Resource Book on Horticulture Nursery Management

There are four main nutrients that are most likely to be a problem in the soil:
nitrogen, phosphorus, potassium, and calcium. The first three nutrients are found in most
mixed fertilizers, and calcium can be applied separately.
� Nitrogen is necessary for new cell formation in all parts of a plant. Compared to
other nutrients, nitrogen is typically the most lacking. A symptom of a shortage
of nitrogen is yellow-green stunted growth.
� Phosphorus is necessary for development of roots and stems. This nutrient also
stimulates fruit and seed production. A symptom of Phosphorus deficiency is red
or purple discoloration of leaves. Because phosphorus gets fixed to soil particles,
it is important to place it close to the roots.
� Potassium (potash) is necessary for strong roots, stem development and deep
flower color. A symptom of potash deficiency is weak stems and yellowing or
browning leaf tips and edges.
Fertilizer should be water soluble to be available to the plant soon after application.
The organic nutrient sources such as compost, manure, bone meal, and blood meal are
not readily available to plants. These materials must be broken-down before they are
available to the plants. This makes them slow acting fertilizers. The nutrients of
inorganic plant foods are in soluble form, which are readily available to plants. Inorganic
plant feeds are not long lasting; therefore, frequent fertilizing may cause the chemicals to
destroy the plant. If applied direct contact with foliage and roots must be avoided as it
may damage or even kill the plant.
The percentage of nutrients is indicated on the fertilizer container. An inorganic
fertilizer labeled as 20-20-20 indicates equal portions of nitrogen, phosphorus and potash
and typically used in gardens with little nutrient deficiencies. Due to the difference
between organic and inorganic plant feeds, a combination of the two may produce the
best results.
� Liquid or water soluble fertilizers are good for accurate applications for
container plants.
� Slow release fertilizers feed plants for an extended period of time, which is good
for lawns and perennial plants.
� Limestone (calcium) neutralizes the acid level in soil.
� Side dressing adds fertilizer to plants during the growing period. Apply the
fertilizer on top of the soil at least six inches away from the stem of the plant.
� Base feeding is especially good for shrubs and roses. Apply fertilizer on top of
the soil at least six inches from the base of the plant and extend to approximately
twelve inches beyond the branch tips. Scratch the fertilizer into the soil without
disturbing the roots.
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