I bought and planted a new bare root floribunda rose about a month ago. It's doing well. I have Miracle-Gro All Purpose Water Soluble Plant Food (not their rose fertilizer). They told me on online chat to mix one tbsp of fertilizer to a gallon of water every 7-14 days. My problem is I don't know how much of the gallon I should give the plant, approximately how many ounces? Thanks.

Give it the whole gallon, dowsing the plant as you do.

It is a new rose.
What you have will work but a dedicated rose fertilizer will work better.

I might go half strength at the most for the first few months if a significant amount of the soil from the store pot was put in the ground. That could have time-release fert in it.

I, usually also give my new plants some form of root boost; for decades I used SuperThrive but it has gotten excedingly expensive.

The recommendations for the Miracle Gro granular product call for an obscene amount of fertilizer. The instructions are designed to sell fertilizer, not to meet your plant's needs. Try a quarter tbsp per gallon, or less, and pour the whole gallon on (maybe in a couple of passes, separated by a few minutes).

Baja, clarify your reasoning for me. The NPK of Miracle Gro is 28-8-16, or a ratio of 3-1-2, recommended for most plants by many authorities. Because the NPK indicates the percentages of those nutrients in that package by weight, and that product is designed to be diluted to one tablespoon to one gallon, or 1:256, how is that an obscene amount of fertilizer?

Now, whether healthy garden soil actual needs fertilizer at all without determination by soil testing is another issue altogether, but compared to the majority of fertilizers in the stores, especially "bloom booster" formulas, MG seems okay.

1 tbsp per gallon of 24:8:16 works out to be over 1000 ppm N in the final solution. Here is a handy calculator to use with any product and arrive at a working concentration.

https://firstrays.com/fertiliz...

For comparison, the dosage I give my cacti and succulents (same MG granular product) is less than 1/20th (5% of) this amount. I can't really imagine any situation where more than 200 ppm N would be needed on a regular basis, especially when there is organic matter (compost) in the soil.

Thank you for that explanation Baja, very helpful and enlightening. I've bookmarked that calculator.

Baja_Costero said: 1 tbsp per gallon of 24:8:16 works out to be over 1000 ppm N in the final solution. Here is a handy calculator to use with any product and arrive at a working concentration.

For comparison, the dosage I give my cacti and succulents (same MG granular product) is less than 1/20th (5% of) this amount. I can't really imagine any situation where more than 200 ppm N would be needed on a regular basis, especially when there is organic matter (compost) in the soil.

Roses are not cacti.

Roses are known as heavy feeders, even if the soil they are in is considered "good" soil.
More is better, on a whole.
Too much Nitrogen gives you a very green bushy plant that does not blossom as much as it should but too little Nitrogen gives one yellow leaves and a less healthy plant.

I generally feed my roses with 5 gallon pails in which I add as much fertilizer as decades has given me a feel for.
I always douse my roses but then I normally also add bio-fungicide to the watering pail.
For new roses I am a bit more precise about what I do, using rooting fertilizer

All that said, this is a new rose, and it would be better to get a phosphorous rather than a Nitrogen heavy fertilizer until the rose has grown six inches plus or minus.
I ALWAYS add chelated Iron when I plant or fertilize.

https://heirloomroses.com/blog...
Roses are heavy feeders. A healthy, well-fed rose will produce more blooms and be better equipped to ward off disease and illness.

I realize roses are different from cacti, which is why I didn't recommend the amount I use for cacti. I recommended 5 times as much. But I have never seen any practical application where the amount needed for healthy plants remotely approached the MG recommendation (over 1000 ppm N). You can definitely add more fertilizer than you need if you want, provided you aren't burning the plant. But I really don't think that is necessary here. I would defer to anyone who has ever tested the actual quantity required for roses (which I have not).

Yes, RpR, with roses you would certainly have to stay on top of disease/insect problems with they amount of fertilizer your purport. Another reason why I also would not recommend such a high dose.

Obviously, through the decades you have found what seems to work for you, but the Thread OP is new to growing roses. Roses in Tennessee are more easily prone to disease and insects than in Minnesota. I don't think he/she is ready to take on a schedule of disease and insect prevention applications.

@tomtenn : Don't fertilize your rose with anything yet!!! You said you planted the new bare root rose last month. The general recommendation is to only water a newly planted bare root until it blooms for the first time, since the new bare root is growing delicate new roots. Once it blooms, you can apply some fertilizer.

Though I'm no expert, I'd tend to lean towards what Susan says.

Tripling up on the advice to wait on fertilizing as the delicate feeding roots need to develop in order to take in the nutrients without which, the other roots could get burned. Best of luck! And I hope it has fragrance.

How does liquid fertilizer burn roots?
She said it is growing well and how to use the mixture she was informed to use.

I have planted dozens of roses in forty years, rarely using other than liquid fertilizer.
I have no set method but generally used root boost, when I soak/bank the canes, most often soaking them at least 24 hours, maybe more.
The only problems I have are the big box store supposed bare root roses that really have no roots left after they package them.
Those often go belly-up over the winter.
I have never seen a burned root; as pissant as they are when one buys them, I am amazed they grew at all.

If I do use dry, I put slow release into the layer the roots will grow into eventually.

It has to do with osmosis. Most soluble fertilizers are composed of various ionic salts (like ammonium nitrate, potassium sulfate, etc.). When the salt concentration of the fertilizer is greater than the salt concentration of the cells in the roots, the water flows from the cells to the surrounding soil with the fertilizer in it. This can desiccate the new delicate roots. The recommendation to wait until the bare root has bloomed to fertilize is a good rule of thumb to prevent people from dousing them with an overly concentrated solution of fertilizer while their roots are very young and tender. It's the reason that IV drips are usually 0.9% sodium chloride, and why cucumbers shrink when put in a concentrated solution of vinegar and salt.

Susan ..

You are correct about

When the salt concentration of the fertilizer is greater than the salt concentration of the cells in the roots, the water flows from the cells to the surrounding soil with the fertilizer in it. This can desiccate the new delicate roots.

,
but there is an easier way to control the possibility of root burn and still feed your roses.

When I first started growing roses .. decades ago ... I was taught that if you deep water, for in ground roses, or saturate the soil for roses in a container the day before you feed them liquid fertilizer, the roots are fully saturated with moisture and will not gobble up the fertilizer salts to the point where they will be damaged.

Then go ahead and feed your roses lightly and often until they are more established. As the plants get more established, you can increase the concentration of the fertilizer, but I still make sure that I always water the day before feeding.

I have followed this practice since those early days of growing roses and have never experienced root burn on any of my roses.

Smiles,
Lyn

Lyn, you're completely correct about the importance of watering well before using a soluble ("liquid") fertilizer. I use them frequently, and always follow that procedure, which is Rule #1 for using soluble fertilizers. I originally responded to the OP's question about fertilizing new bare roots, and then the further question from RpR asking "how does liquid fertilizer burn roots?".

Fertilizer may be great, but nothing beats a couple of bananas for making roses bloom.

Or a smoothie...