A number of planting techniques can be used for flower bulbs.
- Laying out the bulbs
For a beautiful display in parks and planting beds, it is important to lay out the bulbs evenly over the location being planted. It would be advisable to start by laying out the bulbs at the proper distance apart. This prevents surprises when coming to the end of the planting bed!
Before the bulbs are laid out, the soil should be thoroughly loosened to a depth of 25 cm. (10 inches) Next, the bulbs can simply be planted, after which they will produce good roots.
- Planting can then be done with a trowel, one by one. A single person (planter) can plant 600 to 700 bulbs/hour depending on his/her experience and the kind of bulb.
- Another method uses raised planting beds. After laying out the flower bulbs, they are covered with a layer of soil 10 to 15 cm (4 to 6 inches) thick. This method is used more frequently when the planting is intended for a one-year display.
After planting, the planted areas should be evenly raked. To keep the soil from drying out, freezing or panning, it would be advisable to mulch the area with 2-3 cm (1 inch). of organic material (peat litter/compost).
- Scattering the bulbs
Bulbs can also be scattered into a border or naturalising zone to provide a more natural look. The bulbs are then planted wherever they land. Here again, planting is easier if the soil as been loosened before planting. The number of bulbs that can be planted per hour will be much lower because the existing planting will have to be considered.
- Bulbs in the grass
When bulbs are being planted over a small area in the grass, a piece of sod can simply be lifted for planting each group of bulbs. After making sure that each bulb has been placed upright in its planting hole, the sod can be replaced. Once the sod has been tamped down, the planting location will be invisible after a few days.
- Planting by machine
Because labour costs are the biggest expense involved in planting flower bulbs, a special machine can be used that will save 90% of these costs. This machine lifts the sod up and scatters the bulbs into a planting trench. The machine can plant around 10,000 narcissi (daffodils) and 25,000 crocuses or other small bulbs per hour. In this method, the flower bulbs are planted in rows; this makes it a perfect method for planting verges. This method does not lend itself for planting round patterns. It is a fast planting method that greatly reduces labour costs.
- Layered (lasagna) method
To ensure a longer flowering period when using flower bulbs, choose kinds with consecutive flowering periods and plant them at the same site. By planting them at different depths, they can be planted at practically the same spot. This method is most commonly used in spring-flowering beds that have to remain attractive throughout a single season.
In general, the flower bulbs that will bloom last are planted at the deepest level. The earliest to bloom in the spring will be planted closest to the surface. This technique is also referred to as the “lasagna technique” and can be applied to planting bulbs in the ground as well as in pots and containers.
It is important to plant flower bulbs at the right time. Flower bulbs that bloom early (from January to March) should be planted in September/October. The best time to plant the ones that bloom later (March-May) is October/November.
A general rule for the planting depth is to plant the bulbs at a depth at least twice the height of the bulb (a minimum of 5 cm / 2 inches). Not planting bulbs deep enough results in poor rooting that leads, in turn, to an uneven emergence of short spindly plants. Planting too deep can result in rotting as well as late emergence.
A good crop rotation plan that keeps flower bulbs from being planted no more often than once every four years in the same place will limit the need to apply soil disinfection agents.
Sometimes, however, a flower bulb planting site is so important for the image of a garden, park or city, that the same location is used every year. In this case, it will be highly probable that soil diseases such as Rhizoctonia tuliparum will become a problem. Many flower bulbs such as tulips, hyacinths and lilies are susceptible to this disease, but other perennial plants can be harmed as well.
If it is highly probable that Rhizoctonia will be found in the soil, it is possible to work tolchlosfos-methyl (0.5 litre/200 litres of water or 0.11 gallon/44 gallon of water) through the soil with a rotary cultivator previous to planting.
The soil will have to be loosened prior to planting. If the soil has a low pH, it would be advisable to lime it immediately before planting; if the pH is too high, it can be reduced by adding peat litter to the soil.
Improving the soil and increasing its organic level can be accomplished by adding organic fertilisers such as compost and manure.
Manure contains somewhat more nutrients than compost, and, like compost, it maintains soil structure and the biodiversity of the soil. Manure is available in fresh, granulate and powder forms. Packaged manure is usually cow manure, but chicken manure is sometimes added. The packaging indicates how much manure to use.
Fresh manure does not release its nutrients immediately but needs some time to decompose. The use of stable manure at least one year old is preferable; fresh cow manure contains ammonia that can “burn” the leaves of plants.
When planting in clay soil, it is best to apply manure in the autumn; in gardens with sandy soil, an application in early spring (March) is best. Fresh manure should be spaded under shallowly (not more than 10 to 15 cm. /4-5 inches deep).
Manure is a very good choice for applying to new planting sites.
Compost is the best choice for both fertilizing and improving the soil. It introduces nutrients into the soil, improves soil structure, and maintains a healthy biodiversity in the soil. This gives plants more resistance to harmful bacteria and fungi.
Compost makes sandy soil easier to work and more water-retentive. Soil with a high clay content is made easier to work and more air-permeable when one part compost and one part sand are worked into it. Actually, compost is a better soil-improving agent than manure. It ensures a balanced development of bacterial organisms in the soil.
Too much compost is not beneficial; an exceedingly high concentration of compost near the roots could possibly burn them. A thin layer of compost can be applied to borders and lawns once a year in March or April (or in the autumn for heavy clay soils).
Courtesy of the International Flower Bulb Center (www.bulb.com)