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San Joaquin UC Master Gardeners
Smart Gardening Conference
September 29, 2012
“A fertilizer is any material containing at
least one of the essential elements for plant
growth that is added to the soil for the
purpose of supplementing the plant nutrient
supply.”
Sixteen elements are required for plant
growth.
Carbon, hydrogen and oxygen
Macronutrients: nitrogen, phosphorus,
potassium, calcium, sulfur, magnesium
Micronutrients: manganese, zinc, boron,
copper, iron, molybdenum, and chlorine
Nitrogen: Encourages healthy vegetative,
green growth
Phosphorous: Phosphorous contributes to
many fundamental plant processes such as
strong roots and setting flower buds
Potassium: Potassium (aka Potash)
contributes to the overall health and vigor of
plants. Helps the plant through stressed
times such as disease/insect damage,
drought and cold temperatures
Numbers represent the percentage of
nutrient compared to filler ingredients. A 10-
10-10 fertilizer contains 10% of each
nutrient.
A 10 pound bag of fertilizer labeled 5-10-5,
would contain 5% nitrogen, 10% phosphorus
and 5% potassium. The remaining 80% could
be comprised of other nutrients and filler.
50-lb bag of 10-10-10 fertilizer
Multiply 50 by 0.10.
Do the same for calculating the amounts of
phosphate and potash.
A 50-lb bag of 10-10-10 contains a total of 15 lbs
of nutrients: 5 lbs nitrogen, 5 lbs phosphate and
5 lbs potash. The remaining weight is filler,
usually sand or granular limestone. Another
example:
Multiply 50 by .08, which equals 4.
To calculate the pounds of phosphate: There
is no phosphate in this bag of fertilizer.
To calculate the pounds of potash: Multiply
50 by .24, which equals 12.
A 50 pound bag of 8-0-24 fertilizer contains a
total of 16 lbs of nutrients: 4 lbs nitrogen, 0
lbs phosphate, and 12 lbs potash. This would
leave us with 34 lbs of filler.
Fertilizer Lingo
Complete Fertilizers: Fertilizers that
contain all three major nutrients are
considered complete fertilizers. (10-10-10)
Incomplete Fertilizer: Lack one or more
major nutrients such as a fertilizer labeled 0-
20-20
Contain either equal amounts of each major
nutrient (N-P-K ratio 12-12-12) or a slightly
higher percentage of nitrogen than of
phosphorus and potassium (such as a 12-8-6
product).
Are intended
to meet most plants' general
requirements throughout
the growing season.
Are formulated for specific needs.
They're aimed at the gardener who wants a
particular combination of nitrogen,
phosphorus, and potassium for certain plants
or garden situations.
These feature the N-P-K ratios determined to elicit the best performance from the particular plant, as well as other elements proven valuable to that plant. Examples would be
citrus trees and acid-loving plants such as camellia and rhododendron.
These products are derived from the chemical sources listed on the product label.
Faster acting than organic kinds and provide nutrients to plants quickly, making them a good choice for aiding plants in severe distress from nutrient deficiencies.
Typically cheaper than organic
Derived from the remains of living organisms; blood meal, bone meal, cottonseed meal, and fish emulsion are just a few of the many available types.
Organic fertilizers release their nutrients slowly: rather than dissolving in water, they're broken down by bacteria in the soil, providing nutrients as they decompose.
Since plants can take up nutrients
continuously, it may be beneficial to provide
them with a somewhat steady supply
throughout their most active periods of
growth.
Slow-release fertilizers contain one or more
essential nutrients.
These elements are released or made
available for plant use over an extended
time period.
Liquid fertilizers are water-soluble powders or liquid concentrates that mix with water to make a fertilizer solution.
The liquid nutrients generally last 1 to 2 weeks, so you need to reapply often.
They are quickly absorbed, so plants get their benefits soon after you apply them.
They are great as a starter solution and for a quick boost during the growing season.
When properly diluted you also negate the chances of fertilizer burn.
Properly diluted liquid fertilizer is ideal for use of soft, sensitive and young plants.
Granular fertilizers are meant to be worked
into the soil or sprinkled around plants.
They last 1 to 9 months, depending on the
type
After application these types
of fertilizer should be watered
in immediately to avoid the
plants burning
Manures can be used to increase soil fertility.
When manure is spread in the spring, even if aged, it is safest to wait for at least one month before planting crops.
When composted manure is spread directly over the soil, it is helpful to add about 40 lbs. per 100 square feet, turned into the top 6 to 9 inches.
“Fresh” manure also can damage plant tissue and kill seedlings. It is too “hot” make sure you use manure that has been processed or composted.
It is not recommended that homeowners use
any manure from dogs, cats, or other meat-
eating animals, since there is risk of
parasites or disease organisms that can be
transmitted to humans.
Compost feeds the soil and fertilizer feeds
the plants.
Compost and organic fertilizers can work
together.
The organic matter in compost sponges up
the fertilizer nutrients until they are needed
by plants.
Compost also provides many nutrients that
plants need in small amounts, such as boron.
