Horticulture Principles and Practices

Disadvantages
1. Nursery care is an additional production activity that increases production costs.
Nursery care requires the provision of artificial sources of heat (in some cases),
light, and space.
2. Seedlings are not as readily amenable as seeds to mechanized planting.
Mechanized planters for seedlings have been developed for some crops, but
vegetative planting materials are more delicate than seeds. In some cases,
semimechanized planting operations, in which people feed seedlings into the
planter manually as the tractor moves along, are used.
3. Seedlings are bulky to handle. Seedlings are raised in containers that need to be
transported to the field.
4. Seedlings should be planted promptly. Seedlings must be transplanted before they
are too old. Seedlings may become too big for their containers and develop root
problems (pot-bound).
5. More immediate postplanting care is needed. Transplanting shock is a problem
when indirect seeding is used. If seedlings are not properly prepared for transplanting,
they will take a longer time to become established. Transplanting must be done at a
certain time of day and may require a starter application of fertilizer for good and
rapid establishment. Newly transplanted seedlings must be watered immediately and
more frequently until well established.
9.15 SEED NURSERY ACTIVITIES
When raising seedlings at home, a section of the garden may be reserved for this purpose.
A raised bed should have a very fine tilth. Seedlings may be grown in beds or in a
variety of containers as described in the following section. Seedlings may be raised
indoors in the basement of a home or some other convenient place. Special units may be
purchased for this purpose. These units vary in size, design, and versatility; some are
equipped to control temperature, humidity, and light.
9.15.1 CONTAINERS
Containers are discussed more fully in Chapter 11.
Flat
A shallow, rectangular
container used to start
seedlings.
Flats
A horticultural flat was originally a wooden box measuring, for example, 24 × 18 × 3
inches (61 × 45.7 × 7.6 centimeters) (L × W × H) (Figure 9–9). Plastic flats are more
durable and easier to manage and thus more popular today. Styrofoam flats are also
used. Provision must be made for drainage by either drilling holes in the bottom
boards or by leaving spaces between the pieces of wood. To prevent losing the soil
through the openings in the bottom of the box, a sheet of paper (e.g., newsprint) may
be used to line the bottom before filling with the appropriate mix of planting media.
The flat should be filled and leveled off to about 1 inch (2.54 centimeters) below the
top of the box.
304 Chapter 9 Sexual Propagation
Cavity Seeding Trays
Cavity seeding trays are plastic containers that may be obtained as individual cells
(cells vary in size) but often come in sets (2, 4, 6, and so on) (Figure 9–10). Each cell
has a drainage hole in the bottom. The advantage of this container system is that it
facilitates transplanting because the roots of individual plants are confined to a cell.
Commercial producers of bedding plants employ a large-scale mechanized system
called plug production, which entails the sowing of individual seeds into individual
plastic cells by specially designed machines. The sown seeds are automatically