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Organic Super Soil Amendments | Definitive Guide To All-Natural Plant Food

The right organic soil amendments will breathe new life into tired super soil both during a grow and when you recycle your substrate. By replenishing nutrients when your plants need them most, you can ensure your organic grow results in a huge yield of crystal-coated buds with superior potency.

Contents:

By design, organic super soil has everything your cannabis plant needs to thrive. However, even the best mix may need to be replenished or amended from time to time. This is especially true when you start off with a store-bought mix, cultivate heavy-feeders, or reuse your soil.

Here’s a list of organic soil amendments that will keep your plants happy and productive, as well as those to avoid:

ORGANIC SOIL AMENDMENTS TO USE

1. WORM CASTINGS

With minimal effort and expense, a worm farm can provide an unlimited source of worm castings for your garden. You can also buy worm castings by the bag at most greenhouses and nurseries. Worm castings release nitrogen into the soil faster than virtually any other organic soil amendment. They also add healthy bacteria and a wide variety of micronutrients.

2. CRUSTACEAN MEAL

Made from ground-up shells from crabs, shrimp, and other sea creatures, crustacean meal is naturally high in nitrogen, calcium, phosphorus, and chitin. It’s a slow-release amendment, and it has a bonus feature: The chitin supports microbes that kill harmful nematodes that would damage roots if not kept in check.

3. BAT GUANO

This natural amendment has more nitrogen and phosphorus than any other natural substance you can add to your soil. Bat guano will also add a diverse community of bacteria and microbes to your plant’s root zone and support consistent plant growth.

4. BONE MEAL

This blend of ground beef bones is a great source of phosphorus, as long as you keep your pH level under 7. Outdoor cannabis farmers will need to fence off their plants if they use bone meal. Some animals are so attracted to bone meal’s aroma that they’ll dig up your garden to get at what their nose tells them is buried there.

5. BLOOD MEAL

Blood meal is similar to bone meal, except it’s made from dried cattle blood. This amendment is very high in nitrogen and can burn your plants if you use too much. It will also lower the soil’s pH level. Blood meal is thought to repel deer, squirrels, and moles, but it can attract dogs and other carnivores. Think carefully before you use it in an outdoor garden.

6. CHICKEN MANURE

Chicken manure is rich in nitrogen and phosphorus, but it’s really strong. It’s considered a “hot” fertiliser that can burn your plants if it hasn’t been properly treated and allowed to mellow for a period of time. Use this soil amendment with caution. Rabbit manure is a good substitute if you own a bunny or know someone who does; it’s plentiful, cleaner, and not nearly as hot.

7. ROCK DUST

Rock dust is exactly what it sounds like: crushed rock. It’s a slow-release source of phosphorus. If you recycle your soil, you’ll only need to add it every couple of years. Rock dust requires a pH level of around 7 to work.

8. KELP MEAL

Made from dried seaweed, kelp meal adds potassium to the soil, as well as over 60 essential elements and minerals, to help support the microbes in your soil. It’s thought to increase sweetness, boost flavour, and enhance colours—things that most cannabis growers desire.

9. COMPOST

Compost isn’t exclusive to the realm of organic weed growers. All farmers love this “black gold”. It’s generally made by layering soil, leaves, and household food waste, so it’s as good as what you put into it. If you’re using it for potassium, make sure you include banana peels and fruit rinds. Eggshells add calcium, and all compost contains beneficial microbes. Always make sure the compost is fully broken down and decomposed before adding it to your plants; it should look like rich, black soil when it’s ready to be used.

10. COMPOST TEA

If your plants look like they need a quick pick-me-up, try a compost tea. You can make this by aerating a mix of clean water and a small amount of compost. The air activates the microbes and causes them to multiply at a rapid rate. Within a few days, you’ll have a nutrient-rich compost tea that you can use as a liquid soil amendment throughout your grow.

11. WOOD ASH

Wood ash is a great source of potassium and lime, as well as many trace elements that cannabis needs to thrive. However, you should use this soil amendment sparingly or combine it with compost. It’s known to quickly raise the soil’s pH level to the point where it could lock out other nutrients.

12. MYCORRHIZAL FUNGI

Without beneficial fungi, organically grown cannabis plants will struggle to thrive. These microorganisms create a bridge in the root zone that helps plants absorb nutrients and water. They also protect the roots from damage by shielding them from harmful microbes. To add mycorrhizae to your soil, use a tube of inoculant.

13. PERLITE AND VERMICULITE

Cannabis likes air in its root zone. That’s why it’s important not to overwater or let your plants sit in standing water. It’s almost as bad to let the soil get too dry. Using perlite and/or vermiculite as soil amendments can help. Perlite is made from volcanic glass; it’s white, hard, and porous. Vermiculite is made from mica; it’s scaly, lamellar, and pale brown in colour. Both are very light in weight compared to their volume, and do a great job controlling moisture and aerating the soil. You can use one or both as a soil amendment.

