Feeding and mulching Gardenias are fed during the growing season from spring to autumn with a complete fertiliser such as Seasol plus Nutrients Roses & Flowers. Water it in well after application. Plants also benefit from liquid feed such as PowerFeed PRO SERIES for Roses & Flowers during the growing season.
Gardenias use a lot of nutrients to produce so many glorious blossoms. Feed your shrubs by applying an acidic, slow-release fertilizer such as an azalea or camellia fertilizer. For the organic gardener, blood meal, fish emulsion or bone meal work well.
Another benefit of using seaweed fertiliser over time is it acidifies and adds iron to the soil, which is great news if you are growing acid and iron hungry plants like gardenias, camellias, azaleas and rhododendrons. It's great on native plants as well.
Fertilising Gardenias
Every 2-3 months from spring to autumn feed with a dose of cow manure and a bit of Certified Organic fertiliser if your soil is particularly poor. For really strong, healthy growth and large blooms we also recommend fortnightly applications of OCP eco-aminogro and OCP eco-seaweed.
The yellowing is caused by a lack of magnesium. We suggest feeding with Tui Enrich Rose, Camellia, Azalea & Gardenia controlled release fertiliser in early spring and late summer, and applying Tui Organic Seaweed Plant Tonic regularly. Epsom salts will also help when there is a lack of magnesium.
Young gardenia leaves turning yellow is likely from low iron. All can be fixed by giving your gardenia a dose of an acidic nitrogen fertilizer containing micronutrients. Once your gardenia leaves are green again, use the fertilizer twice a month from early spring to late summer.
If your Gardenia's leaves turn yellow and drop, aside from the normal aging process of its leaves, this may be caused by any of these reasons: Over-watering or under-watering: Gardenias need at least 1 inch of rain (or equivalent watering) each week. Keep the soil consistently damp but not soggy.
Because gardenias need all three essential macro-nutrients (nitrogen, phosphorus, potassium) and also a good dose of micro-nutrients such as iron and manganese, you should feed them with an organic fertiliser such as Dynamic Lifter. Do this every two to three months from spring through to autumn.
Gardenias, along with roses, palms and podocarpus, need lots of magnesium. When the nutrient is in short supply, the older leaves turn yellow. Give the plant a boost (and maybe return some green to yellow leaves) by applying magnesium sulfate or Epsom salts.
Fertilize Gardenias every 2-4 weeks during their growing season (March to October) with a dilute fertilizer for acid-loving plants. Do not fertilize from November to February. Cut off the faded Gardenia flowers, just below the leaf node, to encourage continuous blooming.
Though vinegar can be fatal to many common plants, others, like rhododendrons, hydrangeas and gardenias, thrive on acidity which makes a bit of vinegar the best pick-me-up. Combine one cup of plain white vinegar with a gallon of water and use the next time you water these plants to see some amazing results.
Are Coffee Grounds Good for Gardenias? Don't worry about adding more coffee grounds to your gardenia soil; these flowers absolutely love coffee. In addition to being an excellent source of nitrogen, the acid in coffee lowers the pH of the surrounding soil, stimulating the roots of acid-loving plants such as gardenias.
It affects a range of plants including gardenias, rhododendrons, azaleas, camellias, roses and citrus. The solution is to get some Epsom salts. Take half a litre of water, and put in half a teaspoon of Epsom salts, then shake and stir. Either water it on plants or you can foliar spray it.
Osmocote is one of the most popular and well-respected fertilizer brands and when it comes to gardenia fertilizers you can't go wrong with this plant food. What you'll love about this product is that it is easy for beginner gardenia gardeners. All you need to do is apply it once every 6 months.
To revive your dying gardenias, remove them from the soil, amend the soil, replant them, and make sure that you water them correctly this time. You should prune your gardenias to help them grow bushy. To help drain water quickly from your gardenia pots, put stones in the pot before placing the soil or potting mix.
Gardenias prefer well-drained, acidic soil with a pH of less than 6.0. Soil with an improper pH may be the reason when there are no blooms on gardenias. Extreme weather– Temperature extremes, either too hot or too cold, can also prevent blooming or cause buds to drop.
Leaves that yellow in the spring may be a symptom of iron deficiency. Consider leaving them on the plant rather than cutting them, as cutting may also remove flower buds. Instead, fertilize your gardenia with an iron-rich fertilizer.
Adding Epsom salts to soil that already has sufficient magnesium can actually harm your soil and plants, such as by inhibiting calcium uptake. Spraying Epsom salt solutions on plant leaves can cause leaf scorch. Excess magnesium can increase mineral contamination in water that percolates through soil.
Low on Magnesium
If your gardenia needs magnesium, this will cause the leaves to turn yellow. You can remedy this with a fertilizer high in magnesium, or you can add some Epsom salts to your soil. Mix one teaspoon to one gallon of water and apply every two to four weeks.
Spray frequently with water, repeating as needed, focusing on new growth. Gardenias can also be sprayed with insecticidal soap or horticultural oil to control aphids. Insecticidal soap or horticultural oil must be sprayed onto the aphids to be effective. Repeat spray three times at 5 to 7-day intervals.
3 - Get Rid of Aphids with Neem Oil
Neem oil is a natural, plant-based insecticide that can be used to control aphids on plants. Here's how to use it: Mix 2-3 teaspoons of neem oil with 1 cup of water in a spray bottle. Add a few drops of dish soap to help the mixture adhere to the plant.
We typically prune gardenias after they bloom. The flower buds are already present on the plant now. Pruning before blooming removes flower buds and reduces blooming.
Outside, gardenia is best grown in a pot so it can be moved under cover in winter to protect from frosts or winds. In areas with favourable conditions year-round, plant gardenia in a raised bed or in the ground.
Prune out diseased tissue, rake up and destroy fallen leaves, and apply a fresh layer of mulch beneath the plants. If needed, apply fungicides as a preventative against powdery mildew. Fungicides are most effective against powdery mildew when used early in the disease development process.
Gardenias perform best when they receive intense morning light and shade from the hot afternoon sun. Sun exposure is necessary for proper flower bud development – with too little sun plants will produce leggy growth and few flowers. On the other hand, too much sun can cause blooms to fade quickly.