a carpet of ground covers,`` he said.