Since this is a common subject, and one with varied opinions, I'd be interested in others opinions and their reasons & seasons why & when they use N-P-K and other fertilizers. Just a word of caution: I am not a strict organic farmer- so do not want to offend anyone against non- organic methods--- I use when I can, but I am not religious about it...).

I grow hoyas, orchids, many roses, currants, gooseberries, raspberries and fruit trees ( figs being the majority!!:-). )

Spring: I use all fertilizers in Spring on established in ground plants as new growth emerges. Probably the only time I use nitrogen -(N). I also use superPhosphate to encourage blooming and root health. I stagger this with a mycorrizal fungi to improve soil health and balance. Espoma makes good mycorrizal products) If the plants are potted I am very careful to avoid nitrogen unless it is slow release and low in number. I have fried too many plants with nitrogen. On in ground plants I use a balanced compost with green matter ( N) phosphates and potassium P and K) with decayed brown matter soils ( leaves, coffee grounds, banana peels, etc)

Summer: i actually use superphosphate (P) and or potash (K) mid Summer to encourage fruiting and Magnesium sulfate if leaves look chlorotic or if the plants do ot seem to be using water efficiently.( constantly watering can mean low potash-potassium (K).

Fall/Winter. the plants are starting dormancy. The only thing I use on my potted indoor plants is Potassium and Phosphorus. These set up the stage for robust growth in Spring by getting roots going and encouraging blooms, if applicable. No nitrogen. I do not apply anything to in-ground plants except compost containing these elements... Like banana peel and decayed brown matter like leaves.

Superphosphate is probably my favorite, most heavily used lawn element...along with Magnesium sulfate. (epsom salts),...it achieves amazing results with least risk of burning my plants.

Sorry for any typos...using a tablet... PIA to type on....:-)

I have never heard of anyone using Potassium and phosphorus in the fall/winter. That is intriguing. But in reality you are just applying compost right? or did I misunderstand?

As far as my in-ground plants in Fall and winter, I only apply a light spread of compost, yes---ONCE. Brown compost, not green. Decayed leaves mostly...and they also serve as a mulch for winter protection if they are dry.

For my indoor plants, I tend to use an orchid bloom-booster type on all flowering and fruiting-type plants. These are mild enough to avoid burn in potted plants since orchids can be pretty fussy and are a good barometer for fertilizer tolerance. I dunk them in Grow-More Orchid bloom-booster and stir in some Mag-sulfate.

Grow More is a non-urea (slow release for plants in a more dormant state--i.e. growing inside under lights during winter) nitrogen at a neglible amount, 3(N)-30(P)-30(K).
I flush all my plants after an hour with water...and make sure they have good air circulation.

Don't overthink it.   A well balanced neutral fertilizer should be fine.   I go with a constant 200 ppm until Aug 1.   With figs, I think a neutral to slightly alkaline fertilizer is best.  I wouldn't bother with all of the junk folks will try to sell you in those hydroponic shops.  I go with a ratio of 3-1-3.

 

This years Maltese Beauty crop.   I've heard people say that heavily fed figs will produce less figs and more top growth, with the figs being produced having less flavor as well.  I don't have enough years under my belt to say this is true or not.  Common sense to me says otherwise.  It's also possible that people are referring to in ground trees rather than potted trees.  If your trees are in the ground, I think they would require far less fertilizer than what I give my pot trees.

Cheers 

I have a simple plan. Every time I water my plants I use manure tea made from sheep poop. Once a week I add Miracle Grow to it, that is until mid Aug. All my plants LOVE the manure tea and it is easy to make.

I just keep a trashcan of manure team going all summer. I start with a 3 gal pal of poop, then add water. As it gets low, I add more water, over and over and over. By mid-summer the tea is looking a little weak, so I add a shovel-full or two and keep adding water. It works great and is simple. I try to do all my watering with rain water so I just dump the water from the rain barrels into the tea as needed. It is one extra step, but I think it is worth it because we can see a big difference from when we used plain water and now. All my wife's flowers are booming!

