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Gardening Answers Knowledgebase

Search Results for ' Fertilizers'

PAL Questions: 11 - Garden Tools: 2 - Recommended Websites: 1

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Keywords: Geranium, Fertilizers

PAL Question:

What would be the best fertilizer for hardy geraniums and when?

View Answer:

Established hardy geraniums do not need much more than an application of compost in spring. Most commerical fertilizers will provide too much nitrogen, causing weak growth that flops over or needs staking. (Source: The Gardener's Guide to Growing Hardy Geraniums, by Trevor Bath, 1994)

Season All Season
Date 2006-02-26
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Keywords: Hydrangea, Fertilizers

PAL Question:

I have a few Hydrangeas that have not been doing their best. I think I have the exposure down, and their colors. I need advice on what fertilizer is best for them and when, how much and how often to apply it. I try to stay as organic as possible.

View Answer:

According to Hydrangeas: A Gardeners' Guide by Toni Lawson-Hall and Brian Rothera (Timber Press, 1995), hydrangeas do not generally require special feeding. If you wish, you can apply a general fertilizer twice a year. "As important as feeding, and in fact another method of supplying nutrients, is mulching." The authors suggest using mature compost or leaf-mould. Mulching in the spring to a depth of about 3 inches will help protect the roots of your hydrangeas from drying out (but never put mulch directly up against the base of your shrubs). Mulching also suppresses weeds. Since you garden organically, mulch may be your best bet for supplying a slow and gentle dose of nutrients. If the plants continue to fare poorly, you may want to do a soil test to see if there is some kind of nutrient imbalance that needs correcting.

Season All Season
Date 2006-10-26
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Keywords: Rosaceae (Rose Family), Rhododendron, Fertilizers

PAL Question:

Is it okay to fertilize my rhodies, azaleas, and roses in September? I missed doing it in August.

View Answer:

Generally speaking, it is best not to fertilize your shrubs after mid-summer. The tender new growth that results is susceptible to frost, disease, and insects just at the time of year when the plant is beginning to shut down. This is also true of roses, which are even more tender and susceptible than rhododendrons and azaleas.

An article by Terri Richmond (British Columbia) on the American Rhododendron Society website, entitled Fertilizing Rhododendrons the Organic Way supports the practice of fertilizing in spring. (Keep in mind that azaleas are in the same genus as rhododendrons.)

Oregon State University Extension suggests that budbreak in spring is a good time to fertilize roses, just as new growth is beginning. Stop fertilizing in late summer. Oregon State University also weighs in on fertilizing rhododendrons (if needed,in spring shortly after flowering, and preferably with organic fertilizer).

Season All Season
Date 2007-09-07
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Keywords: Fertilizers

PAL Question:

I have heard that hair used in a garden is good for pesticide and fertilizer. Do you have any information about this? Also does it have to be human hair or is dog hair considered to be the same?

View Answer:

Here is what The Rodale Book of Composting (Rodale Press, 1992) says about using hair as fertilizer. "Between 6 and 7 pounds of hair contain as much nitrogen as 100 to 200 pounds of manure. Like feathers, hair will decompose rapidly in a compost pile but only if well-moistened and thoroughly mixed with an aerating material. Hair tends to pack down and shed water, so chopping or turning the pile regularly will hasten decay."

I would think that any hair, including dog, would respond similarly. I would not add the hair directly to any planting area without putting it through the composting process described above. Also, hair which is heavily processed with chemicals (perms, dyed hair, etc.) doesn't seem like anything I would want to add to the garden.

I could not find anything in the literature which mentions the use of hair as a pesticide, although I have heard that hair strewn around the garden beds may discourage animals from foraging there.

Season All Season
Date 2008-02-28
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Keywords: Schlumbergera, Rubus, Indoor gardening, Insect pests, Fertilizers

PAL Question:

I have whiteflies on my orchid Christmas Cactus. How can I get rid of them? I also would like to know if grass clippings are good to fertilize raspberries.

