Frequently Asked Questions about growing hemp
Everything you need to know from the moment your seeds arrive to your first harvest.
My seeds just arrived — what should I do first?
Before anything else, inspect the packet to confirm the variety and check the seeds look healthy — they should be firm, grey-brown, and not cracked. If the vial included rice desiccant you can remove that from vial and dispose. Store seeds in a cool, dark, dry place (a sealed container in the fridge works well) until you're ready to plant. Seeds stored correctly will remain viable for 1-2 years, sometimes up to 5.
Do I need to notify anyone before I plant?
Yes. Under the 2026 rules you must notify both New Zealand Police and the Ministry for Primary Industries (MPI) before you begin cultivation. Until MPI releases a formal online portal, a simple written email to both agencies is the recommended approach, see blog for template. Include your name, contact details, grow location, intended planting dates, approximate plant numbers, and intended use of the crop. Keep a copy for your records.
When is the best time to plant in New Zealand?
Hemp is a warm-season crop. In most parts of New Zealand, the ideal outdoor planting window is October to November (spring), once soil temperatures are consistently above 10°C and the risk of frost has passed. In warmer northern regions you may be able to plant as early as late September. Avoid planting in autumn — shortening days trigger early flowering and reduce yield.
What kind of soil does hemp need?
Hemp thrives in well-drained, loamy soil with a pH between 6.0 and 7.0. It does not like waterlogged or compacted ground — good drainage is essential to prevent root rot. If your soil is heavy clay, consider raised beds or adding compost to improve structure. A basic soil test before planting will tell you if you need to adjust pH or add nutrients.
Check out organic soil and fertiliser suppliers like Seacliffe Organics for soil amendments, such as worm castings, microbial innoculants and pre-made super soil. Hemp loves Chicken and any ruminant manure also, be careful to semi compost it first and don't over do it.
How do I germinate my seeds?
The simplest method is direct sowing: plant seeds 1–2 cm deep in moist soil, spaced one metre apart depending on your intended use (closer for fibre, wider for seed production). Keep the soil consistently moist but not waterlogged. Germination typically occurs within 5–7 days at soil temperatures of 16–20°C. You can also pre-germinate seeds between damp paper towels indoors before transplanting.
Another tip is to sow your seed into a PB3 bag on the new moon in a greenhouse and raise it until risk of frost has passed then transplant into its final spot. Add aeration such as perlite or fine pumice to your seedling mix to ensure it is not overwatered.
How much water do hemp plants need?
Hemp needs moderate, consistent moisture — especially in the first 6 weeks while roots establish. Water deeply but infrequently, allowing the top few centimetres of soil to dry out between waterings. Once established, hemp is relatively drought-tolerant. Overwatering is one of the most common beginner mistakes and can cause root disease.
Do I need to fertilise my plants?
Hemp is a heavy feeder, particularly for nitrogen during its vegetative growth phase. A balanced slow-release fertiliser at planting, followed by a nitrogen-rich feed during the first 6–8 weeks, will support strong growth. Reduce nitrogen as plants approach flowering in early February and switch to a phosphorus/potassium feed to support seed or flower development. Avoid over-fertilising — it can stress the plant and affect THC levels.
How do I know if my plants are male or female?
Hemp plants show their sex around start of February. Female plants develop small white hair-like pistils at the nodes; male plants produce small pollen sacs. If you're growing for seed, you need both. If you're growing for fibre or flowers only, remove male plants promptly to prevent pollination. Most commercial hemp seed varieties we sell are feminised, meaning 99% of all plants will be female.
How do I know when to harvest?
Harvest timing depends on what you're growing for. For seed, harvest when around 70% of seeds have matured and the lower seeds are firm and grey-brown (typically March–April in NZ). For fibre, harvest at early flowering for the finest quality. For flowers/biomass, harvest when trichomes are milky-white and pistils have turned amber — usually in the first week of April, depending on the variety.
How does hemp know when to flower?
Unless specified, Hemp seeds sold on this site are photoperiod. Photoperiod hemp remains in vegetative growth while receiving long daylight periods, commonly 18 hours of light per day indoors, or long summer days outdoors. Flowering typically starts when light exposure drops to around 12–14 hours of daylight,
with longer uninterrupted darkness periods.
Growing in urban environments, be mindful of artificial lights near your garden, security lights for example. These can stress a plant and make it think the daylight hours are changing so it may flip in and out of vegetative and flowering cycles. Genetics sold on this site are robust and have been stress tested to take small amounts of light interference.
What are the most common mistakes novice growers make?
- Planting too early when soil is still cold
- Overwatering, especially in heavy soils
- Forgetting to notify Police and MPI before planting
- Not testing soil pH before planting
- Planting male and female plants together when only female plants are wanted
- Harvesting too early before seeds or flowers have fully matured
- Incorrect balancing of nutrients. Check ai or web for leaf deficiency issues.
- Planting in a space that doesn't receive plenty of sun.
What if my crop tests above 1% THC?
If your crop exceeds the 1% THC threshold it is no longer classified as hemp under the new rules and may be treated as a controlled drug. This is why starting with quality, low-THC genetics from a reputable NZ breeder is so important. Our cultivars have been specifically selected and tested for stable, compliant THC levels under New Zealand growing conditions.
Where can I get more help?
The best starting points are the Ministry of Health hemp page and the MPI website for notification guidance. You're also welcome to contact us at info@hempseeds.co.nz — we're growers too and happy to help. Good growing.