Bloom vs Incredible Bulk: Which and When

Bloom and Incredible Bulk both get used in flowering, so growers assume they are two versions of the same thing. They are not. Bloom is the weekly base feed from the start of flowering until harvest. Incredible Bulk is a finisher you add on top of Bloom for the last 4-6 weeks. One does not replace the other, and both work best alongside Microbes.

The short answer

Bloom is your base feed for the whole flowering stage. Incredible Bulk is a finisher you add on top of Bloom for the last 4-6 weeks. They do different jobs.

If you only buy one, buy Bloom. Bloom requires Microbes to perform as designed, and Incredible Bulk is recommended alongside them.

Bloom and Incredible Bulk side by side

	Bloom	Incredible Bulk
Role	Base feed through flowering	Finisher layered on top of Bloom
Phase	From the start of flowering until harvest	Last 4-6 weeks of flowering only
Printed grade	4-0.5-0.5	0.1-10-25
Form	Wettable powder	Micronized powder
Base dose	1/4 Tbsp per gallon	1/4 Tbsp per gallon
Per-gallon range on our feeding chart	1/4 to 1/2 Tbsp	1/4 to 4 Tbsp
How often	Weekly during flowering	Weekly in the finishing window
Sizes (product registry)	8 oz, 1 lb, 3 lb, 20 lb	1 lb, 3 lb, 10 lb, 40 lb
Pairs with Microbes	Required	Recommended

Sizes change as stock changes, so check the product page for what is available today.

Look at the two printed grades. They are close to opposites. Bloom's nitrogen number is the largest of its three, while Incredible Bulk is mostly phosphate and potash with almost no nitrogen. That alone tells you they were not built to stand in for each other.

When each one fits

Bloom is the everyday feed. The label also guarantees calcium, sulfur and several micronutrients, which is part of why it works as a base rather than a one-note booster. You start it when the plant begins to flower and keep it going weekly until harvest.

Incredible Bulk is the finisher. It is built for the late part of flowering, and our product docs say to start it about 4-6 weeks before harvest. It is not for vegetative growth, and it is not for the very start of flowering. Let the plant set flowers on regular Bloom first.

Why not run Bulk the whole way? The grade explains it. Nitrogen mostly drives leaf and shoot growth, and in most flowering crops you want that to taper off late in the cycle. Bulk's low nitrogen suits the finish. Used from the first week of flowering it is the wrong balance, and our docs call that overkill. Bulk's label also does not guarantee the calcium or the micronutrients (boron, copper, iron, manganese, zinc) that Bloom's does.

Microbes sit under both. Bloom requires Microbes to perform as designed. Bulk does not carry that same requirement, but we still recommend running it with Microbes, because it layers on top of a Bloom program that already depends on them.

What to do: three common situations

Flowers (ornamentals, in the ground or in containers)

Start Microbes the day you plant or transplant. Do not wait for soil to settle.
Switch to Bloom when flower buds begin to form, and feed weekly.
If you want a finish, add Incredible Bulk for the last 4-6 weeks before the plants are done flowering. For a plant with no real harvest date, count back from when you expect the display to end, and treat the 4-6 week window as a guide, not a hard line.
Stop Bulk when you begin any flush with plain water. Many growers flush in the final 1-2 weeks, and our docs say to stop Bulk at the start of the flush.

Fruiting vegetables such as tomatoes

You do not need both. Bloom with Microbes is the base flowering program. Bulk is optional.

Tomatoes make this less clean than a plant with one fixed harvest. Many varieties flower and set fruit continuously for months, so "the last 4-6 weeks" has no obvious start. If you do want to use Bulk, pick a point late in your growing season when you want the plant to put its energy into ripening what is already on the vine, and begin there. If you cannot tell where that point is, staying on Bloom is a sound call. We do not publish a tomato-specific Bulk schedule, and we do not promise any change in yield from adding it.

King Krustacean is a separate option for tomatoes and does a different job from Bloom or Bulk. Our product doc lists it as best for vegetables and fruit, tomatoes especially, because of its calcium. Its dose is on the feeding chart.

A plant that is already in bloom

Do not panic, and do not start with Bulk.

If the plant has been on something else, move to Bloom now, with Microbes alongside.
Feed Bloom weekly. You have not missed anything by starting mid-flower.
Add Bulk only once you are inside the last 4-6 weeks before harvest.

If you have already been using only Bulk, add Bloom as the base and keep Bulk as the late-stage layer.

Mixing and dosing

The mix order for our feeds is water first, then Microbes, then the powder. Use the dose on the feeding chart for your crop. One thing we do not publish: a combined per-gallon recipe for running Bloom and Bulk in the same tank. Each product has its own chart dose, so follow each one.

For scale, Incredible Bulk works out to about 8 feedings per ounce at the base dose, where one feeding is one gallon of feed. That is roughly 128 gallons of feed from a 1 lb bag. This figure comes from the product page data, not from weighing a bag, so treat it as an estimate. We do not publish a feedings-per-container figure for Bloom here.

Houseplants

If the plant is a houseplant, do not reach for Incredible Bulk. Kelp It Real is the product we point houseplants to.

Where Growganica fits

For most growers the right setup is Microbes plus Bloom, with Incredible Bulk as an optional finish for crops with a clear harvest window.

Bloom if you are growing anything through flowering and want one base feed.
Incredible Bulk if you already have Bloom going and want a finisher for the last 4-6 weeks.
Microbes with either, and always with Bloom.

If you are growing tomatoes or other continuous bearers and are not sure about a finishing window, Bloom plus Microbes is the base program. Skip Bulk until you know you want it. Browse the full line at Shop All and see how the pieces fit together in The System. Doses by crop are on the feeding schedule.

Frequently Asked Questions

Can I skip Bloom and use only Incredible Bulk?

No. They do different jobs, so one does not replace the other. Bloom is the base feed for the whole flowering stage, and Incredible Bulk is a finisher layered on top for the last 4-6 weeks. Bulk's label also does not guarantee the calcium or the micronutrients (boron, copper, iron, manganese, zinc) that Bloom's does. If you only buy one, buy Bloom.

Which one do I use at the start of flowering?

Bloom, with Microbes alongside. Switch to Bloom when flower buds begin to form and feed weekly. Incredible Bulk is not for the very start of flowering; our docs call it overkill there. Let the plant set flowers on regular Bloom first.

Do I need both for tomatoes?

No. Bloom with Microbes is the base flowering program for tomatoes, and Bulk is optional. Many tomato varieties flower and set fruit continuously, so the last 4-6 weeks has no obvious start. If you cannot tell where that point is, staying on Bloom is a sound call. We do not publish a tomato-specific Bulk schedule, and we do not promise any change in yield from adding it.