Cultivation

Average price last year was 10 euro per kilo organic flower and leaves with good CBD ratio - dried to below 20% moisture content.

Soils

Hemp will thrive in a wide variety of soils but we advise as follows:

• Hemp prefers a loamy open soil with good moisture holding capacity.

• Hemp will grow in sandy soils but drought is a risk and organic matter is important.

• Avoid heavy clay and poorly aerated or compacted soils.

• Avoid permanently saturated soils or those prone to prolonged summer flooding.

Season

Hemp can generally be sown from May onwards. The key consideration is soil temperature. The absolute minimum temperature for sowing is 10° C but ideally wait until soils reach 15° C. Typically sowing in the 2nd half of May and early in June is ideal. Early sowing can be harvested from August onwards. Frost will accelerate the drying of the crop and bring the season to an earlier end. All harvest possibilities cease towards the end of October/early November.

Cultivars

Hemp is an annual crop and the preferred variety for most Irish farmers is Finola which is ideal for the Irish Climate. The Finola variety is a short season variety with good CBD content. The time from sowing to flowering is short and Finola is a ‘dwarf’ variety when compared to other crop varieties. It is also a heavy seed bearing variety and it is possible to harvest the seed with a combine harvester.

Virtually all the other varieties are longer season varieties and take much longer to flower and seed. These varieties are not practical for seed currently as they cannot be combined. However there are suppliers developing equipment to harvest hemp tops from these varieties.

Varieties such as Felina, Fedora, Futura, Santica and Kompolti are biomass varieties but also have good CBD content. These varieties require earlier sowing. Because they take longer to flower the window for hemp top harvesting is narrower. For example, Kompolti has a high CBD content but it takes 150 days to mature which means that harvesting will be taking place in October. Of course they will all produce a heavy crop of biomass: so, if the goal is biomass production then these are ideal varieties.

Nutrition

Fertile soils will yield good crops of hemp. Check for lime and apply as required. For organic nutrition, use a quality rock dust as either a soil or compost amendment. Rock dusts will provide long term stable nutrition of P, K and trace minerals. For N a combination of strategies includes:

• Compost made using the Indore method.

• Nitrogen fixing companion plants such as clover, peas or vetch.

• Green manures in rotation.

• Returning canes to field to increase organic matter.

• Using biochar as a soil amendment and the encouragement of azotobacter.

There is no need to over fertilise hemp as this can cause the crop to lodge and also increases the likelihood of moulds in the flower heads.

Cultivation

Hemp is a tillage crop with a short growing cycle. The crop can easily be incorporated into other farming activities either as part of a tillage rotation or as a break where ley ground is being re-seeded and a cash break crop is taken. Hemp requires the normal tillage operations of ploughing, harrowing, levelling and sowing. Hemp germination benefits from rolling immediately after sowing. Hemp has thrived in both the wettest and driest of Irish summers. However, drought is a risk, so try to avoid sowing into dry ground and sow after rain or when rain is expected to get a good strike.

Weed Control

As a vigorous crop hemp can generally out-compete weeds. This is particularly true of the taller varieties however the Finola variety is slightly more vulnerable to weed competition.

Earlier sowing can suffer more from weed competition. If it is the case that there is a high weed seed population in the ground to be sown, it is better to allow weed seeds to germinate and establish a stale seed bed. Sowings in late May and June are less likely to suffer from weed competition.

Denser sowing will also close the canopy and compete with weeds. Fat hen and redshank are the strongest competitors. If hemp is grown as a horticulture row crop as opposed to a grain crop a wide range of hoeing equipment is available. This is well worth considering as hemp can be a lucrative crop if infrastructure is in place.

Disease

Hemp is not susceptible to terminal disease causing organisms. However, grey mould (botrytis), can be a common problem in hemp flower heads towards the end of the growing cycle particularly in a damp, wet autumn. Avoid over fertilisation particularly with high N Manures.

Harvesting

This is the greatest challenge and depends greatly on the end use and planting area. For growers new to hemp it is strongly advised to start small. It is quite feasible to hand pick hemp on a small scale.

Areas from 1 to 5 acres can be hand harvested if help is available. If you plan to hand harvest consider a lower sowing density and wider row spacing. This reduces the seed cost and establishes larger individual plants which can be more rapidly harvested by hand. Experienced pickers can pick 30 kgs per hour if equipped with picking bags. Hand picking provides the highest quality material. It also facilitates gradual drying in open airy covered spaces.

• Like any other green crop hemp will ensile quickly if not processed immediately.

Finger bars will easily cut hemp and there are systems available to cut and convey hemp tops to a trailer. People with an engineering background may well be able to construct their own equipment.

Farm Infrastructure

If you are planning to become a full time hemp farmer please consider the following infrastructural assets which will allow you to enter the market with security:

• Drying Floors. There is a good demand for dried hemp tops which will fetch €5-15/kg at 15% MC and depending on CBD levels. Hemp can be easily dried as the stiff cane allows the air to pass.

• Heating Equipment. Some farms may already have cheap or economical sources of heat which can be used to dry biomass or have the capacity to put this in place.

• Tillage Equipment. Many farms will have this equipment in place. However farmers exiting the beef/dairy industry may want to consider investing in tillage equipment.