Garden Roses: When and How to Fertilize for Best Blooms

Roses are some of the most popular flowers in the world, thanks to their gorgeous, fragrant blooms. However, roses need plenty of nutrients from both soil and fertilizer to produce their best flowers. In this article, we’ll find out when and how to fertilize roses.

When and How Should I Fertilize Roses? Key Takeaways

For optimal flowering each season, start fertilizing roses once they produce their first new leaves in the spring. Apply a dose of slow-release fertilizer. During the season, fertilize roses every month or so using diluted liquid fertilizer. Apply another dose of slow-release fertilizer after the final round of flowers in the fall.

When Should You Fertilize Roses?

Roses are hungry plants that must be fed regularly throughout the growing season. Once the risk of frost has passed, start fertilizing your roses in the spring with a nitrogen-rich fertilizer. Wait until your established roses have produced their first new leaves before you start feeding them.

Newly planted roses should also be fed regularly to help them establish a sound root system. When planting a new rose, add some slow-release fertilizer to the soil. Continue fertilizing every month or so throughout the first season.

Throughout the season, feed your established roses with high-phosphorus fertilizer after each round of blooms finishes. This works best for repeat-blooming roses that can flower multiple times in one season. Roses that only flower once each year should finish blooming in mid-summer.

After the last round of flowers, give roses a dose of slow-release fertilizer to sustain them during fall and winter. Stop feeding roses towards the end of the season, approximately six to eight weeks before your first expected frost date. This helps your rose prepare to enter winter dormancy.

The Role of Fertilizers in Plant Health, Growth, and Development

Plants depend on nutrients within the soil to help fuel strong, healthy growth. These nutrients are usually divided into four main types; structural macronutrients, primary macronutrients, secondary macronutrients, and micronutrients. Once our plants have exhausted the nutrients within the soil, we can replenish these nutrients using fertilizers.

There are three structural macronutrients; carbon (C), hydrogen (H), and oxygen (O). These structural macronutrients are absorbed from air and water through a plant’s leaves and roots. Plants then use these structural macronutrients during photosynthesis to produce glucose. This necessary sugar is then used to manufacture cellulose, the basic building block of all plant tissue.

Plants also need three primary macronutrients; nitrogen (N), phosphorus (P), and potassium (K). When plants use their roots to absorb water from the surrounding soil, they also take in these nutrients. Gardeners use fertilizers to replace these primary macronutrients once plants have used them up.

Nitrogen helps produce bushy foliage, while phosphorus is crucial for flower development. Potassium helps plants circulate water, nutrients, and minerals more efficiently. Plants also absorb secondary macronutrients and minerals such as calcium (Ca), copper (Cu), iron (Fe), magnesium (Mg), and sulfur (S).

Different Types of Fertilizers

Fertilizers are usually divided between organic fertilizers and synthetic fertilizers. These fertilizers are commonly sold either as slow-release granules or liquid feed. Compost, manure, and similar materials can also be used as fertilizer.

Organisms in the soil must break down organic fertilizers before plants can absorb the nutrients. Common types of organic fertilizers include compost, blood meal, bone meal, manure, and worm castings.

Synthetic fertilizers work faster than organic fertilizers because they don’t need to be broken down. Plants can access nutrients from synthetic fertilizers straight away. However, synthetic fertilizers are extremely strong and can damage plants unless they’re heavily diluted.

All fertilizers have an NPK ratio that indicates how much nitrogen, phosphorus, and potassium each dose contains. Different NPK ratios have different effects on plant growth. Nitrogen-rich fertilizers produce lots of bushy foliage, making them ideal for leafy vegetables. However, if you want lots of flowers, use high-phosphorus fertilizers.

Signs That Your Roses Are Lacking Nutrients

Yellowing Leaves

If your rose bush has yellow leaves, it might be lacking nutrients. Check that the soil isn’t waterlogged, as yellowing leaves can also be a symptom of overwatering.

Poor Flower Production

Roses that lack nutrients will struggle to produce big, beautiful flowers. If your roses produce smaller flowers than expected, fertilize them more frequently.

Weak or Straggly Growth

Without enough nutrition, roses won’t produce strong, healthy growth. If the new growth on your rose looks weak, leggy, or limp, it may require more nutrients.

How Often Should You Fertilize Roses?

Repeat-blooming roses should be fertilized throughout the season once each round of flowers finishes. For some cultivars, this means fertilizing established roses every two to four weeks. Potted roses also need to be fertilized regularly throughout the growing season.

Newly planted roses should also be fed frequently throughout their first growing season. After applying some slow-release fertilizer when planting, feed young roses every four weeks or so.

The Best Types of Fertilizer for Roses

Both organic and synthetic fertilizers work well for roses, although organic fertilizers are more beneficial over the long term. When your rose produces its first set of new leaves, apply a nitrogen-rich fertilizer. Once growth has exceeded 4 or 5 inches, switch to a high-phosphorus fertilizer to encourage lots of flowers.

At the start of the growing season, slow-release fertilizers also work well for both established and newly planted roses. Roses like nutrient-rich soils, so work in some compost, bone meal, or well-rotted manure to provide extra nutrition.

You can also use synthetic fertilizers such as Miracle-Gro if you dilute them according to the packet instructions.

How to Apply Fertilizer to Your Roses

When applying slow-release fertilizer granules, simply mix them into the soil when planting a new rose. You can also mix them into the soil around your established roses at the start of the growing season.

When using liquid fertilizers throughout the season, always dilute them according to the packet instructions. Lightly water your roses before and after applying fertilizers. Apply fertilizers at the base of the rose to prevent burning the leaves or flowers.

Key Considerations

Although roses need lots of nutrients to produce their best flowers, applying fertilizer incorrectly can damage them. Here are some things to consider when fertilizing your roses.

Soil Type

Providing your roses with good soil gives them plenty of nutrition between fertilizing. Roses need rich, well-draining soil that still retains some moisture. Loamy soil is best, but roses also like clay or sandy soils. These soils should be amended to provide extra drainage and nutrition, respectively.

Over-Fertilizing

While roses do need lots of nutrients, too much fertilizer is bad for them, especially if you’re using synthetic fertilizers. If your rose starts developing brown or crispy tips on its leaves, you may be applying too much fertilizer. The chemicals and salts within synthetic fertilizers can burn rose flowers and leaves.

About Roses

Roses (Rosa spp.) are deciduous woody perennials from the Rosaceae family that usually grow as shrubs or climbing vines. Most roses are native to Asia, but some species come from Europe, North Africa, and North America.

Roses are usually divided into three main groups; old garden roses, species roses, and modern or hybrid roses. These groups are further divided into other types, such as thornless climbing roses, Floribunda roses, or Polyantha roses.

Many roses have large, colorful flowers with five elegant, blousy petals. Rose flowers can be single, double, or semi-double depending on the exact cultivar. Many roses produce intoxicating musky or heady fragrances. Roses also have woody stems with large thorns and pinnate leaves that have serrated margins.

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When and How to Fertilize Roses FAQs:

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Wrapping Up

Roses need lots of nutrients throughout the growing season, which means they should be fertilized regularly. Once new leaves emerge in the spring, apply a dose of slow-release fertilizer. Then feed your roses with a diluted liquid fertilizer every four weeks throughout the season. Apply a final dose of slow-release fertilizer approximately six to eight weeks before your first expected frost date.

For more, see our in-depth guide on how to make roses last longer in a vase, whether roses will bloom indoors, the best types of edible roses, essential tips for growing potted roses, and 3 easy methods to press roses at home.

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