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The Best Soil to Grow Hemp: Everything You Need to Know

As with any crop, the soil you grow your plants in can make the difference between having a bumper harvest and a total bust. Thankfully, having the best soil to grow hemp in has a lot more to do with knowing what to add to your soil than starting with perfect soil.

If you’re a farmer looking to add industrial hemp into your crop rotation, you’re in luck when it comes to establishing the best soil to grow hemp. Overall, hemp’s needs aren’t that different from a lot of vegetable crops.

In many ways, you can approach your soil for industrial hemp like you would for corn, tomatoes, and garlic.

Basic Needs for Hemp Soil

Though hemp is often touted as having a resilience that will allow it to grow anywhere, that’s simply not the case. And, even if it could grow anywhere, there would, of course, be environments where it thrived instead of survived.

Your hemp crop will produce the best results if grown on loose, well-aerated loam soil. You’ll want to ensure that the soil also has high fertility and an abundance of organic matter. Additionally, the soil for your hemp crops should be slightly alkaline. Ideally, it will have a pH level of between 7 and 7.5 — it must be above 6.

If you don’t have access to well-aerated loam soil, tiled, or well-drained clay soils, will suffice. Sandy soils can also produce quality hemp if you can manage to balance your checkbook when dealing with the increased costs of irrigation and fertilization that come with using such soil.

Word of caution: planting your hemp in poorly structured soils or poorly drained clay will most likely fail — it’s not worth the risk.

A Basic Fertility Program for Hemp

Even if you have the best soil to grow hemp, you’ll need to establish a fertility program. Keeping your soil happy is the same as keeping your plants happy. By paying close attention to your nitrogen, phosphorus, potassium, calcium, sulfur, and boron levels, you will be able to ensure your industrial hemp crop is getting the nutrients it needs.

Though there are currently ballpark numbers and plenty of theories floating around about creating the best soil for growing hemp, there is also a lot of experimentation underway.

“We’ve seen hemp’s fertilizer needs parallel corn, but I have to emphasize three years of data is not solid,” explains Joseph Sisk, a Kentucky hemp farmer. “Murray State University and the University of Kentucky are both looking hot and heavy at fertilizer use. Who knows the right amount? Nobody, yet”.

Nitrogen for Hemp Soil

Like many crops, hemp needs lots of nitrogen. The amount of nitrogen you’ll want to add to your field before planting will be hugely impacted by the results of your soil samples. However, under ideal circumstances, Pennsylvania State University Cooperative Extension recommends about 150 pounds of nitrogen for a crop expected to produce 1,500 pounds of yield.

Another way of thinking about it is adding about 100 pounds of nitrogen per acre — 120 pounds if your soil is particularly nitrogen deficient.

Phosphorus for Hemp Soil

One misconception about growing hemp for CBD oil is that there needs to be an excessive amount of phosphorus because a healthy harvest relies on producing lots of flowers. Hemp does need more potassium than most crops, but that’s no reason to go over the top.

A standard amount of phosphorus per acre, about 50 pounds, would be just fine. However, if you want to bump that up to 80 pounds per acre, it’ll be even better for your crops.

Sulfur for Hemp Soil

While the amount of sulfur you need is tiny compared to the amount of nitrogen needed to get the max yield from your hemp crops, it’s still an essential addition to your soil.

Sulfur is used in several protein enzymes that regulate nitrogen fixation and photosynthesis. Because of this, having a non-limiting amount of sulfur in your soil at the right time is vital for maximizing your yield.

Similar to garlic, your hemp crop will need about 20 pounds of sulfate sulfur per acre.

Boron for Hemp Soil

Unlike beets or brassica, boron isn’t so crucial for hemp. Nonetheless, you can do a mid-season leaf analysis to see if you have any issues. Given that boron levels walk a fine line between deficiency and toxicity, it’s best to avoid prophylactically applying it.

Adding Fertilizer to Hemp Soil

Though you can get away with doing all your fertilizing ahead of planting industrial hemp, setting up a system to fertilize and irrigate at the same time is preferable.

In this case, you can rely heavily on fish emulsion and kelp extract. You’ll get some nitrogen from the fish emulsion and plenty of potassium, micronutrients, and amino acids from the kelp extract.

The amount you’ll want to use per acre will depend on the exact product you’re using. But, no matter how much is required, you’ll want to add fertilizer to your crops about once a week.

Don’t Go Crazy with Compost

Compost is a great way to introduce life into your soil, as well as build soil structure and organic matter. However, compost often adds extremely high levels of potassium and salt. Your potassium application via composting — or however you want to do it — is going to be dependent on your cation exchange capacity.

The higher your cation exchange capacity, the more potassium you need.

The primary issue you might run into with putting too much compost on your field is that the potassium can block your hemp’s access to the calcium it needs.

Whoever you’re getting your compost from should be able to provide a detailed analysis of their product. Ask for that, then base your application rate on that information.

A Common Mistake in Hemp Soil Preparation

One mistake you’ll want to avoid when preparing your soil is adding phosphorous at the same time as your calcium.

When you do this, you end up liming, which reduces the acidity of your soil. Given that hemp has a sweet spot with regards to the soil being slightly acidic, you don’t want to accidentally make it more base.

Additionally, when you add your phosphorous and calcium at the same time, they can lock together, becoming calcium phosphate, which is super tightly bound and more difficult for your hemp crops to access.

Final Thoughts: The Best Soil to Grow Hemp

The basics for what soil you’ll need in order to maximize your industrial hemp yield is pretty straight forward. However, even with the best soil to grow hemp, you’ll want to do everything possible to ensure that it remains nutrient rich in a way that is most beneficial for your crops.

Though much is still unknown with regards to the best fertilizer programs for hemp, following a similar system to that used for corn is a good rule of thumb. However, no matter what fertilizer program you settle on, having the best seeds and clones to plant in your soil is essential.

Talk to the experts at Bonafide Seeds about what plants will allow you to tap into the rapidly growing, lucrative hemp industry.

Fallon Hanley

View posts by Fallon Hanley
Fallon boasts 15 years of experience in growing and breeding cannabis and hemp, and managing grows.