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I have a hedge of yesterday, today, tomorrow plants which hardly have any flowers. All trees are over 1m tall, bushy, healthy and beautiful. But no flowers!

This is in Brisbane, Queenslands.I went to my local garden shop to get an advise and they laugh at me and asked what I did for them. They were surprise as these trees usually produce lots of flowers.

They gave me couple of bloom boosters which I tried in last 3-4 months, but still no luck.

They have little morning sun and lots of afternoon sun. Does anyone know any trick to get them produce flowers?

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CharithJ
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    Welcome! Your tags say houseplants (meaning indoors) but hedge implies outdoor - could you please clarify? Also, how old is the hedge, is the lack of flowers new or has it always been like that? What’s your care routine (water, fertile, trimming, etc.)? Could we get a few photos, ideally both showing the whole plant or hedge and a close up? Roughly where in the world are you, especially what’s the season at your location right now? – Stephie Jul 08 '22 at 03:58
  • Do they get much afternoon sun? – Brōtsyorfuzthrāx Jul 08 '22 at 05:27
  • @Stephie: Sorry it's outdoor hedge. It always been like that. I do not trim much, do little bit. Used bloom booster since last few months and usually yes I guesse general flower fertilizers. I am from Brisbane, QLD, Australia. Thank you – CharithJ Jul 08 '22 at 05:29
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    @Brōtsyorfuzthrāx: Yes they get more outdoor sun than morning sun. – CharithJ Jul 08 '22 at 05:30
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    Can you add a photo or two please – Bamboo Jul 08 '22 at 11:19
  • @Bamboo I have added some photos. Thank you. – CharithJ Jul 12 '22 at 06:40
  • Can you just clarify the following please 1. this hedge does not get morning sun, only afternoon sun? 2. How long have you had this hedge? 3. Has it ever had any flower at all, even just one? When, what time of year, precisely, have you cut it back? – Bamboo Jul 13 '22 at 13:31
  • @Bamboo : 1. Very little morning sun, it get sun from 12 to 5pm. 2. Three years old hedge 3. Every plant has had couple of flowers before. They had flowers when I bought small plants 3 years ago. I haven't cut it much. Just trimmed to top in last spring about 9 months ago. – CharithJ Jul 14 '22 at 00:19

2 Answers2

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I can think of two possible reasons:

Fertilizer balance

General "grow" fertilizers usually contain more N than P and K, often double (ie. 2-1-1) or more. Relative abundance of Nitrogen and scarcity of Phosphorus and Potassium might lead plants to favor the development of green parts (leaves, stems) over flowers.

Check the NPK proportions of your fertilizer. If you want flowers, try to favor P and K over N. So-called "bloom boosters" are usually just regular fertilizers with a more balanced NPK composition, ie. closer to 1-1-1 or even higher P-K than N, ie. 1-2-2.

Most houseplant fertilizers usually come with a lot of micronutrients on top of NPK. I wouldn't worry about them unless your garden's dirt is really poor. They're usually important only for potted plants where the available soil is very limited.

Soil acidity

Soil pH is important for nutrient uptake. Brunfelsia plants like acidic soils (below 6). Your soil might be too alkaline for their liking. Most plants can survive and grow to some extent in a wide variety of soil conditions if forced to, but they only really thrive in their favorite setting.

Your only real option here is to get a soil pH tester, they are inexpensive and you can rule out whether this is the actual problem. If you find that you need to lower your soil pH, there are lots of commercially available and homemade options, each with its own pros and cons.

PS: I don't know the local climate, but even if it's almost tropical, as long as there's some noticeable seasonal variation in temperature and humidity I wouldn't expect plants to bloom in the middle of the "winter" even if it's comfortably warm, or in the hottest of the "summer" even if it's not scorching hot.

