Can You Use Vegetable Fertilizer On Flowers?

I think I speak for all gardeners when I say there are too many different fertilizers to choose from! Growth fertilizer, bloom fertilizer, blueberry fertilizer, rose fertilizer, tomato fertilizer – the list goes on and on.

What if you want to keep it simple and just use one type of fertilizer for all of your plants? For example, can you use vegetable fertilizer on flowers?

Vegetable fertilizer is perfectly suitable for growing flowers. All-purpose vegetable fertilizer is an excellent choice for feeding flowers. Avoid adding too much phosphorus, as this can lead to less blooms and other plant issues.

Garden tone fertilizer bag
Is vegetable fertilizer okay for flowers?

In this article, I’ll explain why “bloom” and “flower” booster fertilizers may actually do more harm than good. Instead, I recommend fertilizer with a lower phosphorus content. 

Different Types of Fertilizers

So, what are the main types of fertilizer you’ll find on the market?

  • All purpose fertilizer. These fertilizers are general-purpose, made to add a wide variety of essential plant nutrients. They typically contain all of the primary and secondary nutrients, along with trace elements for a well-balanced plant diet.
  • Growth stage fertilizer. Some fertilizers are formulated for the growth stage of plants. These will often contain more nitrogen than anything else, leading to lots of healthy leafy growth.
  • Flowering stage fertilizer. Many fertilizers are targeted at the flowering stage of plant growth. They often contain more phosphorus, and sometimes added potassium, claiming to increase the blooms on a plant. However, this is not true (and we’ll talk more about that later).

Whether it is a liquid fertilizer or granular fertilizer doesn’t really matter. The elemental makeup of the fertilizer is what is important.

The problem with most fertilizers is the marketing behind each type. “Rose fertilizer” is usually more expensive than “all-purpose” fertilizer, as it is made for a specific purpose. But is it really any better?

To find out, let’s talk about the contents of each fertilizer. Learning what NPK means will help you choose the right fertilizer for your flowers.

Best NPK Ratio For Flowers?

If there’s one thing you should know about fertilizers, it is the N-P-K ratio. This refers to the 3 numbers you will always find on fertilizer packaging.

These three numbers indicate the amount of nitrogen, phosphorus, and potassium (respectively) in the fertilizer. For example, a 3-4-5 fertilizer contains 3% nitrogen, 4% phosphorus, and 5% potassium. These are the primary nutrients used by all plants, hence why the quantities are so important.

An important thing to understand is that flowering plants have very similar needs to other types of plants. They require all of the same nutrients that vegetables and other plants need.

So what is the best ratio to look for when growing flowers? Generally speaking, flowering plants grow best with an NPK ratio of 3-1-2. In fact, this ratio is a good rule of thumb for all of your plants, flowering or not.

Miracle gro fertilizer NPK
Miracle Gro plant food uses a 24-8-16 (same ratio as 3-1-2, only more concentrated).

Too much of any nutrient can cause growth issues.

For example, too much nitrogen can lead to lots of leafy growth, at the expense of blooms! This may cause lower vegetable yields, or reduced flower production.

Too much phosphorus can lead to nutrient uptake issues, potentially leading to growth problems in your plants. Plus, most soil in North America has more than enough phosphorus, so adding more isn’t a good thing.

So why do “flowering” fertilizers always have more phosphorus? Miracle-Gro “Bloom Booster” is rated at 10-52-10!

It stems back to when farms would deplete phosphorus in their growing fields. Adding phosphate back to the soil increased productivity. So, phosphorus was quickly seen as the flower booster.

However, if your soil doesn’t need phosphorus (and it probably doesn’t), adding more will only lead to problems.

Yellow roses in full bloom.

Getting a soil test is the only true way to know what your garden soil needs. Most home gardeners add too much fertilizer, so it is actually best to err on the side of caution and go light, especially on the phosphorus.

Best Flower Fertilizer

I get it, you want more flowers. Who doesn’t? But “flower fertilizers” are probably not the answer! They cost you more money, and add unnecessary ingredients to your soil.

Instead, try to find a fertilizer with a 3-1-2 ratio, or a similar ratio (24-8-16, 6-2-4, etc.). This ratio is approximately the amount of NPK found in plant tissue, hence why it works as a fertilizer.