View Answer:

Christmas cactus, or Schlumbergera bridgesii, does occasionally have problems with insects. Whitefly nymphs and adults cause damage by sucking plant juices, and their feeding can weaken a plant. They also secrete a sticky substance called honeydew, which may then harbor sooty mold. For indoor plants affected by this insect, you might try gently washing the leaves. Rodale's Encyclopedia of Indoor Gardening, edited by Anne Halpin (1980) says that adults are easy to wipe up when it is colder indoors, and the young are usually on the undersides of leaves and may be wiped off with a sponge. Many whiteflies are now resistant to insecticides, and so it is best to start with plain water or soap and water. The book Indoor Gardening the Organic Way by Julie Bawden-Davis (Taylor, 2006) lists sticky traps, insecticidal soap, alcohol spray, oils, and pyrethrin as potential controls. There are products containing Neem oil which could help, if plain water or soapy water don't control the problem.
Clemson University Extension has some helpful information on general care of this plant.

As for using grass clippings as fertilizer, as long as the grass was not treated with weed-and-feed or other pesticides, it should be a good source of nutrients. Also, avoid using grass which has already gone to seed. Mulch It! by Stu Campbell (Storey Books, 2001) advises not to spread the clippings too thickly, and to let them dry out a bit before using. Here is a link to Virginia Cooperative Extension's page on recycling grass clippings.

Taylor's Guide to Fruits and Berries edited by Roger Holmes (Taylor, 1996) says that "reasonably good soil enriched with an inch or two of good compost or a moderate dose of balanced fertilizer each year should provide sufficient nutrients for your plants to thrive. Berry lovers sometimes provide regular doses of foliar fertilizers to give their plants a boost. Absorbed by the leaves in liquid form, seaweed, fish emulsion, and similar organic materials in balanced formulations provide a broad spectrum of nutrients."

Season All Season
Date 2008-05-24
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Keywords: Tulipa, Fertilizers

PAL Question:

I have planted petunias over tulip bulbs. Is that o.k., and also, how and when can I fertilize tulips this fall?

View Answer:

Your idea of planting a later blooming plant over the tulips is just fine. It will conceal the dying foliage nicely. According to The Plant Care Manual by Stefan Buczacki (Crown,1993), the time to fertilize tulips--if you need to fertilize them at all--is early spring. They can be mulched (with compost, for example) in early fall and spring, and given liquid feed 2-3 times after blooming and while still in full leaf.

The Brooklyn Botanic Garden's Spring-Blooming Bulbs (2002) gives the following general advice:
"Most bulbs do better with regular fertilizing, and bulb fertilizer is one good choice. Some gardeners prefer to use bone meal (though the way it is processed today saps most of its nutrients) or rock phosphate. Even better is a healthy dose of compost--in fact, if you regularly improve the overall quality of your soil with compost and other organic amendments, you don't have to provide much fertilizer for most bulbs. Mix compost or fertilizer into the soil when you're planting or top-dress, following label directions. to help boost the bulbs for next year's bloom, you can also top-dress the soil in spring after blooming. Remember to work any fertilizers well into the soil, and avoid high-nitrogen fertilizers (like lawn fertilizer)."

You may not need to fertilize your tulips if they are the showy varieties (the ones that don't come back year after year in the garden). Seattle-area gardening expert Ciscoe Morris says the following:
"Don't fertilize spring-blooming bulbs if you're going to replace them next fall. Most books recommend adding bone meal and fertilizer whenever you plant spring-blooming bulbs. That's only necessary if the bulbs you're planting are the kind that tend to naturalize and return to bloom every spring for years to come. Those bulbs not only need fertilizing at planting time, but also should be fed every spring thereafter. On the other hand, most of the big, showy tulips are ill-suited for our rainy cold winters and rarely perform well the second year. If, like most of us, you treat them as annuals and replace the bulbs every year, don't waste time and money fertilizing them. These bulbs already contain everything they need to grow and bloom, and as long as the bulbs don't rot as the result of poor drainage, and nothing eats them, they'll put on a great display without the addition of nutrients."

Season All Season
Date 2010-09-24
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Keywords: Vaccinium, Organic fertilizers, Fertilizers

PAL Question:

Is ammonium sulfate considered an organic fertilizer? I'd like to use some on my blueberries, but suspect it is not organic.

