The best fertilizers for roses in August and September

Blooming takes a lot of resources from roses. Weakened plants become easy prey for fungi and bacteria and don't survive winter frosts well. Fertilizing in August and September is a key step in properly preparing rose bushes for winter.

Rose needs after flowering and replanting

Roses expend a large amount of nutrients on bud formation, most intensively consuming potassium, phosphorus, boron, zinc, and calcium. By late summer, the soil from which the rose plant draws these nutrients is depleted, so the plant cannot replenish the deficiency on its own; it requires fertilizing.

But this is only one of the goals of care in August and September—to restore the bushes' strength and resilience by restoring the plant's nutrient balance. The second goal is to prepare roses for winter, which involves adjusting the nutritional composition, increasing the value of some elements and limiting the use of others.

Furthermore, late August and early fall are the best times to repot rose bushes. After this procedure, the plants require especially careful care, including nutrition.

Macronutrients

To ensure a successful winter, all shoots on the bush must be woody by the time low temperatures set in. New growth that emerges in late summer will not have time to mature and is highly likely to be damaged by frost, leading to tissue rot. By the time winter protection is removed, the bush may die or, at the very least, be significantly weakened, losing its immunity to fungal and bacterial diseases.

Phosphorus and potassium promote wood maturation. Phosphorus fertilizers have a particularly significant effect—the element's saturation increases the concentration of soluble carbohydrates in plant sap, which is responsible for the lignification of young shoots.

Potassium has a similar effect, increasing the proportion of proteins and carbohydrates in cell sap. It also stimulates the transport of sugars from leaves to other parts of the plant. A high sugar content in intracellular fluid makes plants more resilient to subzero temperatures. A third beneficial property of potassium is its boosting of immunity and endurance, which increases the chances of a successful overwintering.

Roses benefit from a nitrogen deficiency before winter. This isn't about nitrogen starvation—weakened bushes won't survive the harsh winter. However, roses should receive the required dose of nitrogen through fertilizers at the beginning of the growing season; in the second half of summer, this element should be eliminated from the plant's diet. Nitrogen stimulates vegetation, while shoots emerging in late summer don't have time to harden before winter.

This diet is also relevant for replanted bushes. Nitrogen is contraindicated for roses when relocated in the fall, but phosphorus is needed for the development of new roots, which will help the bush establish itself more quickly in its new location before winter approaches. Roses also need potassium at this time, as replanting weakens them, and potassium enhances the plants' adaptability.

Microelements

After flowering, roses need to be given a complex micronutrient fertilizer. However, if the plant is deficient in any micronutrient, targeted supplementation with the appropriate substance is required.

The deficiency can be determined by the appearance of the plants:

Fertilizing in August and September

To restore roses' nutrient reserves in August, it's recommended to use liquid fertilizers—these fertilizers are better absorbed by plants than solids. Alternate watering with nutrient solutions and spraying the bushes. Foliar feeding will help roses recover as quickly as possible, reducing the risk of disease as they weaken.

In the event of an early cold snap, foliar fertilization should be limited to foliar application, as nutrient absorption through the roots is poor in low-heat conditions. Micronutrient deficiencies in plants can be replenished through foliar feeding.

Before applying liquid fertilizer to the roots, rose bushes should be watered with warm water. Spraying should be done in dry, cloudy weather or in the evening, when the sun's rays can no longer scorch the damp rose leaves. However, it is not recommended to apply the fertilizer in the dark, as this will prevent the leaves from drying out overnight, increasing the risk of fungal diseases. The optimal time for foliar feeding is shortly before sunset, when the sun is low.

To saturate the soil with nutrients, you should add mineral preparations in the form of granules or organic matter in solid form, then the plants will be able to gradually absorb nutrients from the soil as needed.

Organic fertilizers after flowering

Roses can be given organic fertilizers after flowering only in August; no organic fertilizers should be added closer to fall. Wood ash is an exception. Organic fertilizers are not suitable for roses after repotting, as the required amount is added to the planting hole.

