Coco coir works ok as a seed starting medium but it isn't a growing medium. And even for seed starting it works best when mixed with other ingredients.

You would not be direct seeding your seeds right into the buckets anyway but using small seed starting containers and a seed starting mix and many of them contain some coir. Then once your plants are transplant size, say 6" tall or so - you would transplant them into the containers where they would grow. You can learn more about all this over on the Growing from Seed forum here.

So you want your buckets/containers filled with a high quality soil-less growing mix rather than coir or soil. The Container Gardening forum here has many discussions about what soil-less mixes work well in containers. They are also a good source of info on what fertilizers to use since container plants need frequent feeding.

Keep in mind that Big Beef is quite a very large indeterminate variety so it needs a really big container, something in the 10 gallon range and Rapunzel is a giant so also needs at least 10 gallons. If by buckets you mean 5 gallon buckets then neither of those varieties are bucket plants.

Dave

Edited to add link to FAQs:

FAQ: how-do-i-start-tomatoes-from-seed

Agree. You can start seeds in a lot of things, sand, DE, peat moss., pine bark fine, etc. Seeds have enough store of nutrients to germinate, grow few leaves and roots to get started. From that point on they would need nutrients. At that point you need a medium with balanced drainage and moisture retention with nutrients. I use a mixture of peat moss, pine bark fine and DE (floor dry) when I pot from cells to 2" pots. And water from bottom so the top is always dry.

Having said that there is more than one way to skin a dead cat.

Sey

I think it's not very good if you top water your containers. It drains real fast, it's better for self watering/hydro systems. Also more expensive than peat based.

The rocks are probably as a mulch and maybe to prevent wind to 'steal' your medium little by little when it dries on top (also maybe to deter birds who have a real liking to go and dig through my containers at least).

i'm growing tomatoes in grow bags filled with a mix of coir, peat moss, and perlite and they are producing very well. this is medium i am reusing from growing baby ginger in last year. fertilizer was added to the mix before it was used for the ginger. no additional fertilizer has been added since.

Randy - you are growing tomato plants with no nutrients, no fertilizer at all? How is that even possible much less successful?

Every plant needs at least the basic nutrients in some form to even survive much less produce and coir, peat and perlite contain none at all.

Dave

So I have to admit I was wrong, my biggest mistake in container growing was to use coconut coir and I'll probably never use them again for that purpose. All coconut coir does is act as a sponge and tie up all the nutrients, because they are not broken down. Also if you allow your container dry out they make your mix gets clumpy with too much air pockets which allow ants to nest. They seem to work fine as seeds starter or hydroponic uses. I have also used them in my worm bins which work very well. Otherwise, if you use them in mixes it's better to use a whole lot of fertilizers or make sure they are well aged (very dark brown, which pretty much none of them are sold that way except for premium products). These days I like best using potting mix + compost and add some slow releasing fertilizers.

I think coconut coir have their benefits if used for correct applications, but somehow I feel there are salesmen out there making a killing fooling people to use these stuff in their soil mixes. Even though they are marketed as more sustainable than peat, I'm not sure about that considering the amount of water used for their production and the cost of shipping across continents.

there is probably still available fertilizer in the mix i'm using. i was going to feed but i got enough toms. its also possible that the roots have gone through the drainage holes in the bags and then into the soil below. anyway i like using coir.

Thanks for the awesome responses! I'm growing these tomatoes in Toronto, ON so I only get like 5 months of summer weather. I don't think that the Rapunzel & Beef Stake tomatoes with have enough time to grow out of a 5 gallon bucket (I could be wrong though). I'm going to try planting them both in buckets and in soil (I'll try to get rid of the grub worms before planting).

I'm getting mix reviews on the coco coir. How come people use them? Here's an example:

https://www.youtube.com/watch?v=bRyBKWqLzI8&ab_channel=KCETSoCalConnected

Thanks everyone :)

Hmmm... I didn't click any of the links, so just commenting on the responses here, I think there could be some confusion. Coir is a perfectly fine soil amendment, but it is not something that should take center stage in any mix. One should learn and understand its characteristics, strengths, and weaknesses, then use it where it will serve an intended purpose.

"I'm going to try planting them both in buckets and in soil (I'll try to get rid of the grub worms before planting)."

The question of using coir aside for a minute, you definitely don't want to use soil in any container much less one that small. That it compacts, drains poorly, causes root rot, and increases the chances of damp-off and other fungal diseases is common knowledge with experienced container growers.

A 5 month growing season isn't a short growing season when it comes to tomatoes and is fairly standard for much of the northern US as well. Even late season varieties are only 80-90 DTM and you have 150 growing days. You gain even more time by using transplants or growing your own transplants 6-8 weeks prior to planting out date as most do.

So as I said and others confirmed, coir is a soil amendment, not a growing medium despite what some YouTube video may claim. There are sources of info and then there are sources of accurate info. It is up to you to determine which sources are valid or not.

The video you linked to is about hydroponics, a totally different method of gardening that has nothing to do with what most tomato growers do or what you have described you want to do. Using coir in hydroponics can work because the plants aren't growing in it but in the liquid nutrient solution it is flooded with. All it does is support the roots in the solution. In hydroponic gardening the plants would grow just as well in wool cubes, foam blocks, or the plastic net slings that many hydro growers use.

Dave

Ive been researching coir a lot recently. And from my findings and results ive found coco is actually a great growing medium, especially in using hydroponics in which you can use 100% coir or coir/pearlite. Its basically a ph balanced peat substitute that lasts longer. As long as the coir has been given plenty of magnesium and calcium it wont tie up any nutrients. Its a perfect additive to organic potting mixes as its a great host medium for fungi and beneficial bacteria. Which even in containers you can have thriving populations. Whats great about it is that it holds onto moisture but still allows 30% air flow porosity giving the roots plenty of oxygen.

It works well as long as you use it the right way. If growing in straight coir make sure you have good support for the pla t. Also use of hydroponic nutrients is going to be a must. I have had good results making potting mix with it, and it seems to last 3 to4 days longer between waterings than the peat moss mix .

agree with digdirt based on experience. Even as a growing medium its not as great as peat. it does work well as a top up to discourage fungal growth though - again based on experience.

Simon, Im from north of Toronto. I've had my tomatoes (one being a costoluto) in large (tree sappling) containers as soon as the weather warmed up in late spring because my backyard wasn't ready. Initially I had problems due to lack of nutrients in the soil. I'll admit I hadn't done much to amend the soil and just simply used black earth. Normally I would mix in composted manure. So to remedy the poor growth I saw, I used tomato fertilizer spikes and within a short time, the plants flourished and Ive now an overabundance of tomatoes.

To answer the question on coconut coir - treat it like its sand. Its great for seeds to get started on but poor in providing nutrients. As mentioned in my earlier response, I've used it to top up growing seedlings as a preventative of Damp (fungus). Otherwise mix it with your existing soil to help create drainage.

Ianna