9 Cannabis Germination and Seedling Problems and How to Fix Them

9 Germination and Seedling Issues and How to Fix Them

Once you open your packet of seeds, you will have three options for germination methods. They are to use a glass of water, dinner plates with moist tissue paper, or germinate directly into the growing medium. Below covers some of the issues that can arise and how to solve them!

The Seeds Won't Sink

When using a cup of water to germinate cannabis seeds, you will find that during the first 12-24 hours, the seeds will float on the top of the water. If you give the cup a gentle swirl, the seeds will sink to the bottom of the glass, and within 36-48 hours, you will notice a taproot. Sometimes, however, seeds can remain at the surface and won’t sink or show signs of germinating.

How to Fix: Based on my experience, seeds that do not sink after a day or so are not viable and should be thrown out. This does not mean that all seeds that float are nonviable, so I would recommend trying to germinate the seeds using tissue paper instead if the seeds are floating after 24 hours.

The Taproot Is Mushy

When using the paper towel and dinner plate method, you can have great success with seeds displaying long and fuzzy taproots within 72 hours. There may be times when the taproot seems soft and mushy, and when transplanting into soil, it breaks apart. Anytime I have ever germinated a mushy seedling taproot, it did not sprout out of the soil.

How to Fix: High humidity can cause seedlings to become fragile. I would recommend keeping the paper towels moist but not dripping wet. Germinating seeds need lots of fresh air, so keep a close eye on how wet the tissue paper becomes.

Seeds Don't Sprout

I think we have all been there when you check the pots after 5 days of patiently waiting, and after digging down, you notice the seed has not taken or attempted to grow. This can be a frustrating and expensive process, depending on what genetics you are using.

How to Fix: The answer to solving this issue is to make sure that your growing environment is optimal for seedling growth and development. pH levels also need to be within the correct zone, so this means 6.0 - 7.0 for soil and 5.5 - 6.5 for hydro. Beneficial bacteria and fungi will help stimulate root growth and help restore depleted soil.

Curling Taproot

The taproot of a cannabis seed acts like an anchor, providing stability for vegetative growth and establishing a prolific root system made from fibrous roots. There will be a time when you notice that your seedling is growing very small compared to other seedlings. In the past, when plucking seedlings like this out of the soil, I saw the tap root had curled upwards.

How to Fix: The way I have solved this problem in the past is to use a matchstick and create a firm 2cm-deep tunnel into the soil. Then, using tweezers, I make sure the tip of the root is gently placed into the bottom of the 2cm hole. There will be nowhere for the seed to grow but down, and I eliminate this problem. Cannabis roots are able to grow down and outwards and establish a prolific root mass.

The Seedlings Are Too Small

Cannabis seedlings can grow quickly and evolve into bushy plants with a thick, solid stem and side branches. There will be times when your seedlings look too small and do not seem to be getting any bigger. Your soil is good, the nutrients are good, and the lighting is good. 

How to Fix: When this happens, it will usually be the result of a pH imbalance causing a nutrient lockout. Another reason could be that the seedling has become stunted due to heat stress, overfertilization, or a soil pathogen. To combat this, keep the temperature as close to 24 degrees Celsius as possible, follow the nutrient mixing guidelines when feeding, and use trichoderma to protect the roots.

The Foliage Is Drying Out

Cannabis plants transpire water by sucking it up from the roots and distributing it to the rest of the foliage. Seedlings are much more sensitive to their environment and grow slowly according to their root mass. If the few leaves on your seedlings appear dry, crispy, or have lost their vigour, then it sounds like the airflow and temperature are too high. 

How to Fix: Wind burn is a result of dry wind constantly blowing at a plant, causing it to transpire and dry out. Cannabis seedlings only require a gentle breeze created by a small oscillating fan on a low setting. Providing seedlings with a gentle air current will promote thicker stem growth and healthier plants.

Seed Shell Is Stuck

This is more common with OG Kush strains. Normally, a sprouting seedling will shoot out of the soil and discard the seed shell. Anyone who has ever grown true OG genetics knows the seed cap will remain on the top of the seedling, keeping it tightly stood upwards above the soil enclosed in the shell despite having a well developed stem.

How to Fix: You must be very careful and take a pair of tweezers and very gently pry on the seed shell. Take your time, and once the shell loosens, you can remove the shell from the plant, exposing it to light and air.

Weak and Lanky Stems

Cannabis seedlings can end up growing tall, lanky and be prone to toppling over the side of their pot. There are several reasons why seedlings can excessively stretch, ranging from low light intensity, light being too far away, the pot being too small, overcrowding, overfertilization, and high temperatures.

How to Fix: I find that seedlings thrive under LED or CFL blue light and develop very short internodal spacing and a compact, tight growth structure. To resolve tall and thin seedling growth, keep your grow light 12 inches above the seeds, monitor temperature and humidity, and use a thin gardening cane and gardening wire to support the stem and prevent the seedling from drooping.

The Seedling Has Fallen Over

I have entered grow rooms in the past and seen growers let their seedlings stretch so tall that they toppled over the side of the pots. It was like an LST on a 2-week-old seedling, and whilst they were growing just fine, they were bent over at a 90-degree angle; it was not ideal, and the seedling area looked very untidy and overgrown.

How to Fix: First, stop the seedlings from stretching in the first place by checking light intensity and distance from the canopy. Also be prepared to repot the seedlings into bigger pots to encourage a compact and bushy growth structure and stability. Anytime a seedling topples over and creates a kink in the stem, use a thin cane and wire to tie and support the seedling to keep it fixed upright.