Primarily need nitrogen but many crops also benefit from some complete fertilizer (5-10-5, 5-10-10, 8-16-16, and 12-12-12).
Apply these fertilizers at rates of 1 - 2 pounds per 100 feet of row.
Consider light but frequent applications of nitrogen fertilizer every 3 to 4 weeks.
Avoid letting the fertilizer come into contact with the plant stems to avoid burning.
Not using compost or manure? Apply fertilizer that contains both nitrogen and phosphorus before planting.
Young fruit and nut trees in the pre-bearing
years (the first 2 -3 years) can use more nitrogen
per canopy area than mature, fully-bearing trees
Wait until early summer when there is 6 to 8
inches of new growth.
Apply about 2 oz of a nitrogen fertilizer, such as
ammonium sulfate (21-0-0), or 16-16-16 or 1 oz
of urea (46-0-0) or 2 pounds of compost once a
month until leaf fall.
Scatter the fertilizer on the soil under the tree,
keeping it at least one foot from the trunk and
water it in
Different varieties have
different needs
Fully-bearing, average-sized
mature trees in the home
orchard should be fertilized
at the rates stated in
Calendar of Backyard
Gardening Operations for Selected
Temperate Fruit and Nut Trees.
(This handout can be found at the fruit tree display)
Use a fertilizer labeled for citrus
Most mature citrus require
regular fertilization with nitrogen.
Nitrogen should be applied in January or February
just prior to bloom. The second application then
can be applied in May and perhaps a third in June.
Avoid late-season fertilization as it may affect
fruit quality, delay fruit coloring, and make the
rind rough.
Water the tree the day before, broadcast the
fertilizer over the root zone and water in well.
Withhold fertilizer from fall through midwinter.
Acid-loving plants thrive in a pH range of 4.5
to 6.5.
Azaleas, Rhododendrons, Gardenias
A complete fertilizer designed for acid-loving
plants
Fertilize during the growing
season, not the dormant
Add the following to the soil:
For hydrangea blooms to be blue- lower pH
A fertilizer low in phosphorus and high in
potassium is helpful in producing a good blue
color-25/5/30
A solution of 1 Tbsp aluminum sulfate per gallon
of water be applied to plants (which are at least
2-3 years old) throughout the growing season
For hydrangea blooms to be pink – raise pH
Add dolomitic lime several times a year
Use a fertilizer with high levels of phosphorus.
Do not fertilize at planting time.
Four weeks after planting, use a 10-10-10
fertilizer that contains ammonium sulfate or
a potassium sulfate.
Sprinkle 1 ½ tbsp within 12-18 inches of each
plant, but not directly on the crown or stems. Or
use organic-based fertilizers such as blood,
feather, or fish meal at the
rate of 1 pound per plant.
For flowering annuals, use an all-purpose plant food, such as a 5-10-5 or 10-10-10 formula.
Flowering plants have a special need of phosphorous and potassium to reach their blooming potential. Phosphorus will
encourage big healthy blooms
Foliage plants will flourish with a formula higher in nitrogen
Trees, shrubs, & vine apply 0.2 lb N in a 3 ft
x 3 ft area around base of plant immediately
after planting, again 6–8 weeks after
planting, and the following spring
Fertilizer should be applied at the “drip line”
of trees and shrubs and not directly on the
trunk or crowns.
Newly planted groundcover: 1–2 lb N per
1,000 sq ft immediately after planting and
again 6–8 weeks after planting
Usually when fertilizer is needed, only
nitrogen is necessary. Apply fertilizer to the
soil surface for these plants.
Broadcast about 1 to 3 pounds of actual nitrogen
per 1,000 square feet of planted area for shrubs
or per 6 inches of trunk diameter for trees.
With few exceptions, trees do not respond to
supplemental fertilization in California.
In fact, fertilizing healthy woody plants can be
harmful by encouraging excessively vigorous
growth.
Nitrogen and iron are the only nutrients in which woody plants are commonly deficient
Fertilize only as needed and only if other problems have been eliminated as the cause of poor growth.
Avoid overfertilization, especially with high nitrogen fertilizers. Overfertilization promotes excessive foliage that
may increase populations of pests such as mites, aphids, and psyllids. Excessive growth may cause bark to crack, allowing entry of fungi. Excessive fertilizer may also kill roots and burn or kill foliage.
Roses in general are heavy feeders. Roses
love being fed, and will reward you with
more blooms if they are fertilized
Stop fertilizing about
6 weeks before the
first frost date
How often to apply is a subjective decision,
based on the amount of time and devotion
you have.
What type of rose grower are you?
You like to look at roses from your window, but don't know the varietal names and only cut a few for the house.
Use a granular food with of about 10-10-10, applied every four weeks according to directions.
Fish emulsion applied as a liquid fertilizer when buds are about pea-size (about three weeks before each bloom cycle) will enhance bloom color.
Add chelated iron for rich green foliage.
During June, July and August, reduce the amount of fertilizer applied by half during but stay on the same 4-week frequency.
