Gardening with Gary

Gardening Advice from an Expert

Gardenias

Q. I have a gardenia bush that was beautiful the first 2 years, but didn't grow much. This third year it still hasn't grown much and has lost almost all of it's leaves - it still, however, has tons of blooms. Any suggestions as to what is going on here? I am in Florida. Should I try and move it at this point? Can I trim it back now?

A. This is a familiar problem. I want you to do several things.

First, let the plant bloom so you can enjoy all the wonderfully fragrant flowers, as after what you do, you may not be see them for a while. There is no need to shock the shrub by pruning off the blossoms, as this is Nature's purpose, to procreate, and that is why the plant flowers, to produce seed and generate more gardenias for the future!

Second, after the flowering, trim all the branches back to healthy swollen buds, which are where the new vegetative stems will arise. Take off any weak, spindly and dead growth. Do not be afraid to cut if back severely. I do not know how tall it is now, but even back to 2 1/2 to 3' would be OK.

Then, dig around it in a circle and lift it out with as much of the root ball as possible. Take it to another area of the garden, where it receives only half day sun, out of the harsh PM sun rays. Protection from above is a bonus. Add peat moss and decomposed leaf mold or compost to lower the soil pH.

Water in very slowly and deeply. Do not feed until the plant starts to show signs of bud break. Then, give it an acid fertilizer. I recommend MirAcid for gardenias. Follow the label's directions.

Let me know how the bush responds in a couple months, and best of luck!

Q. How do I care for my gardenias?

A. I hope you are growing the plant outdoors in a mild climate. I have no info. That is where gardenias do the best. Other areas where it is cool, have severe winters, or indoors where it is hot and dry, the plant does not thrive and actually ends up dead!

Give it an area where it gets good morning sun and is protected by the harsh PM sun. Do not attempt to grow in total shade. Pick an area where it will be cool when the days are quite warm. Mulch around it to keep the roots near the surface moist and protected from drying out. Water well, have a garden bed enriched with organic material, well-drained and spaded, so that the roots will grow easily and have air pockets for breathing.

Give the plant monthly a fertilizer made for acid-loving plants. MirAcid is a very well-known one. Follow the label directions carefully.

If it gets very warm and the plant is suffering, mist the foliage whenever you can to raise the humidity. Give it good space away from other plants and do not dig around its root system. Pick off flowers when they brown and discard into a compost pile or the garbage.

Watch for mealybug, white fly and aphids. These are their common predators. I hope this helps you grow a happy gardenia!

Q. Why are the buds on my 4 month old potted gardenia Veitchii turning brown and falling off even when I give it plenty of water and monthly acid based fertilizer?

A. I have two ideas here and both may be the reason.

First, a four-month old plant is very young and a gardenia needs time to mature to reach an adult state where it will flower and carry forth with bearing seeds. Nature is similar in plants as animals. Maturity is needed to procreate the form. A young plant is trying out its prowess and producing flowers, but is told that it needs time to establish itself in its environment before it can set seed. Flowers are merely Nature's way of luring insects to pollinate and the end result are seeds.

Quite importantly, I do not know where you live nor what your weather has been like. Gardenias need good warmth, early light or indirect, not harsh, not very hot, and certainly not dry. yes, you are watering it but what about the water in the air, the humidity? If it drops, the gardenia is very susceptible and will drop buds overnight.

Misting daily will raise the humidity as will placing the pot on a saucer filled with gravel and water. When days are particularly dry, protect the plant, even if it means moving it to a cooler part of the garden until the temperatures lower. I have found that gardenias bloom best earlier in the season before the temperatures rise and the humidity drops.

Keep giving it good amounts of water in the AM and the acid fertilizer. Care for it, and next year you will be rewarded with more flowers that stay on the branches.

Q. I live in zone 7 (central VA). I bought a gardenia from a discount store last year. I potted it and have kept it indoors. It is starting to get overgrown for the pot. Can I transplant it outside into my garden? I have read some of your other answers and understand the plant needs acid pH and not too severe winters. Our winters usually are mild, however some years we do get snow and below freezing temps. I would love to have a gardenia blooming in my yard, but I don't want to kill it either. What do you suggest?

A. This is a hard call. Some gardenia varieties are more hardy than others and may survive in your zone 7. It is definitely best to plant the shrubs up near a building or under a large tree to provide a warmer winter condition.

You can grow the plants indoors and place out in the spring and enjoy all summer long until your frost arrives. Or, you can risk planting them outside in a sheltered area. Fertilize with MirAcid to lower the pH and water well all summer long, as any periods of drought will lead to severe leaf edge and tip burn.