14. GARDEN LIME

Also known as sweet lime or dolomite, garden lime is made from limestone. It contains a significant amount of calcium and magnesium. Although it actually raises pH, this type of lime is often used as a buffer to keep pH levels stable and prevent fluctuations. When liming your plants, always use dolomite lime and not agricultural or hydrated lime.

15. EPSOM SALTS

Magnesium sulfate, commonly known as Epsom salts, is a natural source of magnesium and sulphur that plants can readily use. Always use pure magnesium sulfate purchased from a pharmacy, and not a bath product that’s had oils or scent added to it. You can amend your soil by adding the crystals when you water your plants or by mixing them into a foliar spray.

16. AZOMITE

Derived from volcanic material, Azomite replenishes the soil with more than 60 water-soluble trace minerals. Those are the kind that can get washed away when you water your plants. This amendment can raise pH level, so it’s another one to use sparingly.

ORGANIC SUPER SOIL (NUTRIENTS) 1. WORM CASTINGS 2. CRUSTA- CEAN MEAL 3. BAT GUANO
NITROGEN (N) X X
PHOSPHOROUS (P) X X
POTASSIUM (K)
MAGNESIUM (Mg) X X
CALCIUM (Ca) X
BORON (B)
ORGANIC SUPER SOIL (NUTRIENTS) 4. BONE MEAL 5. BLOOD MEAL 6. CHICKEN MANURE
NITROGEN (N) X X
PHOSPHOROUS (P) X
POTASSIUM (K)
MAGNESIUM (Mg)
CALCIUM (Ca) X
BORON (B)
ORGANIC SUPER SOIL (NUTRIENTS) 7. ROCK DUST 8. KELP MEAL 9. COMPOST
NITROGEN (N) X X
PHOSPHOROUS (P) X
POTASSIUM (K)
MAGNESIUM (Mg)
CALCIUM (Ca)
BORON (B) X
ORGANIC SUPER SOIL (NUTRIENTS) 11. WOOD ASH 12. MYCOR- RHIZAL FUNGI 14. GARDEN LIME
NITROGEN (N) X
PHOSPHOROUS (P) X
POTASSIUM (K)
MAGNESIUM (Mg)
CALCIUM (Ca) X X
BORON (B)
ORGANIC SUPER SOIL (NUTRIENTS) 15. EPSOM SALTS 16. AZOMITE 17. GREEN- SAND
NITROGEN (N) X
PHOSPHOROUS (P) X
POTASSIUM (K)
MAGNESIUM (Mg) X
CALCIUM (Ca)
BORON (B)
ORGANIC SUPER SOIL (NUTRIENTS) 19. MULCH
NITROGEN (N) X
PHOSPHOROUS (P) X
POTASSIUM (K)
MAGNESIUM (Mg)
CALCIUM (Ca) X
BORON (B)
ORGANIC SUPER SOIL AMENDAMENTS (SPECIFIC NUTRIENTS)
NITROGEN (N) PHOSPHOROUS (P) POTASSIUM (K) MAGNESSIUM (Ma) CALCIUM (Ca) BORON (B)
1. WORM CASTINGS X X X X
2. CRUSTACEAN MEAL X X X
3. BAT GUANO X
4. BONE MEAL X X
5. BLOOD MEAL X X
6. CHICKEN MANURE X
7. ROCK DUST X
8. KELP MEAL X
9. COMPOST X X
11. WOOD ASH X
12. MYCORRHIZAL FUNGI X X
14. GARDEN LIME X
15. EPSOM SALTS X
16. AZOMITE X X X
17. GREENSAND X
19. MULCH X X X X

17. GREENSAND

Greensand looks like it sounds: like greenish sand. Its chemical name is glauconite, and it’s a rich source of potassium. It also contains calcium, magnesium, iron, phosphorous, and 30 or so trace minerals that help plants grow. Greensand also improves the quality of the soil to better control moisture levels. In sandy soil, it decreases the drainage rate. In clay soils, it does the opposite, loosening the soil so it drains faster. Greensand is slow to break down and release its nutrient content, so you only have to add it to soil every few years.

18. HUMIC ACID AND FULVIC ACID

Use these two soil amendments together for best results. Humic acid helps the roots absorb nutrients more effectively, while fulvic acid makes the nutrients more bioavailable to the individual plant cells. Together, these two acids help the plant make the most of the available nutrients while minimising deficiencies.

19. MULCH

Mulch serves two purposes; it helps your soil retain moisture, and microbes like to eat it. Don’t mix this into your soil. Add a few centimetres of straw, compost, or wood chips over the surface of the soil. Replenish it monthly. Compost doubles as a top dressing and will gradually release nutrients as you water your plants.

