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Fast Grapefruit Grow Journal

fast grapefruit grow journal
Posted by: Samuel Thomasino Category: Grow Journals Comments: 0

Fast Grapefruit Grow Journal

Fast Grapefruit Strain + Grow Setup Info

Grapefruit is one of the most unique and mesmerising scents on the market and is loved by all types of smokers for its sweet, dank, and acidic grapefruit notes.

This strain, Fast Grapefruit, takes this classic and crosses it over with a specialist fast flowering plant that results in the same Grapefruit we all know and love but with an ultra-fast 6 to 7 week flowering phase making it around two weeks faster than the original strain.

Many smoke reports show that this quicker version is just as potent and beautiful as the original. But don’t just take our word for it, check out the fast grapefruit grow journal below!

fast grapefruit grow stats

For more details, or to purchase these seeds, check out the official strain info on the Dark Wizard Genetics Fast Grapefruit Seeds page

In this grow journal the plant will be grown under these conditions:
Lighting: 500w CFL (2x250w -2 Blue/Veg, 2 Red/Flower) + 120w Led panel halfway through flower
Light Cycle: 18/6 & 12/12
Temperature: 21-25°C
Grow Space: Indoor
Medium: Bio Bizz light mix soil
PH level: 6 – 6.7
Nutrients: Bio Bizz + Mollasses + pk 13/14

Grow room setup:
Tent – Dr 90 (90x90x180cm).
Extraction – 5″ Rvk Fan / 5″ MA Filter.
Intake – Passive, Ducted from outside.
Air Circ – 2pc fans blowing across CFL bulbs and clip-on fan for plants.


fast grapefruit seedlings
All seeds were germinated using the paper towel method and kept in the airing cupboard. All of them cracked and showed their tap root within 24hrs. All the tap roots looked nice and healthy too – all about 5mm long.

I potted them into 3ltr pots to start them off, then in a couple of weeks, I will repot them into 15ltr pots which they’ll stay in throughout the grow. I’ll be using the Bio Bizz nutes – Grow and Bloom. I’ll also be using Mollasses and Pk 13/14 when in flower.

I’ve never used Bio Bizz soil before as I used Canna Terra on my previous grow but I thought whilst I use Bio nutes I’d try their soil. It seems really good quality soil and it came pre-mixed with perlite but I put a little more in too to keep it nice and airy.

The Bio Bizz soil comes with enough nutrients in it for 2 weeks so by then I’ll hopefully repot up into the 15ltr pots.

fast grapefruit seedlings

Fast Grapefruit at 8 days old

Here is a quick update with some pictures of the plants at 8 days old. I slightly watered them tonight (1/2 ltr between the 3) just watering around the edge of the pot to protect the young and fragile root system.

fast grapefruit seedling 8 days old

fast grapefruit seedling 8 days old


Fast Grapefruit at 13 days old

At 13 days old the plants are now into vegetation and are taking full-strength nutrients. Watered all the plants tonight, they all got 500ml of water each at pH 6.75. Still watering around the edges of the pots.
young veg - 13 days

Fast Grapefruit at 17 days old

Fast Grapefruit at 17 days old
Plants are all growing at a steady rate with no issues.

Fast Grapefruit at 21 days old

The plant is well into a vegetative state now and I will consider putting it into flower in around 1 week’s time. Plants are all around 8″ in height and are taking about 1 litre of water each every two days.
Fast Grapefruit at 21 days old


Fast Grapefruit 1 week into flower

The plants are now 1 week into the 12/12 light cycle and just started showing their first white pistons indicating the start of the flowering phase. Plants have also stretched slightly as normal in the first 2 weeks of 12/12. The overall age of plants is 5 weeks.
Fast Grapefruit 1 week flower
Fast Grapefruit 1 week flower

Fast Grapefruit 3 weeks into flower

Fast Grapefruit 3 week flower
Fast Grapefruit 3 week flower
They are now nicely into flower and are quickly building buds. Previously last week there were some plant issues with aphids so I was spraying them all with a home mix of water and chopped tomato leaves that I left to stew overnight. It seems to be doing the trick as there are nowhere near as many as there first were so hopefully with another spray or two I should have kicked the little bleeders out for good. I’ve also bought myself some sticky strips to hang in the tent to try and catch any other critters.

Fast Grapefruit 4 weeks into flower

Pest problems have now been dealt with. Buds continue to build up nicely at week 4 in flower.
Fast Grapefruit 4 week flower

Fast Grapefruit 5 weeks into flower

5 weeks into flower some fan leaves have begun to yellow and fall off due to a deficiency. The suspected issue is that the plant needed a higher level of the base nutrients so feed has now been increased.
Fast Grapefruit 5 week flower

Fast Grapefruit 6 weeks into flower

The yellowing of leaves has now stopped getting worse after slightly increasing the feed. Plants are now 6 weeks into flower and showing signs of an upcoming harvest time. I’m planning on harvesting on the 7th week if possible.
Fast Grapefruit 6 week flower

Fast Grapefruit 7 weeks into flower

After using a microscope there are plenty of amber trichomes now, I feel it is ready to harvest at 7 weeks. I think potentially if I really wanted to I could give it slightly more time but it is perfectly acceptable to harvest today so I will.
Fast Grapefruit 7 week flower
Fast Grapefruit 7 week flower


fast grapefruit drying
fast grapefruit nug
So after 7 days the buds were all dry and the yield was pretty decent considering the 500W CFL lights used and the small space.

How much did Fast Grapefruit yield?

Dry weight is just over 2 ounces per plant and I have begun curing the buds now. Had a little test smoke and it was so sweet and addictive to smoke.

How long did Fast Grapefruit take to flower?

After 7 weeks the plant was ready to harvest. As mentioned before another week wouldn’t have hurt but totally happy with the 7 week period.

How tall will Fast Grapefruit grow?

Plants grew to an average height of 1 metre in height. Didn’t stretch too much during the transition to flower as I kept them nice and warm.

Was Fast Grapefruit easy to grow?

Until the last 3 weeks, I had an easy run, just needed slightly more nutrients in the flower than in my last crop. So I would say it was easy to grow. The pest problem was not the plant’s fault and was dealt with fast enough so it did not cause a problem.

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