The most suitable organic fertilizers for the crop:

• Cow manure. Add 5 kg of manure to 5 buckets of water and 1 kg of wood ash. Let the solution sit for a week. Use it diluted for watering: 10 liters of water for every 5 liters of solution.

• Chicken manure. This fertilizer is prepared similarly to cow manure infusion, but requires a lower concentration of 1:20 (if the manure is old, a 1:10 dilution can be used). Before watering, dilute 3 liters of the infusion with 10 liters of water.
• Green infusion. Any weed can be used, but nettle is considered the most effective for providing potassium. Chop the green parts of the plant and fill a bucket 2/3 full. You can add 250 g of wood ash. Fill the bucket to the brim with water and leave it to steep in the sun (preferably) for 7 days. The finished infusion should be diluted with 10 parts water, without straining, if you plan to fertilize the bush. The green infusion is also suitable for spraying; in this case, strain the solution and dilute it with clean water at a ratio of 1:20.

• Ash. To enrich the soil with phosphorus, ash is applied dry, spreading approximately 250 g per square meter. For faster absorption, make a liquid fertilizer. Add 0.5 kg of ash to a liter of hot water and boil for 10-15 minutes. Afterward, let the mixture steep for 24 hours and then dilute it in 10 liters of water. This ash infusion can be used for foliar feeding—it's also a good preventative against fungal and bacterial diseases.
• Yeast. Dissolve 10 grams of dry yeast in a bucket of warm water with 2 tablespoons of sugar. After 2 days, dilute the solution with 5 parts water. Since watering with yeast solution causes the soil to lose potassium, it is recommended to combine this fertilizer with the addition of dry ash.
• Bone meal. Apply dry to the roots of plants. This product is not used for quick plant nutrition; it is recommended for building up phosphorus reserves in the soil.

Organic fertilizers primarily serve to restore the fertility of soil depleted after roses bloom. A good way to provide long-term fertilizer is to spread well-rotted manure around the bushes (on top of the soil, not into it). As it decomposes, the manure will slowly enrich the soil with nutrients. This method is especially beneficial for roses after replanting.

Mineral fertilizers for roses

Unlike organic fertilizers, mineral fertilizers can be given to roses before winter. However, in August, it is recommended to supplement root feeding with organic fertilizers, applying them foliarly.

After replanting, it is recommended to provide roses with potassium through foliar feeding for maximum absorption, and to add phosphorus fertilizers to the soil, including in solid form, for gradual absorption.

For feeding roses it is recommended to use:

• phosphorus – superphosphate (regular or double) and ammonium phosphate;
• potassium - potassium sulfate, potassium nitrate, potassium magnesium sulfate;
• potassium and phosphorus - potassium monophosphate.

The following mixtures are suitable for root feeding of roses during this period:

1. Superphosphate + potassium nitrate. Dissolve 50 g of double superphosphate in a liter of hot water and let sit for 3-4 hours. Strain, dilute with 10 liters of water, and let sit for 24 hours. Add 20 g of potassium nitrate immediately before spraying.
2. Superphosphate + monopotassium phosphate. 25 g of superphosphate should be diluted according to the previous recipe and 15 g of monopotassium phosphate should be added to the resulting solution.
3. Superphosphate + potassium sulfate. Add 30 g of potassium sulfate to the prepared solution of 50 g of superphosphate.

Superphosphate can also be used as a phosphorus supplement in organic fertilizers; the element's content in cow manure and green infusions is insufficient to adequately feed roses after flowering. Add 50-100 g of superphosphate to 10 liters of manure or grass solution. After adding the superphosphate, let the solution sit for at least 24 hours. It can be added to manure infusions at the beginning of preparation; this mixture can be stored for a long time.

Solutions for foliar feeding are prepared according to similar recipes, but in lower concentrations:

• 15 g of superphosphate and 7 g of potassium nitrate;
• 15 g superphosphate and 10 g potassium sulfate;
• 5 g of superphosphate and monopotassium phosphate per 10 liters of water.

