In Stardew Valley, only one fertilizer may be used per farm tile. With about three broad categories of fertilizers, that being Quality, Speed, and Water Retention, this is a major opportunity cost to consider.

Chances are (Though I have no hard statistics) you, yourself, probably only use quality fertilizers. Though water retention is obviously pretty easy to rule out, it makes sense to focus on quality over the speed varieties as they are both cheaper (if not more straightforward) to make than speed, and coincides with the most straightforward crop strategy of "Plant as many of the highest GPD crop you can".

However, as my previous guide on "The Value of Lesser Crops" outlines, raw numbers don't tell the whole story. Speed-Gro is a very strong option that, with a little judgement in your crop choice, can propel your mid-game to new heights.

Thus begins my case for Speed-Gro:

Speed-Gro reduces the total growth cycle of a crop. If Speed-Gro is in effect on the earliest stage of the crop (Speed-Gro can be applied later than the initial plant, but its generally not worth it), the crop's total growth time before harvest is reduced by bare minimum 1 day, rounded up. This means a 4 day crop grows in 3, and a 12 day crop in 10, despite being a 0.4 day and 1.2 day reduction on paper.

Think carefully about those last two values. Effectively, the growth increase is rounding up a 0.4 value up to 1 day. Because of this rounding effect, Speed-Gro disproportionately improves faster growing crops over longer crops, getting applied each time a crop is replanted.

Take the humble Parsnip. A standard plot grows 6 Parsnips each Spring. With Speed-Gro, that becomes 9 harvests. The written "10% Increase" is instead a 50% increase in total crop count.

50% more crops sounds much more appealing than 10% "growing speed", doesn't it?

As mentioned before though, Speed-Gro does not exist in a vacuum. Basic Fertilizer is its closest comparison, and it has a whole slew of its own benefits.

The argument for stronger Speed-Gro and better Quality fertilizers become more complex further in, so it is best to stick to the basics with Basic Fertilizer.

You're likely familiar with this staple early-game stepping stone. Perhaps a mainstay through your whole game. But before jumping into the full discussion, it's best to get some hard numbers.

This wiki page[stardewvalleywiki.com] on the Stardew Valley wiki details the hard numbers to what Basic Fertilizer is actually doing for your crops.

At level 0 Farming with unmodified soil, quality of crops causes on average a 1.01x increase, or 1% increase in value. At level 10, quality grants 19% increase in total value.
Basic Fertilizers at level 0 has a 4% increase to profits, while at level 10 it is a 32% increase.

It's best to compare the unmodified values to the relevant fertilizer instead only looking at the base numbers.

Taking the difference between the modified soil, this means the benefit of Basic Fertilizer is effectively a 3% increase in value at level 0 and 13% increase at level 10.

This means that Fertilizer heavily depends on your Farming level to get their value. The 13% difference at level 10 Farming can be used broadly to describe the Basic Fertilizer as a 13% increase in crop value.

Now that both equivalent fertilizers are better understood, it is time to ask: Which is better?

At 2 sap per craft, available near immediately at level 1 Farming, it grants an increase to profits that ranges based on the Farming level, becoming better the closer to 10 or 14 Farming one is. Further, its very broad effect means any crop improves its value, though more harvests become closer to the average. Higher value crops in smaller bulk can swing one way or another.

Furthermore, quality is helpful or necessary in certain parts of the game. The Community Center requires a handful of gold-star crops for instance, and higher quality crops are useful for gifts and for events.

Being very basic and easy to use, the one problem Basic Fertilizer faces is the fact it just doesn't do much at low levels. Level 1 is looking at about a 5% increase. It helps, but won't be revolutionizing your income.

Pros:

- Exceptionally cheap
- Useful on every crop
- Quality crops useful for various applications

Cons:

- Underwhelming effect at low farming levels
- Not very useful very early game


Speed-Gro, in contrast, deals in the quantity-over-quality method.

Normal Speed-Gro is 1 Pine Tar and 5 Moss. Moss greatly depends on the Green Rain event to gather in bulk or using Green Rain trees to mount production, otherwise it is the Pine Tar that will be the greatest hurdle. A fairly strong Pine tree farm is required to get a major supply, costing lots of wood and copper, lest one waits past year 1 in mid Spring for a 100g buy-in per tile.

Thankfully a craft gives 5 doses of fertilizer. A good Pine farm is still thus required but a farm-spanning one is not needed to fill the equivalent space. Throw in a few Green Rain Trees for the improved moss-growing effect and it can be self sufficient in supplying the moss too.

If using a fast growing crop of 4 days, it turns its modified 6 harvests per month to 9 for a 50% increase in total crops and thus total sales. This benefit is useful at any stage of progression Farming wise, albeit a fair bit of investment implies proper use of Speed-Gro will take bare minimum a month or two if pursued as quickly as possible, implying a handful of Farming levels before this fertilizer kicks in.

50% more crops can be useful in itself for more potential for cooking or other purposes. As the bottleneck for gifts is 2 per week per villager it may be preferred to have quality for gifts over quantity.

Focusing on faster crops has a secret advantage of re-investment. In short, being able to harvest and sell earlier than longer growth crops gives either a self-compounding ability to plant more crops over time, or flexibility with your funds to cash in part way on other parts of the game. Though it is unfortunate this field-expanding ability conflicts with how difficult it is to gather the fertilizer in large quantities.

Finally, as Basic Fertilizer has no bearing over Farming XP in itself, the nature of harvesting more crops overall can result in much faster Farming XP gain in the long run.

