I teach classes on fertilizing and fertilizers, so I tend to have some rather firm opinions :-) But they are pretty well supported by scientific evidence.

Do you use slow release fertilizer? I do when doing container planting :-) And when I do fertilize inground plantings, I use only organic fertilizers which are by nature slow release.

Do you like to spread an inch of compost or manure each spring? Yup! But it is generally several inches and I do it twice a season. I use compost as a mulch as well as to supply/replenish necessary nutrients. I've found that by routinely mulching with compost, you can eliminate or significantly reduce just about any other supplemental fertilizer applications.

How do you know when the ground is sufficiently warm to fertilize? That depends on what type of fertilizer you are using. Organically based fertilizers require the activities of soil organisms to make them available to plant roots and these guys do not become active until soil temps warm to at least 45F. Synthetic fertilizers are water soluble and technically could be applied at any time, however if the plants are in dormancy, they are unable to metabolize the nutrients and so the stuff is wasted.

Do you fertilize your pots the same way? No. Because container plantings do best in soils that have minimal organic matter (like compost), they tend not have very good populations of soil organisms present. No soil critters, no ability to convert oragnic ferts into a usable form. I include a CRF (slow release) fert when I pot them up and supplement that with a liquid fertilizer periodically through the growing season. Because all container plantings need frequent irrigation, nutrients tend to get leached out rapidly and these must be replaced for optimum growth - container plants generally get fertilized much more frequently than anything in the ground will require.

Do you typically use the same fertilizer on all of your perennials, shrubs, etc? No. When I do have a need for fertilizer other than just compost, I tend to use ones specifically formulated for that purpose. Often that is one for acid loving plants as sometimes soils that are not acidic enough tend to bind up or restrict nutrients these plants need. Even though my soil is slightly to moderately acidic, sometimes it needs help :-) And I tend to use a fertilizer that is higher in P and K for heavy 'feeders' like roses or clematis. When in doubt, a balanced (all three numbers the same), complete fertilizer is appropriate for virtually any type of plant.

Is there anything you choose not to fertilize (other than newly planted)? Other than mulching routinely with compost and any container plantings, I tend not to use much fertilizer at all. In cultivated gardens with normally amended soil and especially those that receive organic mulches, there is typically little need for fertilizers. Lawns are different as are edible crops or annuals that are harvested and removed, along with the nutrients they contain. One should always be conscious of what your plants are telling you in their appearance or the way they grow and provide nutrients as necessary but the advertising of the fert manufacturers like MiracleGro that imply you cannot possible have a 'good' garden without routine fertilizer applications is grossly overstated. Fertilizing when unnecessary can cause just as many problems as not fertilizing at all and is a huge contributor to pollution (synthetic ferts only).

What type of fertilizer do you like best? Other than container plantings, if I had to pick a fertilizer (not compost), it would be an organic product. There is minimal chance of 'burning', they are hard to overapply (although possible), they do not leach into groundwater and contribute to pollution and they stimulate soil biology. They most closely duplicate the way plants obtain nutrients in the wild :-)

Thank you for all of this information! So you put several inches of compost down each spring? Do you scratch it in?

You don't add any compost to container planting? I usually use potting mix but I mix in compost. Is that wrong?

Can you give some other examples of organic ferts besides compost? Thanks!

No, I use the compost only as a mulch :-) The only time it gets incorporated into the soil is if I am adding any new plantings or dividing/moving existing ones.

Container plantings require a very porous, well-aerated, well-draining soil. Adding compost to a container potting mix can create drainage problems, as the compost continues to breakdown. It compacts too rapidly and in doing so, you lose the spaces in between the soil particles - that reduces the amount of oxygen available to the plant roots and prevents water from draining freely. Ideal container mixes should have minimal amounts of organic material (peat, any kind of garden soil, compost, etc.) and heavier concentrations of high textured ingredients like bark fines, perlite, pumice, clay, granite grit, etc.

Organic ferts are typically derived only from plant or animal byproducts - alfalfa or cottonseed meal, bat guano, kelp or fish emulsion, blood or bone meal, etc. Mineral or rock powders often get grouped as organic as well, as they exist naturally in the environment. Most of these tend to feature one of the basic plant nutrients over the other two. A number of companies market preblended organic fertilizers that offer a more complete formulation of nutrients. Espoma is one brand that is pretty widely available throughout the east coast (it may not be 100% organic - check the individual lables) but there are others: Fox Farms, Dr. Earth, etc. Non-organic fertilizers, often referred to as synthetic fertilizers, are derived (synthesized) from byproducts of the petrochemical industry. Unless treated, they tend to be very fast acting, can burn plants if misapplied and because they are water soluble, have the potential to leach into groundwater. ALL fertilizers will have the NPK labelling on the packaging regardless of origin. Those that have only one number present (i.e., 0-45-0 aka triple phosphate) are generally considered soil amendments rather than fertilizers as they are only addressing a single soil issue.

