Fertilizing Roses and Shrubs

Fertilizing roses and shrubs at a garden center near me in Southern California.

Written by David S.

The key to beautiful shrubs and roses is soil health, and that means managing the soil’s nutrient load. Fertilizers are the primary method by which to do that. They are either organic or synthetic, and while they have the same blend of chemicals, they act differently. For example, If you apply a synthetic fertilizer too soon, it will likely damage the plant. The trick to managing soil nutrient levels is to provide the right fertilizer at the right time. Inside, we walk you through the best way to fertilize roses and shrubs. 

Use the Right Product

There are many products available for fertilizing roses and shrubs. EB Stone offers several quality fertilizers that are specialized for specific plant types. For example, their Rose and Flower Food is an excellent choice for roses, but not necessarily for shrubs. The lesson here is to use the right type of fertilizer for your plants.

Another essential feature is that shrubs have different requirements. What works well for one type of shrub might not work well for another. Be sure to check with our garden experts for fertilizer recommendations for specific kinds of shrubs. A good example is evergreen versus deciduous. How and when you fertilize depends on the shrub. The same is true for pruning.  

A Word About Fertilizers

Fertilizers come in ratios of nitrogen, phosphate, and potassium. Those are clearly labeled with numbers on the box or bag. For example, EB Stone’s Rose Food is 10/12/6, which translates as 10% nitrogen, 12% phosphorous, and 6% potassium. The ratio is always written in the NPK – Nitrogen (N) – Phosphorous (P), Potassium (K) – formula. 
Further, Fertilizers come in liquid, solid, granular, and time-release formulas. Some are simply dumped on the soil, spread, or applied with a folier (hose attachment.) 

There is also a relationship between the soil’s microbial population of beneficial organisms and fertilizers. Nitrogen, for example, must be converted to a usable form before plants can take it up in their roots. That little fact points to the importance of soil health and roses and shrubs that thrive. 

Malibu Teas is a product that is bio-enhanced and helps to build the soil microbial population. For potted shrubs and roses, there are also bio-enhanced potting soils. In some cases, you might not need to fertilize if you are replacing the container’s soil. You can use teas all year long to boost soil nutrients and the populations of beneficial organisms. Ask our garden experts about teas for fertilizing and soil health. 

Fall is a Good Time to Fertilize 

Many people prefer to fertilize roses and shrubs in the spring, just before the new buds open. We prefer to fertilize one-two months before the shrubs lose their leaves. We do this so that there is plenty of time for the microorganisms can do their jobs before the roses or shrubs need food. That little jolt of food helps shrubs and roses recover from the summer’s heat and primes them for winter. A quality time release, organic fertilizer will prime the soil. 

Different Formulations of Fertilizers

  • Liquid Fertilizers – Generally applied twice over 14 days. Soaks into the ground quickly and is generally more bio-available for shrubs and roses than synthetic or pellet/granule fertilizers. 
  • Pellets – Generally applied once and then watered in. Might require a second application. 
  • Time-release – Applied once per season/year.

The formulation of fertilizers also applies to the variety of fertilizers — for example, a liquid organic fertilizer versus a liquid non-organic or granular fertilizer. 

Note: Water Soluble means liquid. So there is no difference between the term Water Soluble on the label, then there is for Liquid. 

Organic Versus Synthetic

Organic fertilizers include a range of options from fresh or aged manure to fish emulsion. The pros of organic fertilizer are that it is safe to use on most plants as it does not burn the plant the way a synthetic fertilizer can. The other great thing about organic fertilizers is that they help to build and improve the soil. The downside of organic fertilizers is that they are often the top of the price heap. 

Synthetic Fertilizers – are much cheaper than organic fertilizers but more risky to plant health. They can burn the leaves and the roots, and if over-fertilization occurs, they can kill the plant. The plus is that they are convenient. The negatives, in addition to the potential for plant damage, is that they don’t do anything to help your soil in the long-term. 

When to Fertilize

Fall – Use a fertilizer with less nitrogen. You do not want to promote new growth right before a winter frosts hit. In Southern California, you can look closely at the weather and the night low temperatures and decide when to fertilize. 

Generally, you don’t fertilize within 2-weeks of the first frost. The calendar date is not as important as the weather outlook is. For products like Fish Emulsion, many are lower in NPK – 5/1/1, etc. Your goal is to promote root health in fall and if you fertilize in the spring to encourage vegetative growth. 

What Do the Chemicals Do?

  • Nitrogen – promotes new growth and leaf development. Too much nitrogen and the plant grows leaves not buds. It helps with chlorophyll production and plant energy. (Not that important in late fall and winter as the rose or shrub is asleep.)
  • Phosphorous – helps the plant to produce healthy root systems and also helps in bud production. (Great for fall and spring fertilizing as the plant can develop strong roots.)
  • Potassium – A health inducer for plants. It works with the plant’s immune system to promote disease-free plants. It is a great asset to produce vigorous plant growth, including stems, roots, and leaves. (Great for fall and spring fertilizing.)

Fertilizing can be tricky. It is always best to start with a soil sample so you can see the pH and nutrient load of the dirt. If you plant in containers, this is especially true. Our garden experts are always available to help you select the perfect fertilizer for your roses and shrubs and for the rest of your yard too. 

Note: Our inventory changes daily, so call ahead for specialized plants or products. We offer online help and shopping via our website, and you can always drop by one of our five Southern California locations. 


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