I found a forum list discussing hardiness of gardenias. Here are portions:

Try:

'Griffiths Select'
Shooting Star'
'Pixie Queen'

The Virginia Research Station in Norfolk, VA (of the Extension Service) developed a cold hardy gardenia a few years ago. It should be ready for public sales by now. It is possibly called 'Chuck Hayes'

Found an article at: http://users.visi.net/~cwt/chuk-hay.html

It said an exceptionally hardy gardenia was found in Chuck Hayes' nursery, crossed with a double variety, and propagated with the help of the Virginia Beach Research Station. 'Chuck Hayes' is 3 to 5 degrees hardier than standard varieties.

http://forums.gardenweb.com/forums/load/shrubs/msg011350146401.html

LM writes~
I recently received two Gardenias (gardenia veitchii) in plastic pots. These plants are small now and I have kept them inside. They have only had a couple of blooms on them since I got them, about a month ago. The "care" instructions that came with the plants state they like "High, bright light window, porch or patio". I would like to plant these outside and wonder if this is a different variety of Gardenia that only grown in pots, and not suitable for outdoors. If they can be planted outside, when is the best time to transplant them and about how large will they eventually grow?

A. They are a compact hybrid which grows outdoors better than inside. No gardenias are ever really that happy inside, unless in a greenhouse or atrium. Home humidity is too low and when flower buds form, they drop off before opening. But, they can be ground outdoors on patios and near buildings for protection in heavy ceramic pots which compliment their crawling growth habit.

"Veitchii" is a compact, mounding grower that gets 3 to 4 1/2 feet high, very well suited for limited spaces. It blooms from May to November and at times when there is unseasonably warm weather.

"Veitchii Improved" is taller than quot;Veitchii" and can reach 5 feet. It produces larger and more blooms over all. Both are hardy only in Zones 8-11. They run about $27 per gallon container.

Gardenias do best where there is warmth. They will take the full sun along the coast, but will need bright filtered light in hotter inland areas or morning sun and afternoon shade. Plant in soil that drains fast but does retain moisture. Use plenty of peat moss. If your existing soil is heavy clay, you will need to remove about 1/2 to 3/4 and replace with a peat moss mixture.

Plant on the high side and avoid crowding with other plants where they will be competing for root space. Mulch plants rather than cultivating around the base.
Keep soil moist, but where existing plants are growing in a heavy clay soil, infrequent deep soaking is much better than frequent shallow watering. It is always a good practice to water plants deeply and less often. Leach salts out of the soil by using a slow drip overnight with a hose once a month.

Gardenias will respond very well to regular fertilizing. Feed every 4 weeks year round with an acid-loving plant food [MirAcid]. If your plant begins to get yellow or very pale green leaves, it will need to be treated for chlorosis (iron deficiency). Use an Iron sulfate or Iron chelate product.

On leggy older plants, cut back 1/3 of foliage just before their Spring growth spurt around March 1st. Prune anytime lightly for shape, but remember to prune after a flush of blooms so you will not miss out on any of those fragrant flowers.

Kay writes~ My favorite flower is the gardenia and I have 2 small ones growing now in pots on my porch, cannot put them in the ground as I am renting the land and anything I put in the ground has to stay should I move away. I live in the Dallas area and was wondering how I can take good care of them, I want many blooms. Someone told me they need acid fertilizer.

Gardenias make wonderful potted plants on patios, decks, porches, and balconies. The main concern is the watering. You must not allow them to go dry or they will drop their leaves. Low humidity will also cause defoliation. You probably have good humidity throughout the year. Keep them in large pots with good drainage with lots of peat moss and perlite in the potting mix to enrich and lighten. A two-inch layer of broken pottery in the bottom of the pot allows water to stay there but not rot roots. Place them in deep saucers but do not allow to sit in water longer than overnight, again due to root rot. Acidic fertilizers are the best to use. Read the labels. Azalea, Rhododendron and citrus are often mentioned or the phrase "For Acid-loving Plants." Do not allow to heat up during the hottest time of the day. Keep protected but not in the total shade.

Rita writes~ I have several Gardenia plants in the yard. I want to get the seeds from them to grow more. Is this possible and if so, how?

A. Seed production followed by germination and growing to a blooming size plant takes years. Stem cuttings are the better practice and even they should be grafted onto a hardy root stock. It is most practical to buy young Gardenia plants at a nursery unless you do not mind waiting for many years for flowers to appear. Cultivars of Gardenia jasminoides can be propagated by cuttings or grafting. In climates which are not moderate, one should restrict to "own root" because plants grafted on Gardenia thunbergia rootstock are not hardy in outdoor planting areas at temperatures below 28 F. Cuttings can be taken any time during the year, but are most successful in June, July, and August. Tip or midsection cuttings with wood 6-8 weeks old should be cut 4-5" long with at least 2 sets of leaves. Cuttings can be taken at or between nodes as they root from the cut end. Leaf removal is undesirable because it results in a longer rooting period. Rooting of cuttings is best under continuous or intermittent mist, or in a closed-case propagating device. Rooting media should be a 50/50 combination of clean, sharp builders' sand and peat moss; or a 50/50 combination of peat moss and perlite. Propagation should be by grafting scion from a desired cultivar to a seedling rootstock of Gardenia thunbergia. Rootstock seedlings, however, are difficult to obtain. If collecting seed yourself, simply sow the seeds from the berry in flats or pots containing a 50/50 combination of peat moss and perlite or 50/50 combination of peat moss and sand. Seeds germinate slowly and erratically. Seedlings should be removed when they form their second true leaf. By waiting until they produce their second true leaf you may increase their survival rate by 20%. When seedling rootstocks are approximately 6" tall and pencil thickness in stem diameter, they are ready to be grafted. Don't graft too low on the plant because the mature plant's branches may droop to the ground. As a result, the branches may root and may become infested with root knot nematodes. Pruning or grafting high prevents the problem.