Realizing roses require a steady source of
food, and having the time to supply it, you
are willing to adopt a bi-weekly fertilizer
program for the big blooms.
Start with an application of granular food as
first growth appears in Spring.
Then begin a program of liquid fertilizers
every 2 weeks
Add Epsom Salts at 1/4 C per bush, either
dissolved in the liquid feeding or sprinkled
straight from the package onto the soil
Your "main line" is your hose, and you have
had it surgically attached to your hand, since
you fertilize weekly.
Your main goal is a trophy in a local, district
or national rose show.
Use the previous mentioned rotation of
fertilizers on a weekly basis, but reduce the
concentration to about half of that called for
on the label.
The majority of house plant fertilizers are
about 20-20-20
Frequency of fertilizer application varies
somewhat with the vigor and age of each
plant.
Houseplants should only be
fertilized during periods of active
growth.
Plants in low light will not need
as much fertilizer. Brighter light
will need more
A general guideline to use is to fertilize
monthly in the spring and summer and only
two or three times in the fall and winter.
Never fertilize when the soil is dry.
Pots should be leached every 4 to 6 months.
Leaching is accomplished by pouring an amount
of water equal to twice the volume of the pot on
the soil and letting it drain completely.
This will flush out salts left behind by fertilizers
So many plants to fertilize so little
time to cover them all!
We’re here to teach you where to find the
answers!
Start by clicking
here
You will see the
following list
Click on fruit
trees and you
will get this list
Along with other helpful
information for growing
avocados including planting,
harvesting and pests you
will get specifics on
fertilizing
Why there is no magic number for turf There are so many different
types of turf grown in our county (Cool Season vs. Warm Season grass)
Size of lawn
Temperature
Soil types
Recommend using IPM site Identify turfgrass species if you don’t know what
you have
Will calculate how much to apply by entering species and area of lawn
Map of entire
state
Red Fescue
Don’t Know?? That’s ok! Use the turf key
Nitrogen is the only nutrient that turf grass
needs on a regular basis.
In general, lawns should be fertilized about
4 times a year with 1 lb. of nitrogen at
each application
Both cool-season and warm-season grasses
require 4 - 6 lbs. of actual nitrogen per year.
This amount is usually divided into 4 applications
of 0.5 to 1 lb. of actual nitrogen per 1000 sq. ft.
per application.
Grasscycling supplies about 20% of the
fertilizer requirements of most grasses.
Leaving your clippings on the grass after
mowing is beneficial as it returns nutrients
back to the soil.
It is only beneficial if you follow proper
watering, mowing, and fertilizing guidelines.
Not this
Nitrogen: Older leaves, needles are yellowish; new growth sparse, undersized; plants grow slowly and may drop foliage prematurely.
Iron: New foliage small and yellowish, except green along veins; dead spots may develop between veins; leaves drop and dry prematurely.
Zinc: Leaves yellowish; new growth may be delayed; new leaves may be small, narrow; foliage may be purplish.
Phosphorus: Foliage dark green, bluish, or may develop spots; shoots short and spindly; slow growth.
Potassium: Foliage growth is sparse; older foliage is yellowish and may have brown tips and margins near leaf edge or between veins.
Follow the directions on the package for how
much to use and how often to apply it.
Overfertilizing is worse for plants than
feeding them too little.
Too much fertilizer causes rapid, weak
growth that is susceptible to damage by
pests and diseases, and excess fertilizer runs
off and may find its way into the water
table, causing pollution.
More is not better!
Questions?
Citrus
http://homeorchard.ucdavis.edu/files/140618.pdf
Fruit trees: http://homeorchard.ucdavis.edu/calendar.pdf
http://hoorchard.ucdavis.edu/fertilizing2.pdf
blue berries: http://ucanr.org/sites/gardenweb/Berries/?uid=25&ds=466
landscape trees: http://anrcatalog.ucdavis.edu/pdf/8045.pdf
Lawns
http://www.ipm.ucdavis.edu/TOOLS/TURF/MAINTAIN/fertwhen.html
http://www.ipm.ucdavis.edu/QT/lawnfertilizingcard.html
http://www.ipm.ucdavis.edu/TOOLS/TURF/MAINTAIN/ferthow.html
sunset crash course: http://www.sunset.com/garden/garden-basics/crash-course-fertilizers-
00400000015144/
woody plants" http://www.ipm.ucdavis.edu/PMG/GARDEN/ENVIRON/fertilwood.html
Reading bag: http://www.calfertilizer.org/Fertilizer%20Facts.pdf
woody plants: http://ucanr.org/sites/UrbanHort/files/80113.pdf
types of fertilizer: http://flowers.about.com/od/Flower-Gardening/a/Choose-The-Right-Flower-
Fertilizer-Type.htm
reading bag: http://gardening.about.com/od/gardenprimer/ht/fertilizerlabel.htm
Houseplants: http://www.ces.ncsu.edu/depts/hort/consumer/quickref/houseplants/fertilizing.html
roses: http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7465.html#CULTURAL
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