willyjoker
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  • Thank you, what about lack of morning sun and having them very close to each other as a hedge? Can that causes some issues? – CharithJ Jul 13 '22 at 09:36
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    Morning sun is the same sun as afternoon sun. Afternoon sun is deemed more dangerous for shadow and semi-shadow plants because after the hottest hours of the day, the air is hotter and drier than in the morning, and sensitive plants are more likely to get sunburnt leaves. This won't be an issue for Brunfelsia as they tolerate full sun; if anything, they'll be happy to have some shade at all. – willyjoker Jul 13 '22 at 11:14
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    Regarding hedge formation: plants rearrange themselves, push and "fight" each other, if necessary, to get enough sunlight. If you plant a small tree below another larger tree, it will try to escape the large tree's shade and grow more in the opposite direction. Bushes will fill the available gaps and grow more upwards and sidewards rather than against each other. There are lots of pictures of flower-ridden Brunfelsia hedges in Google, so I wouldn't worry about that. – willyjoker Jul 13 '22 at 11:24
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I fully understand the surprise in the nursery: Brunfelsia pauciflora is known as an easy grower also in cooler climate outside optimal conditions.

The lack of flowers does not mean you did anything wrong. Light conditions seems to be perfect. They prefer lots of light but not too much direct sunlight at noon. They are healthy and has a dense growth indicating a satisfactory soil.

Bloom boosters

As user willyjoker partly covered, in N-P-K (Nitrogen-Phosphorus-Kalium) fertilizers a high value of N is said to stimulate growth of leaves, P flowers and fruits, and K the roots.

In case of P deficiency adding Phosphorus in a useful form to the soil could be the solution.

But even in the case of P sufficiency a very high value of N can make the plants prioritize growth of leaves on the cost of flowers. In such case a bloom booster is good for nothing. The dark green colour and dense growth indicates a high value of N in the soil.

High P in fertilizers (bloom boosters) is often obtained by adding Calcium Phosphate known for making the soil alkaline, and that is not helpful for plants preferring acid soil.

Water

If you did anything wrong, it is my guess it is related to watering. These plants need plenty of water, and you should consider carefully how you do it: If you water frequent but only enough to make the upper two inches of soil wet, then you stimulates your hedge to produce roots in this upper layer, which quickly dries out during the day.

Try to dig a small hole after watering to check where the water goes and where the hedge produces roots!

Using the same amount of water per week you may find that it is better to use two times the amount of water every second day og even three times every third day.

For a professional solution look for a dripper hose and an automatic valve, and program it for irrigation in the early morning. You can also use a piece of drainage pipe and place it vertical to bring the water to a lower level.

Observe:

Dry soil conditions also can induce phosphorus deficiency in young plants.

From table 3 in this source you will also learn that you should prefer manure from cattle or chickens if using an organic fertilizer.

So what do you do now?

Success in the garden is often related to patience. You could have the soiled tested and you could replace the soil for at least one plant.

Or you can be patient: Sooner or later any extraordinary value of N has been consumed, and with proper irrigation, sparse use of a balanced fertilizer and good care, your hedge will be covered by flowers.

Gyrfalcon
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  • Thank you!. Actually initially I we have put a good layer of cow manure. That helped it growing very quickly. Probably they still have heaps of N. But can it completely suppress flowers? Is there anything we can do for this now? We do not water them regularly. I'll do it for a few months and see. Thanks again for your detailed answer! – CharithJ Jul 18 '22 at 00:27
  • Cow manure is identical to cattle manure and this is ideal according to the provided link. As I understand your question occasionally you have flowers just not as plentiful as expected, and yes this is common for bushes growing fast. From the photos I get the impression that watering can be quite difficult. Try the simple trick with a vertical drainage pipe for a single plant - remember no soaking. If it works, expect flowers within a month. – Gyrfalcon Jul 18 '22 at 01:27
  • I usually see 1-2 flower each tree per year. Almost nothing :) So just to get confirmed. You suggest heaps of water that goes further down the ground can help? Sorry, just out of curiosity may I know how that will help for the flowers please? Thank you. – CharithJ Jul 19 '22 at 03:46
  • The point is to bring the water to a level where it does not vaporize fast and stimulate the growth of roots here. The reason to supply more water even your hedge does not look thirsty is a) to reduce the concentration of N, and b) the citation "Dry soil conditions also can induce phosphorus deficiency in young plants." - The problem the garden shop tried to solve using bloom boosters. This attempt failed because the level of P in the soil was already high because of the wise choice of cow manure. So the citation suggests if adding P does not help, then try water. – Gyrfalcon Jul 19 '22 at 10:13