SOIL AMENDMENTS TO AVOID

Urea is a component in urine; it’s what the kidneys make when they remove nitrogen from the body. You can also buy pure urea. It’s a cheap source of nitrogen, but not a great choice if you’re growing cannabis. Urea changes quickly to ammonium, which transforms the nitrogen your plants can use into toxic nitrites that plants don’t use or need. Next, the ammonium will turn into ammonia, which will evaporate and release a nasty smell.

SAWDUST

Sawdust contains nitrogen, but it contains even more carbon (50x more). This combination will lock out all nitrogen and starve your plants. You would have to allow the sawdust to age nearly 3 years to give the carbon enough time to decompose to the point it wouldn’t cause nutrient lockout. Don’t be tempted to mix sawdust into your soil to aerate it or increase its ability to hold moisture.

NON-COMPOSTED LEAVES

If you amend your soil with non-composted leaves, they’ll become fodder for harmful bacteria as they decompose. As these bacteria proliferate, they will compete with your plants for nitrogen—and they usually win.

A FINAL WORD ON SOIL AMENDMENTS

By nurturing your organic substrate with the right soil amendments at the correct intervals, you can grow healthy, profit-yielding cannabis plants with big, resinous buds. When you enjoy the fruits of your labour, you’ll also take comfort in knowing they weren’t exposed to any harmful chemicals or toxic pesticides.

However, it can be easy to overdo it and burn your plants—even if your amendments are 100% natural and organic. Take it easy with richer add-ins until you see how your garden reacts. It’s always easier to add than subtract from the soil. Soon, you’ll be able to anticipate what your plants need, giving them exactly the right amendments at exactly the right time.

Even the best super soil requires replenishment from time to time. In this helpful guide, we'll teach you what to use and what to avoid.

How to Re-Amend Soil for Reuse

How to Re-Amend Soil for Reuse

Over the last few months, we’ve had quite a few people asking how to go about reusing the same soil that they’ve been using. This is especially true for those growing within containers, as well as specifically for cannabis. So, we figured we’d make a post because we love to recycle our soil and use it over and over again too!

Why re-amend your soil for reuse?

To start, if you’re growing a number of plants and continually transplant them to larger pots, you may find yourself with a giant stack of nearly nutrient-less soil sitting in those smaller pots.

Even for those simply growing veggies, we often go through a few pot sizes before placing them into the garden plot or final container it will call it’s forever home. We know we do, as we like to start seeds indoors early on and always take extra time to harden them off. By us, the wind gusts can reach up to 50 mph, so extra time hardening off is pretty much a necessity if you want your little guys to survive the strong winds.

Each time the pot size increases, we’re left with an empty pot and little nutrients left in it. Maybe some of you already tried to plant in the same pot only to discover nothing really grew well in them. For this reason, re-amending your soil to use over and over again is key in not only cutting waste but saving a butt-load of money too.

What about re-amending plots or raised beds?

For those looking to re-amend large garden plots or raised beds, the steps we explain below will work as well. It’s all about how much soil you have and how nutrient-rich you need it to be for your next crop to be planted and thrive.

Typically with plots and raised beds, you want to ensure you fully re-amend the soil at least three weeks prior to planting anything in it. This will allow time for the area to cook the nutrients into the soil.

If you’re looking to speed up the process, take a black tarp and place it over the area you re-amended. This will trap the heat in and allow for the newly amended soil to cook at a much faster rate than if just left open to natural conditions.

So, how do I re-amend my soil for reuse?

For those that are emptying small pots and containers, go grab a tarp to dump the soil on. Once you have all of the soil you’d like to re-amend dumped on to the tarp, it’s time to add the missing nutrients back into the soil.

For those re-amending a plot or raised bed, you do not need to move the dirt! Simply spread the missing ingredients on top of the area. Then lightly overturn the area to mix the amendments into the top six inches of soil or so. There is no need to go much deeper than that, as you will disturb microbes and organisms living down there. Therefore doing more harm than good.

Alright, now it’s time to add the goodies to your soil, wherever it may be, in a plot or on a

tarp. Depending on the amount of soil you are re-amending, the below inputs will vary.

For our example, we are going to break it all the way down to a single 15-gallon pot, as well as what it would look like re-amending three-yards of soil.

To start, go ahead and gather the following amendments in the below quantities:

Single 15-Gallon Pot

Roughly 3-Yards of Soil

Optional Inputs:
½ to 1 Cup Gypsum 30 to 40 Cups Gypsum
⅓ to 1 Cup Bokashi 20 to 25 Cups Bokashi
½ to 1 Cup Alfalfa Meal 30 to 40 Cups Alfalfa Meal

Now, please note that you may find yourself needing more or less of the above nutrients. Additionally, you may also find yourself needing to add even more amendments to the soil, such as the optional ones mentioned above.

Grower Tip: Pay attention to the plants you had in the soil prior to needing to re-amend. They will clue you in on what is missing in your soil and what needs to be added.

Have some pots that could use some nutrients after a few runs? Learn how to reamend your soil to support the next plants you use in the newly mixed soil.