Pros:

- Up to 50% increase in profits
- Can deepen stock of crops for various purposes
- Great at re-investing to expand crops later
- Effectively more Farming XP

Cons:

- Very expensive to mass produce
- Implies large, sprawling farms to make the best use
- 50% Profit increase is on lower value faster crops, which don't out-profit the 13 day crops

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Laid out this way, it is clear that Speed-Gro has a lot of good merits to its use. Its focus on faster growing crops means it will likely not make more profit than Basic Fertilizer growing Melons or Pumpkins, but keep in mind the stocking effect can aid in cooking supply as well as Farming XP indirectly getting boosted.

The re-investment effect is nothing to sneeze at either. Low tier crops like Radishes alone can be justified for using simply because their compounding effect works well at low money levels, an inevitable hurdle in the early game. Speed-Gro mounts this effect with profit boosts to match quality fertilizers.

The focus of this discussion has been solely on Basic Fertilizer and Speed-Gro's first tier to keep this discussion simplified.

As presented before, Speed-Gro has good utility benefits at the cost of being harder to use. Requiring larger farms and steeper crafting costs to really use.

"Quality Fertilizer" and Deluxe Speed-Gro change the discussion drastically, as Quality Fertilizer now needs some preparation in having cheap fish to craft, and Deluxe Speed-Gro having a debatably equivalent 1 Oak Resin and 5 Bone Fragment with a 25% growth speed improvement over 10%.

The simple-no-brainer Basic Fertilizer now needs an inch of preparation to use, and the Deluxe Speed-Gro is not universally good in the same cases as Speed-Gro given that its use revolves around plants that exploit the rounding effect.

So, let's begin breaking this down.


Quality Fertilizer's 1 Fish is best supplied with Crab Pots, as its automated nature and lower value fish in the mix make good fodder for this purpose. The Sap is about the same rate as Basic as its 4 sap to 2 Fertilizers, thankfully meaning its also 1 Fish for 2 products.

It is also best to narrow the Farming Level debate from level 9 to 14, as level 9 Farming is required to craft, and this stage of the game it's likely Farming food buffs are available enough to be used consistently.

Quality Fertilizer at level 9 Farming is a 16% profit increase compared to no fertilizers, while level 14 Farming is 19%.

Comparing Basic and Quality directly at these levels is a 6% and 8% difference respectively. Perhaps small on paper but is relatively low-invesment to craft. Sap cost is unchanged, and though Crab Pots are not negligible to manage it is a money/resource generator in its own right that one may use just for its own sake anyway.

Deluxe Speed-Gro, on the other hand, is not so simple.


25% growth speed over 10%.
This is gonna take some explaining.

So, the king 4 Day crops are fully unchanged. Still 9 harvests in one month.

However, Agriculturalist.
That profession that's always passed over for Artisan?

Catapults the harvests to 13 harvests per month. This over doubles the default 6 harvest baseline. Literal 100% profit boost. That said, an obvious alternative is trying to see if this baseline 25% growth speed is useful anywhere else.

A 6 day harvest crop is 4 harvests per month baseline, 5 with base Speed-Gro, 6 with Deluxe Speed-Gro, and 9 with Deluxe+Agriculturalist.

13 day crops offically achieve a 3rd harvest over just 2 at baseline, only needing Deluxe Speed-Gro alone.

Naturally at this point the numbers are gonna need some crop value context to mean anything as three very different scenarios are being compared. The following includes various Spring crops as an example, chosen for the highest overall sell value minus the price of the seed. These should be the most optimal crop for their growth time.


As the number of harvests suggest initially, the profit boost of the Deluxe Speed-Gro is more pronounced on the 4 Day baseline Garlic, over doubling its value at a 116.66% increase. Kale gained 80% value, while Rhubarb gained 50%.

One may notice that the Rhubarb/Kale overall sell for more than the Garlic, despite the overall value increase being higher for Garlic. Again, keep in mind the utility. Farming XP, item stock, and most especially reinvestment are the key benefits. Fertilizing a high value crop like Rhubarb is overall more profitable standalone, but throwing down a handful of Garlic can let you get more money in the long run if you're starting from lower funds.

Thus begs the key takeaways:

Let it be abundantly clear that the end lesson for this guide be that Speed-Gro is not objectively more profitable than Fertilizer.

Leveraging massive numbers of Star Fruits grown with either Quality or even Deluxe Fertilizer will beat out any combination of Speed-Gro that can be mustered.

The value in Speed-Gro lies in literally speeding-up your mid game progression.

Its disproportionate profit impact on lower value, faster growing crops makes it more forgiving for smaller wallets. Starting from these smaller crops with lower cash is always better than going for the beefy 13 day crops in the first place, as you gain money earlier you can respend on more crops (The key step in beating out the longer crops), or cash out early on whatever other progression upgrades are needed elsewhere in the game.

Speed-Gro exaggerates the advantage to this strategy, as the 50% harvest/profit increase it boasts far beats the 7% to 13% profit bonus the Basic Fertilizer offers. If already growing 4 Day crops for the above reason, Speed-Gro makes them far better.

Speed-Gro is also beneficial regardless of Farming Level variance, and can even help increase Farming XP in itself thanks to the reinvestment effect plus overall more harvests. Having more crops overall can be helpful if pursuing crafting/cooking as well.

However, if money is no object, if the field can be filled as much as one's willing to deal with as it is, if there are no plans to expand any further, if farming level is already near its peak, slower growing crops benefit far more from that consistent 10%-ish boost.

Speed-Gro will be left behind nearing the end game, so give it a try next time you start a new file. It may help a lot in trying to juggle your tool expenses with your farm and building upgrades.