Again, manure tea with all watering, with MC added once every 7-10 days

All that P, K, and fungi are usually unneeded and wasteful unless your soil or media are lacking. My inground trees get only nitrogen and very very little of that. Fruit brix runs 20-34, best I've ever grown. Potted are another matter because of leaching and media issues. Even there I've grown splendid fruit with mostly just enough added nitrogen to get adequate but not excessive growth.

You don't need P or K for massive bloom and fruit set. I thin off 50-95% of peaches, nectarine, apricot, and pluot. My figs set a fruit at every leaf axial.

P and K are limited resources and polluting in some circumstances.

Potassium encourages more flowers/fruits/quality and helps harden off growth.  I fertilizer my in ground trees twice this year with some blood meal, bone meal and potassium sulfate, not much, about half a cup each tree per time and then fish fertilizer, about half a litre.  Next year I don't think the in grounds need much fertilizer but I know I will for sure put manure at the start of the season.

For pretty much all my fruit plants I operate on the $100 hole for $5 plant philosophy, digging a very large hole, amending with compost/peat/etc and adding PlantTone as per the label. My area has horrid clay soil with lots of rocks. The first year I will use a diluted liquid fertilizer that is high in P-K for root promotion several times when I water. Beyond that I don't do a heck of a lot unless I see something specifically needing nutrients (usually iron deficiency on a handful of acid loving ornamentals since the soil pH is around 6.5). Also I use lots of mulch that breaks down pretty quickly.

Containerized plants are another animal...PlantTone in the mix, supplement with a little Miracle-Gro to give them a jump start. After a while (2nd year) I'll use some high N fertilizer tablets. Once things are proven hardy I intend to get pretty much everything in the ground, the potted plants are either back-ups or not quite large enough to plant out yet.

Overall one needs to be careful with fertilizing fruit trees (not specific to figs), excess fertilizer can reduce bloom and fruit since plants will grow vegetatively to use up the abundance of nutrients.

i'm doing what daniel is trying. when i wanted figs on my inground trees i used blossom booster. that's high in P and K, lower in N.

the trees formed figs in weeks. that's how i treat flowers. 10-10-10 early, blossom booster later.

gene's way is better but my sand and gravel is close to sterile. no worms, things don't decay. i dug in 2'' of compost this year but for now i must use chemicals.

The best thing would be to get a soil test every year or two.  Soil tests are really not much help for N needs as it will both leach and volatilize.  However, continual application of unneeded minerals will cause other minerals to be less available.  pH levels also change mineral availability.  I'm no expert on fig mineral needs.  It does seem from reading here that figs prefer an alkaline soil.  I would not want to drive the pH to greater than 7.5 because it will make many other elements much less available.  I would recommend Logan Labs as a very highly regarded testing laboratory.  They give results for many of the trace elements that can be very important for some crops.  Copper, boron, zinc, and manganese are probably important for figs as well as the larger components of calcium, magnesium, phosporus and potassium.  Logan reports them all.  I don't know if they are set up to give application rates or adjustments for figs.  Cost is about $25 and well worth it.

Adding some nitrogen using milorganite should do it.  More compost is always better as it becomes available as nitrogen when the microbes devour it.  fortunately those microbes are more active when figs and grass are most actively growing.  Those microbes will also cause some unbinding of the soil minerals.  The Espoma product with the mycorrizal fungi will send out the strands to seek out water and nutrients for the plant and the soil microbes.  That is what improves the soil structure over time.

I have not searched for it but I would guess that one of the ag oriented universities has done some research for nutrient needs for figs.  Maybe figs are not as important as corn, beans, wheat, or golf course turf but those guys are always looking for a new field to explore so they can get published.

I use a liquid Tomato fertilizer + Epsom Salts + Azomite with pretty good results on my potted figs.
I have been posting the photos, good size and taste.

ok heres my 2 cents on the whole thing.

figs respond to min amounts of fertilizer. so here is what i do.

when ground thaws out treat with bone meal to increase root production. once first buds break i treat with blood meal for new growth. top dress with last years compost and work it in the top three inches. this is the organic path but it works for me her in illinois. i mulch deep with fresh cut grass. deep to harbor the microbes to start the composting and burn the weeds that may grow while improving my soil and drainage at the same time. every year my crops only get better.

like i said its what works for me. you gotta try lotsa things and find what works for you. also i use super thrive once a month.