View Answer:

According to Fertilizers and Soil Amendments by Roy Hunter Follett (and others), ammonium sulfate is one of the oldest chemical fertilizers, and is "a frequent by-product of the steel industry, particularly the coking of coal." That doesn't sound like it meets organic guidelines. It is also tricky to use because it can cause phosphorus and aluminum to build up in the soil. The Organic Materials Review Institute lists it as a prohibited (for certified organic growers) synthetic crop fertilizer and soil amendment. You might do better using a slow-release certified organic fertilizer labeled for acid-loving plants. Cornell University Extension's publication, 2013 Production Guide for Organic Blueberries" mentions fish, soy, and alfalfa meal as organic-acceptable amendments.

Season All Season
Date 2011-04-01
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Keywords: polymer-coated fertilizer, Fertilizers

PAL Question:

Can you tell me what is in Osmocote? Every time I buy plants at nurseries and sales, the containers are full of these little round fertilizer pellets that get into my garden soil and never seem to decompose. Also, I try to grow organically, and I suspect this stuff is synthetic.

View Answer:

There are various formulations of Osmocote, marketed by the Scotts Company as "plant food." You can look up the Material Safety Data Sheets for each of them. I looked at the MSDS for Osmocote Plus, and nothing on the product label suggests that this is a certified organic product. It contains nitrogen, phosphate, soluble potash, and various minerals. The "sources" are coated in polymer. According to this article on "PCFs" (polymer-coated fertilizers) by Douglass Jacobs, published in the 2005 USDA Forest Service Proceedings, the type of polymer material in fertilizers (such as Osmocote) varies and the degree to which the fertilizer is released will vary accordingly. Here is an excerpt:
"The coating technology in OsmocoteŽ (OM Scotts Company, Marysville, OH) was developed in the 1960s, and this coating is classified as a polymeric resin. The coating process involves coating a soluble fertilizer core with a thermoset copolymer of dicyclopentadiene and a glycerol ester (linseed oil) dissolved in an aliphatic hydrocarbon solvent."

I am not a chemist but if I feel I ought to be in order to understand what the polymer coating consists of, chances are good that it is not something one would want in an organic garden. Although it is written by a local gardener and not a scientist, you may find this article about polymers from Paghat's Garden of interest. For a scientific approach, see horticulture professor Linda Chalker-Scott's article on polymers (albeit in hydrogels, not fertilizers). I discovered one polymer product (a seed coating) in the lists of the Organic Materials Review Institute which is certified for use in organic gardens. However, I was not able to find out anything about the composition of the polymer material. Seed treatment products which are "allowed" by OMRI are non-synthetic. Synthetic products are not allowed. OMRI's statement on what is restricted "includes all synthetic pesticides and any synthetic materials not explicitly listed, plastic polymer pelletization [...]."

If you can bare-root most of your plant purchases and dispose of the polymer pellets in the trash, you may be able to avoid introducing them into your landscape. I also suggest talking to your favorite nurseries and asking them to seek more environmentally friendly alternatives.

Season All Season
Date 2011-05-12
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Keywords: Philadelphus, Failure to flower, Pruning shrubs, Fertilizers

PAL Question:

I just bought a house with a garden which has good bones, but has been untended for a long time. I believe the garden has 4 Philadelphus X virginalis 'Minnesota Snowflake' plants. They are deciduous in the winter, and they have greened up nicely in the summer. They are about 6 feet tall. On the 4 plants, this first summer, I've only seen 2 flowers. Can these shrubs be salvaged by using a blooming (high in phosphorus) fertilizer? Or do they need something else?

View Answer:

The three things I would ask about Philadelphus with few flowers:

  • Are they in full sun? (Sun is needed for best flowering results.)
  • Have they been pruned and, if so, when? (Pruning is best done in late summer, after flowering.)
  • Are they growing near a lawn or other area which receives fertilizer that is higher in Nitrogen (N) than Phosphorus (P) or Potassium (K)?

I would recommend that you test the soil before embarking on a plan of fertilization, unless you are adding a mulch such as compost, which releases its nutrients slowly. Philadelphus is usually considered a light feeder (i.e., it doesn't require a lot of supplemental fertilizer).

