Trees that will grow on gravelly soils:

Tree-of-Heaven (Ailanthus altissima).

Dahurian Birch (Betula davurica).

Common Honeylocust (Gleditsia triacanthos).

Nordmann Fir (Abies nordmanniana) will grow on gravelly hardpan.

Mimosa (Albizzia julibrissin).

Oregon White Oak (Quercus garryana).

Mugho Pine, or Swiss Mountain Pine (Pinus mugo).

Common Paper-mulberry (Broussonetia papyrifera).

Common Sassafras (Sassafras albidum (officinale).

Trees that will grow on dry, alkaline soil in the West:

Fremont Cottonwood (Populus fremonti).

Jujube (Zizyphus jujube).

Velvet Ash (Fraxinus velutina).

Trees that grow well on alkaline soils in the East:

Eastern Redcedar (Juniperus virginiana).

Franklinia (Franklinia alatamaha) prefers slightly alkaline, moist, but well-drained soil.

Beech (Fagus).

Trees that will grow on very sandy soil:

Australian Tea-tree (Leptospermum laevigatum).

Ailanthus (Ailanthus altissima) .

Smooth Arizona Cypress (Cupressus arizonica bonita).

Pfitzer Juniper (Juniperus chinensis pfitzeriana).

Savor Juniper (Juniperus Sabina) .

Creeping Juniper (Juniperus horizontalis).

Shore Juniper (Juniperus compacta) on sandy shores.

Jerusalem-thorn (Parkinsonia aculeata).

Mimosa (Albizzia julibrissin) .

Silk-oak Grevillea (Grevillea robusta) .

Pitch Pine (Pinus rigida) .

Scotch Pine (Pinus sylvestris).

FLOWERING BULBS prefer a friable, fertile, and well-drained soil.

They perform very well on sandy loams, loams, and even clay loams if drainage is good. The prevailing soil and air temperatures are greater limiting factors than soil type, because the type of soil may be amended, but we can do little about the weather.

High soil fertility is important with all flowering bulbs. Even in sandy soils, good results may be had if the soil is fertile. There is considerable evidence, however, that high levels of nitrogen (especially from organic sources such as animal manures) increase the activity of some soil fungi that attack and destroy flowering bulbs.

The problem of drainage is important with some bulbs. Many of the lilies (such as testaceum, candidum, and auratum) will not tolerate poor drainage. Others (such as pardalinum, parryi, and canadense) perform very well in wet soils if the soil moisture is not stagnant. Such conditions are provided at the edge of running streams or on slopes fed by springs.

There is very little evidence as to the acidity or alkalinity preferences of flowering bulbs. In general it appears that most bulbs perform well when the soil is slightly acid. Some lilies, such as speciosum, auratum, and philadelphicum, prefer soils more acid than candidum or longiflorum.

Until more acceptable evidence is available, it is impossible to make any definite recommendations regarding either optimum fertilizer or pH requirements of flowering bulbs.

HERBACEOUS PERENNIALS grow very well on a wide variety of soil types, if the soil is well drained. Sandy loams, loams, and silt loams usually meet the requirements of good drainage. Sands and loamy sands also are satisfactory, but they may require frequent applications of water.

Since the perennials will occupy the space for several years, it is important to put the soil in a good state of fertility before the plants are set out.

Unfortunately, little scientific data are available as to the preferable soil types or fertilizer requirements for the numerous kinds of perennial ornamental plants available to gardeners.

More information is available as to the effect of acid or alkaline soils on growth of some perennials. Even here, however, there is very little in the way of experimental data comparing plant response when grown under a wide range of acid or alkaline soils. Most perennials appear to perform best when the soil is slightly acid.

GOOD ANNUAL FLOWERS may be grown on a wide range of soil types. Because many of these plants are shallow rooted, good drainage is less essential for them than for bulbs and perennials. Light, friable soils, such as sandy loams and loams, will produce good annuals.

The length of the growing season and the air temperatures are of prime importance in growing many annuals. The range of such annuals as stocks (Matthiola incana) and sweetpeas (Lathyrus odoratus), depends on cool air temperatures rather than soil type.