Assistance from University of Florida Cooperative Extension, with information and illustrations on grafting: http://edis.ifas.ufl.edu/BODY_MG336

Angela writes~
I recently acquired a gardenia plant and I live in Washington State which, as I'm sure you know, isn't exactly ideal for growing gardenias. It's currently December and the plant is in bud. A couple of the buds have begun to open slightly since I acquired the plant a week ago. I keep the plant in the north/east window during the day and rotate it a few times to get light as other locations are not an option. With the heat on the house is usually at 68F, but I figure since the plant is near a window perhaps that does lower the temperature a bit. Please outline a care schedule and requirements the plant might need while in this stage and in others. I've looked online and found plenty of information specifying what I should do regularly in certain months, but it's very difficult to apply that here since it is budding now versus in summer or spring. I do have some Miracid fertilizer, but am unsure when to use it and how often at this stage.

A. Indoor plants, especially ones which may have been forced prior to arrival in a home, will bloom at various odd times of the year. Care of this plant does not vary by season. Your practices are sound but keep an eye on the amount of cold temperature the plant receives through the window pane as drafts cause bud drop and do not allow room to drop below 65F. Give it good indirect light as much as possible with no direct sun between 10am and 2pm and water only when the soil surface is dry to the touch [do not overwater as this can cause root rot and bloom burst.] Give it a full soaking each time and empty the bottom saucer and discard. Apply the Miracid once every two weeks at one teaspoon per gallon water. Remove brown leaves, flowers and buds to prevent spread of disease.

Cynthia writes~
I live in Las Cruces, NM. and have a very large gardenia bush, nearly 8' across and 5' high in my front courtyard. The courtyard is partially shaded by latticework but gets a lot of sun nonetheless. Since I have lived here in the last 2 years, it bloomed heavily but this year I only got about 5 blooms. Most disappointing! The bush is beginning to overgrow the patio as well. I am originally from the Midwest where gardenias only grew in hothouse pots so I have no idea how to care for this gorgeous and fragrant plant. Should I prune it, how and when? Food, what type, when and how much? Or leave it alone until the tremendous heat of the summer is over?

A. High humidity is essential to gardenia [Cape Jasmine, Gardenia jasminoides] care. The soil should be kept uniformly moist, but do not overwater. A loose, well-drained organic soil is recommended. Fertilize monthly between April and November with an acid fertilizer. Gardenias tend to leach trace elements from the soil. Patterned yellowing of the leaves may indicate manganese or magnesium deficiencies which can be corrected by the addition of appropriate trace elements, or using an enriched fertilizer. They should be fertilized in Spring with a complete fertilizer. The lower leaves on the branches yellow and fall as new growth is made at the head of the branches, so it is important to prune back at least every second year after flowering to prevent the plant from becoming leggy. Check regularly for insects and other pests such as aphids, mealybugs, spider mites, thrips and scales. Do not mist the foliage as it can lead to leaf spot fungus or powdery mildew. The most irritating problem encountered with gardenias is bud drop, when flower buds abort just before blooming. Common causes include low humidity, overwatering, under-watering, insufficient light high temperatures, rapid temperature fluctuations, cold drafts or change in plant locations. Plants that do not set flower buds may be experiencing too much warmth.

Start preparing your beds in the fall for next year. Till the garden soil especially if there is sod to be turned under. This will reduce erosion, expose heavy soils to frost, kill exposed insects, aid the decay of organic matter and enable earlier planting. Work in any organic matter when tilling. Do this every fall so that the garden takes less time to prepare every year. It is best to wait until spring to fertilize, but the addition of granular lime in the fall will help condition the soil for spring planting. Never work wet soil, especially clay. This may ruin the soil structure for the entire season and end up with solid, sun-baked clods. Tell if the soil is dry enough to till by picking up a handful of soil and if you can squeeze water from it, it is too wet. If the soil compresses into a ball and stays that way, it needs more drying time. If it is dry enough to crumble in your hand, it is ready to be worked. Be sure to remove any dead plants and debris from all your gardens as soon as the plants die down. Leaving them over winter is inviting insects and disease to take up residence. In the perennial bed, cut back all plants for neatness and disease control. Leave 3-4" of stems to hold snow for winter protection and cover tender perennials as soon as the ground starts to freeze.