The attached link has a pretty good explanation of various types of organic fertilizers, how they work and what nutrients they provide. These are individual or single ingedient fertilizers, not the preblended formulations I referred to above. The preblends would include a variety of these different products.

Here is a link that might be useful: organic fertilizers

I am bumping this post up to the top because it has so much excellent information in concise format. Thanks, gardengal, for taking the time. I hope every newbie reads this, and it's a mighty fine review for the rest of us.

perhaps i missed it..

but why do you think they need fert?????

any basic, decent soil should provide just about everything your plants needs.. with just a small application of compost ... as they say.. build the soil and the plants will follow

think of it this way .. they are not children ..

they do not need the diaper changed..

they do not need an education

and they really should NOT need to be fed ....

etc ...

unless you are in crop production ... annual feeding is not requisite ...

if and when you see some decline in size or vigor.. a little of this or that might be helpful ...

but it just isnt something that MUST be done ... again .. if you have a decent soil ....

e.g. un-named lawn fert seller has a 4 bag system of lawn fert ... i found out.. getting cheaper as i go older .. that i got the same lawn.. if i only used 2 bags ... the lawn just didnt need that much .... do NOT pay for marketing ....

i found out when i moved from my small suburban garden [wonderful deep soil] .. to 5 acres [yellow mineral sand] .. that just about everything will live with no fert at all .... and grow just fine ... i am too cheap to buy 50 bags of fert to cover 5 acres ....

roses and high production flowering plants [as well as the veggie garden and maybe some fruit trees ].. need a fert regiment .. just about anything short of that ... will do just fine with proper water.. even on my nearly sterile soil ..

i do always keep a bag of 12-12-12 [or 16 or 19-19-19] in a 5 gal water proof bucket.. and throw an LITTLE bit around stuff that looks like it needs a boost ... and i have had that bag for 3 years on 5 acres of gardens ...

if you decide to use something.. it wont have to be all that much ..

it is usually said.. to start with a soil test.. to see if anything is lacking from your soil ... and if there isnt.. do not add anything ... IF your test shows a little nitro will help.. then add some.. but never just walk out there and willy nilly start throwing stuff around ... again.. IMHO ....

good luck

ken

PS: osmacote is engineered for use in pots.. where watering flushes all nutrients from the pot repeatedly ... and has differing time formulas ... from 4 to 9 months ...
IMHO it is prohibitively expensive to use in mother earth because you are paying for the engineering .. and will kill plants if you are using the 9 month time release in you z6 garden that most likely only has an 7 to 8 month garden season ... skip it unless you do all the research ... and buy the right stuff ... just because some nurseryman.. or nurserygal wants to sell it to you with the plant ... does NOT mean it is NECESSARY .... tread lightly ...

There are quite a few ornamentals that bloom better with regular application of organic matter and many soils that do not qualify as "basic, decent soil".

I agree with most of what gardengal has to say, except that I couldn't possibly mulch everything in the compost that I am able to produce so I rely more heavily on horse manure, which we have in great quantity in my area.

I would also point out that some of the feeds that can be used as fertilizer (feather meal, blood meal, cottonseed meal) may contain quite a lot of nitrogen or may have unusually high or low pH. My recollection, for instance, is that cottonseed meal is pretty acidic. See what's commonly available in your area and look it up first, so you know how to handle it.

Organic fertilizers can be applied at any time, including winter. They will not do much before the weather warms up, but they also do no harm - they'll just wait for the right time to start to break down. Useful to know if you get a nice day and just want to putz around outside- or if the manure-toting capactity of your car is limited!

My personal favorite fertilizer (other than horse manure) is alfalfa pellets. Cheap, simple, hard to overdo, easy to use, fragrant (at least until they start to break down). I apply once a year, in the spring, to everything except the "lawn", which never gets anything.

In response to Ken's comments, I'd just like to add that soil nutrient levels are not unlimited and as plants grow and mature, nutrients are removed from the soil and need to be replaced......somehow. Whether this is accomplished through an organic mulch (like compost or composted manures) or via prepared fertilizers (organic or non-organic) is the gardener's choice but it is not reasonable to assume that no attention to the nutritional requirements of the plants will result in continued good health and optimum growth.

I don't think anyone is assigning human qualities to their plants and I hope no one is making the assumption that fertilizers are 'plant food' - they are not. Plants make their own food through the process of photosynthesis but the nutrients required for this process must be available in sufficient quantities for that to happen efficiently. And depletion of basic nutrients does happen over time, especially that of nitrogen. Applying OM will alleviate this but as leslies states, a number of organic products sold as fertilizers will accomplish the same.

And leslies, I don't produce anywhere near the volume of compost I require for my garden so I purchase it in bulk :-) I'd go through about 20cy twice a year in my old garden! I do prefer compost to manures, primarily because of a broader range of nutrients available and because there is no weed issues with local municipal compost products. But everyone will have their own preferences. It is just important to remember that nutrient replenishment through whatever your preferred method might be will be necessary in any established garden.