As far as a future pruning regime for the shrubs, Jacqueline Heriteau's Complete Trees, Shrubs & Hedges: Secrets for Selection and Care (2005) says that Philadelphus "blooms on the previous year's growth. A light annual pruning of older branches right after flowering keeps mock orange shapely and productive. Branches more than five years old should be removed in winter or early spring."

Season All Season
Date 2011-07-12
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Keywords: Prunus persica, Fertilizers

PAL Question:

We have a white peach tree that was just OK this year. I am wondering what I can do to get the most out of it next year - what is the best fertilizer for peaches?

View Answer:

According to Sunset's Western Garden Book of Edibles (2010), peach trees may be fertilized with a 10-10-10 complete fertilizer (the numbers correspond to N-P-K, nitrogen, phosphorus, potassium) at bud break in late March. "Give young trees 1/2 pound per year of age and give mature trees up to 5 pounds (for full-size, full-grown trees). Spread fertilizer evenly over the entire root zone."

Washington State University Extension has general information on fertilizing for home orchardists. Here is a relevant excerpt:

"Nitrogen is not needed in most of western Washington since we have such high levels of organic matter in our soil, and it is continually released during the summers. Nitrogen controls growth. With excess we get rank growth. Fruit maturity is delayed; and storage life of apples and pears is reduced. Peaches need more nitrogen so applications may be necessary."

Season All Season
Date 2011-10-06
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Keywords: Mulching, Fertilizers, Compost

PAL Question:

I have a large and never-fed garden. I wish to start feeding these plants. I'm composting now, but when and how often do I fertilize?

View Answer:

Has your garden been thriving in years past? If so, I don't think you need to add fertilizers. There's no single packaged fertilizer that will be universally beneficial to every plant in your garden. Different plants have different needs, and it's never wise to add fertilizer without doing a soil test.

On the other hand, you mention you are tending a compost pile. You can apply compost once or twice a year and it will be helpful to all your plants.

Here is information from The Ann Lovejoy Handbook of Northwest Gardening (Sasquatch Press, 2007):
"When do we need to feed? For ornamental plants, including trees and shrubs, spring and fall are the traditional feeding times. Spring feeds are generally fast-acting, offering rapidly growing plants the nutrients they need for a strong summer performance. A feeding mulch of compost can be fortified with fast-acting alfalfa, which will release more nitrogen if combined with composted manures. Alfalfa comes in meal or pellets. I like the big pellets used to feed goats, which are easy to spread and are available without added medication [my note: some alfalfa is treated, for use as animal feed].

"In fall, most plants stop producing fresh top growth, even though our Northwest winters are generally mild. Fall is a good time to feed roots, which continue to stretch and grow underground despite low temperatures. Adding whole fish meal to your compost feeding mulch will fortify roots with phosphorus."

Professor Sarah Reichard, director of UW Botanic Gardens, discusses fertilizers as sources of pollution in our water supply. In her book The Conscientious Gardener: Cultivating a Garden Ethic (University of California Press, 2011), she states:
"If water inevitably drains downhill, how do we stop fertilizers and pesticides from moving with it? The easiest way is not to use them. This needn't come at the cost of your plants. Most woody plants and herbaceous perennials do not require much fertilizer. Mulching with well-aged manure, compost, or other easily broken-down organic materials will supply all the necessary nutrients."

Season All Season
Date 2013-01-19
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Keywords: Organic fertilizers, Fertilizers

Garden Tool:

Gardeners with a wood burning stove or fire place often wonder whether they can use the ash as a source of potassium. The answer is yes if only wood (and no glossy paper) was burned. Where and how much? That depends. Wood ash raises soil pH, so if you have acid soil use it on the vegetable garden where a neutral pH is preferred, but avoid shrubs that like acid soil, such as Rhododendrons and Camellias. Recommended amounts vary, from a cupful around rose bushes to 20 pounds per 100 square feet for slightly acidic soil. Always work it into the soil. Read more about wood ashes from Oregon State Extension

Season: Winter
Date: 2007-03-26
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Keywords: Soil testing, Garden soils, Plant-soil relationships, Soil amendments, Fertilizers

Garden Tool:

Successful gardeners know that healthy soil translates to healthy plants. See the guide to soils and fertilizers for the home gardener from WSU Cooperative Extension.

Season: All Season
Date: 2007-07-12
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December 12 2014 11:33:49