11 Tips for Longer Lasting Gardenia Blooms

While it is true that Gardenia shrubs have lovely foliage, their glossy green leaves are not the first reason most gardeners add them to the landscape. It is the production of their aromatic blossoms that makes Gardenias such desirable plants to have in the garden.

Gardenia flowers are some of the most coveted both in the garden and in the florist industry. They are stunning in simplicity, their creamy, white, rose-form petals creating a striking contrast against that deep, polished foliage. On warm summer evenings, they release their fragrance into the breeze, and I can think of no more pleasant bouquet.

It is only natural for any owner of a Gardenia shrub to wonder what can be done to increase the number and constitution of flowers produced. Getting your Gardenia to bloom prolifically happens as the result of a few different factors and can be encouraged by several others. Here are some things you can do to maximize the bloom production of your Gardenias.

Water Them

Gardenias need about one inch of water per week. That may not seem like much, and in fact, rainwater is typically enough for established Gardenias. If you find yourself in a time of drought, or no rainfall for 2 weeks or more, it is probably time to give your Gardenia a good long drink.

Gardenias don’t like swampy soil, but they do need the soil to be consistently moist. There are a few factors that can influence how much and how often a gardenia needs to be watered to best produce blooms.

Use Mulch

If you’re running into issues maintaining moisture in your soil, a nice thick layer of mulch will help. Mulch helps the soil retain water, as well as acts as insulation in the winter.

An added bonus if you use pine bark mulch is that you contribute to the acidity of the soil as the pine bark is acidic and breaks down into the soil over time. Mulching in the fall, before the first freeze, will help to protect the roots of your gardenia from the cold weather, setting it up for success in the coming year. A healthy Gardenia is more likely to bloom at its best.

Prune at the Right Time

Gardenias benefit from yearly pruning, but for this white flowering shrub, timing is everything. Gardenias set buds in early fall before they go dormant for the winter. With this in mind, pruning a Gardenia should be done near the end of the summer, after the last of the flowers are spent.

Pruning at the end of summer helps to encourage the formation of new flowers for the following year. It also helps to remove any damaged foliage before the gardenia enters dormancy. Diseased and damaged foliage draws water and nutrients that could be directed to healthier growth.

When pruning your gardenia, use clean, sharp tools. The cleaner the cuts, the faster they will heal. Trim off a few inches from the ends of the branches. It is ok to trim both green and brown wood, but don’t cut back more than 1/3 of the plant. While gardenias can be hard pruned, it will drastically reduce the number of flowers you see in the following year.

Deadhead

Deadheading is technically part of pruning, but it should be done throughout the blooming season rather than at the end. If you’re unfamiliar with the practice, the term deadheading refers to the removal of spent flowers to encourage more flowers to bloom.

Producing flowers requires a lot of energy from the plant, and spent flowers form seeds, which also requires a lot of energy from the plant. By removing the spent blooms, the plant knows to redirect the energy and nutrients from those flowers and seeds into other buds.

Deadheading encourages longer-lasting flowers, as well as potentially triggering greater bud production. This can be done by hand by simply snapping off the spent blooms.

It can also be done with a pair of shears for a neater look. By snipping the stem just above a leaf set, you avoid having bare stems at the ends of your branches.

Get the Exposure Right

Gardenias need to have the right amount of sun, at the right time of day, if you want to maximize flower production. A gardenia that isn’t getting enough light is unlikely to produce many flowers at all. Instead, it will produce pale, and leggy growth.

Conversely, if a gardenia gets too much sun, this can also damage the plant’s ability to produce an optimal amount of blooms. A gardenia that gets too much sun will have leaves that appear bleached and faded, and any blooms produced are likely to turn yellow and have a shortened lifespan.

Gardenias technically need full sun, but the time of day makes a big difference. The afternoon sun tends to be hotter and harsher than the morning sun.

Gardenias should ideally receive 5-6 hours of direct sun, as early in the day as possible. Give your gardenia some shelter from the afternoon sun, if possible, to keep your flowers lasting longer and looking fresh.

Give Them Some Humidity

Gardenias also need moisture in the form of humidity, especially if you want them to produce plenty of flowers. A humidity level of 50% or higher is preferred. This is typically less of a problem for outdoor plants and more of an issue for those kept as houseplants.

If you are growing your gardenia as a houseplant, it will probably need some supplemental humidity. There are a few ways you can achieve this:

1. Place your Gardenia in a bathroom which will help with humidity.
2. Use a humidifier to raise the humidity level around your gardenia.
3. Use a pebble tray beneath your gardenia’s pot.

Fertilize

Gardenias need a lot of nutrients to produce large numbers of flowers. Specifically, gardenias should be fertilized once every month during the spring and summer with a fertilizer made for acid-loving plants.

A fertilizer that contains added iron and copper will go a long way toward helping your gardenia produce plenty of new foliage and lots of robust flowers. These minerals assist with bud development.

Avoid fertilizing in the fall or winter, though. Fertilizing encourages new growth and new growth is softer and more vulnerable to cold. Gardenias are quite frost resistant, but their tender new growth, sadly, is not.

Lower the pH

Gardenias are acid-loving plants. They prefer to be planted in soil with a pH level of 6.5 or lower. The acidity of the soil helps to break down the minerals that gardenias need to grow and bloom. Iron is very important in the growth and production of flowers of gardenia plants.

While most soil is not lacking in Iron, the soil needs to be somewhat acidic in order to make the iron useable to plants.

Soil pH can be easily checked and amending it to be more acidic is generally a simple task if you find that your soil is too alkaline. Some solutions that will help raise the acidity of your soil (lower the pH) are:

1. Elemental Sulfur is an excellent soil acidifier.
2. Iron Sulfate also lowers soil pH, but it requires a large quantity.
3. Use an acidic fertilizer, there are fertilizers made especially for acid-loving plants.
4. Use organic matter such as fallen leaves, compost, and, manure to amend the soil.
5. Acidify soil with common household items.

Use Pickle Juice

This one sounds a bit silly, but the reality is that pickle juice, at least the kind that contains vinegar, will help to acidify soil that is too alkaline. Of course, you could just use white or apple cider vinegar, but what’s the fun in that?

Pickle juice contains a lot of salt, which can dehydrate the roots of your gardenia, so it’s best not to pour the pickle juice directly onto the ground around your plant. Instead, add it to your compost pile and add the compost to the soil seasonally.

Use Epsom Salt

Epsom salt contains magnesium and iron, two nutrients that help the plant grow more robust foliage, and longer-lasting flowers. This household item is beneficial for most plants, so feel free to spread it around liberally in the garden.

This salt is much gentler than the salt added to pickle juice, so it can be either sprinkled directly on the ground around your plants or diluted with water and used to water your plants with.

Try Used Coffee Grounds

Coffee is one thing that will help your gardenias thrive. Coffee grounds are a great source of nitrogen. It also increases the acidity of the soil, which gardenias love. There is no need to splurge on coffee specifically for your gardenias though, they are perfectly happy with your used coffee grounds.

Recycling your coffee grounds by sprinkling them around the base of your gardenias helps to reduce household waste, in addition to giving your garden a nitrogen boost.

Coffee grounds can be added directly to the soil around your plants, or to your compost. They should comprise no more than 15-20% of the total volume of your compost though, as they can interfere with the decomposition process.