Fertilizing plan

After flowering, roses should receive a large dose of potassium and phosphorus, as well as a one-time application of organic fertilizer. The bulk of the plant nutrition should be provided in late summer, with fertilizers applied sparingly in September. Depending on the weather during this period, you can focus on watering with solutions or increase the frequency of spraying.

Approximate feeding schedule:

• Immediately after flowering, rose bushes should be fertilized with organic infusions (cow manure, bird droppings, herbal infusion) or a complex fertilizer (such as "Kemira Universal"). Since it is no longer advisable to apply organic fertilizers in mid-August, natural fertilizers are recommended for roses that finish blooming by the end of July. If rose bloom ends earlier, it is advisable to apply a complex fertilizer immediately afterward, followed by an organic fertilizer in early August.
• At the same time, foliar feeding with micronutrients should be performed. Complex micronutrient fertilizers are suitable, but if any of the elements are deficient, additional spraying with a solution of the required substance is required after 1-2 weeks.

• Two weeks after fertilizing with organic matter (mid-August), roses should be given potassium and phosphorus in the form of watering with a solution of mineral fertilizers.
• A week after applying potassium-phosphorus fertilizer, water with potassium sulfate. An alternative option is to water with an ash solution.
• During August, you should spray the plant once with a superphosphate solution, and two or three times with an ash infusion – this provides potassium and prevents diseases.
• Young plants or those weakened by unfavorable conditions, disease, or repotting should be fertilized with colloidal sulfur after flowering, using foliar application. Timely application also prevents fungal growth. Superphosphate contains up to 10% sulfur, making it doubly beneficial for roses.
• At the beginning of September, you need to do foliar feeding with potassium magnesium sulfate, dissolving 16 grams in 10 liters of water.
• In the first half of September, spraying with potassium sulfate is carried out to stimulate wood ripening.

Fertilizing for micronutrient deficiencies

If the plant didn't receive sufficient nutrition in the spring, it may experience a deficiency of one or more micronutrients after flowering. This deficiency should be addressed immediately using foliar feeding.

Preparing for winter

Preparing roses for winter, in addition to fertilizing, includes:

• autumn watering regime;
• pruning bushes;
• clearing the planting from weeds;
• prevention of fungi and pests.

To prepare rose bushes for winter, they need to receive adequate water in the fall. Avoid allowing the soil to dry out or become overly wet. During dry September, roses should be watered once a week, with 20 liters of water per bush. Deep soil soaking is essential; shallow watering will not saturate the plant.

Later, depending on the weather, watering frequency is reduced or stopped. However, just before the cold weather sets in, one watering—a moisture-replenishing irrigation—will still be necessary. Pour 40 liters of water under the rose bush, then mulch the area around the trunk.

After each watering, loosen the soil to oxygenate the roots. However, this procedure should be stopped in mid-September. Along with loosening the soil, remove weeds to prevent the bushes from competing with them for nutrients and moisture. In the fall, clearing the planting of weeds becomes especially important, as fungal outbreaks are significantly less likely in a clean flowerbed. In temperate regions, roses spend the winter under cover, where thaws create a humid and warm environment, so the risk of rot and fungal infections is high.

Green shoots that haven't yet developed woodiness should be pruned in late September or early October. Diseased and dead branches and leaves should also be removed. It's important that the plant be completely healthy when it's placed under cover; otherwise, there's a risk of finding a bush damaged by fungus in the spring.

Before covering, it is customary to remove all the leaves from the bush to prevent disease, but you should not do this in September, otherwise the roses will have time to begin developing new foliage.

Improper preparation for the winter season is a common cause of rose bush failure. Not only is depletion due to nutritional deficiencies fatal, but over-nutrition can also be fatal for southern plants. The short summers of the temperate climate often prevent roses from depleting their resources for flowering, so if temperatures aren't cool enough, flowering may even occur late in the fall.