Is anyone adding Texas Greensand to their fig soil? I have read it is very helpful for certain kinds of fruit such as currants. Since fig taste is very influenced by local culture, I wonder if the micro-nutrients in Greensand would make a difference in the flavor? Or am I just dreaming of a way to supercharge the fig taste I love so much?

Gascony,
Here is my current schedules, I disagree with the often used comment that "fig trees need little fertilization", although they can grow almost anywhere in almost any media, they will grow healthier and produce more figs with the addition of a balanced fertilizer, attention to the soil and regular watering.

I use Espoma Garden-Tone @ 3-4-4 NPK and I supplement with Miracle-Gro All Purpose fertilizer @ 24-8-16, which is a 3-1-2 ratio. At full strength application, the tips of young leaves sometimes experience "fertilizer burn", so pre-watering the soil before fertilizing with Miracle-Gro may be necessary.

The Organic Espoma contributes micro-nutrients and mycorrhizae to the mix, in addition to other insoluble nutrients. The Dolemite Limestone adds Calcium and Magnesium, which are introduced over time as it breaks down with the other insoluble nutrients and the microbial action in the soil from the fungal and bacterial cultures (mycorrhizae). The Ironite adds Iron and other micro nutrients. The Espoma-Tone, Limestone and Ironite act like slow release fertilizers. The potted trees are watered daily, so the potting mix is always kept moist and never allowed to dry out. The Miracle-Gro can be replaced with any other balanced water soluble organic or chemical based fertilizer. There are several Hydroponic fertilizers that may perform better, I'm currently trialing General Hydroponics MaxiBloom 5-15-14 NPK as a replacement for Miracle-Gro for potted fruiting plants. 

Potting Mix;
5 - parts Pine Bark Mulch
1 - part Peat Moss
1 - part Perlite
1 - part Oil Absorbent(Fullers Earth @ Tractor Supply)
Plus - 1 cup Dolemite Limestone and 1 cup Espoma Plant-Tone per 5 gallon.
Plus - 1/4 cup Ironite mineral supplement per 5 gallon.

Fertilizing Schedule for Rooted Cuttings:
Weekly feedings of Miracle-Gro All purpose @ 1/2 teaspoon / Gallon of water for cups and increasing to 1 tsp / Gallon for well rooted cuttings and 1 gallon containers, with 1/4 teaspoon Epsom salt / gallon.
Monthly Feedings of Espoma-Tone @ 1 -2 tablespoons per 1 gallon container.

Fertilizing Schedule for 1-2 year old potted fig trees:
Weekly feedings of Miracle Grow General purpose @ 1 tablespoon / Gallon of water with 1/2 teaspoon Epsom salt / gallon.
Monthly Feedings of Espoma-Tone @ 1/2 cup and Dolemite Limestone @  1/2 cup  per 5 gallon container.
Miracle Grow and Espoma are stopped at the end of July or mid August to allow for "hardening off".

Fertilizing Schedule for 3 years and older potted fig trees:
Weekly feedings of Miracle Grow General purpose @ 1 tablespoon / Gallon of water with 1/2 teaspoon Epsom salt / gallon.
1 cup of Espoma-Tone at start of season.
Miracle Grow is stopped at the end of July or mid August to allow for "hardening off".
I will be looking for 2-3 feet of growth at the fruiting branches yearly.

Fertilizing Schedule for In Ground trees; 1 time in early spring.
Dolemite Limestone/Epsom Salt/Borax (80/4/1 ratio, Mittlieder Gardening pre plant mix) @ 2 cups / 50 Sq Ft.
Espoma Garden Tone @ 2 cups / 50 Sq Ft (to inoculate the soil with microbes).
Soak tree drip line with Miracle-Gro All Purpose @ 1 tablespoon / Gallon of water.
Layer of compost and a layer of Mulch all under the drip line.