Best fertilizers:

Various fertilizers
Find fertilizers with less phosphorus, and more nitrogen. But don’t over-apply!

It is most important to try to find fertilizer that does not have ridiculously high phosphorus content. Vegetable fertilizers are usually formulated well for both veggies and flowers, so something all-purpose is a good bet.

It is much more likely that your soil lacks nitrogen than phosphorus or potassium. Nitrogen is critical for your plants to produce healthy leaves, stems, and roots.

Just as important as the nutrient content is the amount of fertilizer that you apply. Never assume that “more is better,” it’s not! Always feed your plants at or below the recommended levels on the packaging.

Some fertilizers are much more concentrated than others, so be careful to follow instructions and not to over do it.

Calvin with large pink peony bloom
Peony blooms – these plants haven’t been fertilized in years!

To be on the safe side, get your garden soil tested. If your plants are showing signs of stress or have less blooms than you’d like, then you may need to fertilize. If you are adding fertilizer just for the heck of it, you might be making a mistake!

In many cases, adding organic materials such as compost, animal manure, leaf mold, or worm castings is enough to enrich your soil each year. Vegetable plants are heavy feeders, so they may require more frequent fertilizing than some flowers. However, the type of fertilizer used can usually be the same.

When To Fertilize Flowers

If you plant on fertilizing your flowers, when is the best time to do it? For best results, I recommend fertilizing in early spring to ensure the soil is rich for the season ahead. This applies to both garden beds and container plants.

For water-soluble fertilizers, apply at the recommended rate, or at a reduced rate to be safe. For slow release fertilizer, mix it into the first few inches of soil, ideally 2-3 weeks before planting. It helps to feed the soil before planting to aid in root development after transplanting.

For perennials, such as roses, hydrangeas, agastache, and sedum, fertilize in late winter or early spring. If your plants re-bloom, you can also apply a light top dressing mid-season to encourage more flowers after deadheading.

Purple coneflower echinacea purpurea flowers
Purple coneflowers in garden bed.

For annuals, prepare the potting mix or in-ground soil a few weeks before transplanting outdoors. You can also add a bit of fertilizer right into the planting hole as you transplant to encourage strong root growth.

Organic matter needs time to break down, hence why it is important to feed a bit before planting. If your plants are showing active signs of deficiency, you can use a liquid fertilizer to feed the plants quickly.

Why Aren’t My Plants Flowering?

If your neighbor’s plants are full of blooms, but yours are lacking, what might be going on? What causes individual plants to not produce flowers?

The most likely reason your plants aren’t flowering is an excess of nitrogen or phosphorus. At high levels, these two nutrients can cause less blooms.

Cosmos flower
Lots of foliage and no flowers indicates excess nitrogen in the soil.

If your plants are big, green, and healthy looking, but lack flowers, it is most likely too much nitrogen in the soil. Avoid fertilizing and allow the nitrogen to get used up.

If your plants are stunted, or have yellowing or unhealthy foliage, then there may be too much phosphorus in the soil. Again, phosphorus can lock out availability of other vital nutrients like nitrogen, iron, and calcium.

Plus, phosphorus does not leech out of garden soil easily, as it binds to soil minerals. So, to reduce phosphorus in the soil, you have to grow heavy-feeding plants like tomatoes or brassicas.

So, instead of adding more nutrients, consider reducing your fertilizing habits for a season to see what happens. You’ll probably be pleasantly surprised at how productive your un-fertilized flower garden can be!

Final Thoughts

In general, try to avoid buying fertilizer for specific plants, especially flowers. Most plants have the same basic nutrient needs. Vegetable plant food is probably a better option than flower fertilizers.

It is most important to keep an eye on your plants for signs of stress (nutrient deficiency, slow growth, etc.) and get a soil test to know for sure what is in the soil. For consistently healthy plants and beautiful flowers, a soil test is the best choice you can make.

Poppy flowers blooming
Pink poppies blooming.

So, whether you’re growing tomato plants or climbing roses, the fertilizer you use can be the exact same. I recommend looking for fertilizers that have a lower P number in the NPK (less phosphorus). However, most balanced NPK fertilizers will do the trick for healthy, floriferous flowers!

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