The key to successful planning for almost all flower bulbs is site selection. The major factors that must be considered are:
The soil at the site must be well drained! This is a critical factor for planting flower bulbs. The easiest method to determine if the site drains well is to observe the proposed planting area the day after an intensive rainfall. If water remains in the site, then the soil does not drain adequately. Therefore, either another site needs to be selected or the drainage needs to be improved
Check soil pH of the site! Once drainage in the site has been assessed, test the soil for the pH level. It should be within a range of 6 to 7. If necessary, adjust the pH level.
Check for perennial noxious weeds! Determine if the site contains weeds such as nutsedge (Cyperus spp.), quackgrass (Elytrigia repens), bermudagrass (Cynodon dactylon), or Johnsongrass (Sorghum halepense). If present, they must be eliminated before any ornamental plants, including flower bulbs, are used.
Check for proper light conditions! Depending on the genus, flower bulbs perform optimally under different light conditions. When De Hertogh and Le Nard (Chapter 6, The Physiology of Flower Bulbs, 1993, Elsevier Science Publishers, Amsterdam) reviewed the literature on light requirements for outdoor usage of flower bulbs, they proposed that five classes be used. This system is used in this Bulletin. The five light conditions are defined as follows:
The higher light intensities are preferred for Northern Climatic Zones (3 to 6) and the lower light intensities for Southern Climatic Zones (7 to 11).
A microclimate is the local modification of the general climate that is imposed by the special configuration of a small area. It is influenced by topography, the ground surface and plant cover, and man-made forms. Knowledge of the microclimate can give important clues for changing the prevailing climate in a favorable way. An illustration is the microclimate produced by screening with tall evergreens that provide a windbreak or shade. Another is the difference in an environment on the south side of a building versus the north side. Lastly, the influence of planting next to a heated basement versus an isolated planting bed can affect the flowering date. Plants can alter the form of the surface, increase the area for radiation and transpiration, shade the ground, change air movements, and trap air. All these factors cause a cooler, more humid, and stable microclimate. Gardeners and landscapers must consider these subtle changes when they select bulbs for specific locations. This is particularly critical for many bulbs that must be kept moist and thus should not be exposed to long periods of direct sunlight.
The design effect to be created requires careful consideration when making bulb selections. This includes factors such as:
Generally, there are several uses for summer and fall flowering bulbs in gardens and landscapes and most are suitable for two or more. Some terms used are described below:
Bed - A large or small cultivated area constructed solely for the purpose
of growing ornamental flowers and/or plants, including bulbs. Plants of a given
cultivar are generally closely spaced in
Border - A small strip of land in the foreground of an area in which
ornamental flowers and/or plants are planted or a wide strip which contains
flower bulbs, herbaceous perennials, annuals,
ornamental grasses, and woody plants and is called a "Mixed Border".
Cut Flowers - Plants that provide floral spikes suitable for use as either fresh cut or dried flowers.
Exhibition Bulbs - Species and/or cultivars which produce large, majestic flowers and which do well either singly or in small group plantings.
Ground Covers - Species which can be readily perennialized in combination with low growing evergreen plants, e.g., English ivy, Blue Rug juniper.
Lawns - Species which can be perennialized in lawns (usually selected from the VE and E flowering periods) and which flower well before the grass requires regular cutting.
Meadows - An area of grassland in which flowers are allowed to naturalize.
Rock Garden - An area where plants are cultivated with rocks. Plants must be adapted to terrain with shallow pockets of soil, extreme temperature fluctuations and water channeling.
Woodland Gardens - Areas in which species can be planted on the border of or amongst shrubs and trees. They normally flower early in the season (flowering periods VE and E) before shrubs flower and deciduous trees leaf out.
When flower bulbs are used in perennial locations, there are several ways to camouflage or reduce the negative impact of senescing bulb foliage. These include:
Many of the bulbs in Table 2 can be used as container plants for patios, balconies and/or as interior house plants. They are designated by the symbol (C). Some are used as hanging baskets (Achimenes), while others are used in large pots (Clivia) or flower boxes (Tuberous Hybrid Begonias).