You really have to watch pests, or all your efforts could result in little or nothing in return. Mites and Aphids are the worst; whiteflies, caterpillar and fungi are the ones to watch out for long term. Pyrethrum bombs can start you with a clean slate in the room, and then homemade or commercial soap sprays will do most of the rest. When bringing in hemp plants from outside, pyrethrum every broad leaf top and bottom and the soil too. Then watch them closely for a week or two, and soap down any remaining bug life you find from eggs being hatched. This should do the trick for a month or two, long enough it won’t be an issue before harvesting.
Fungus is another obstacle in the path of a successful growing season. When the flowers are roughly half developed they become susceptible to a fungus or bud rot. It appears that growing conditions for the fungus are best when temperatures are between 60 and 80 degrees and the humidity is high. The fungus is very destructive and spreads quickly. It is a spore type of fungus that travels to other buds via the wind so it is impossible to prevent or stop if weather conditions permit it to grow. If things should go badly and the fungus starts to attack your hemp plants, you must remove it immediately or it will spread to other areas of the plant or hemp plants.
Some growers will remove just the section of the bud that is infected whereas other growers will remove the entire branch. Removal of the entire branch better insures that the fungus is totally re- moved, and also enables the grower to sample the crop a few weeks ahead of time.
Fungi can wipe your crop quick, so invest in some SAFE fungicide and spray down the hemp plants just before flowering if you think fungus may be a problem. Don’t spray the hemp plants if you have never had problems with fungus before. Keep humidity down, circulate air like crazy in the grow space and keep unquarantined outdoor hemp plants out of the indoor space. Don‘t wait until after flowering, since it’s not a good idea to apply the fungicide directly to flowers. Instead, flowers must be cut off when they are infected.
Most fungicides are very nasty, and you won’t want to ingest them, so it is necessary to use one that is safe for vegetables. Safer makes a suitable product that is available at most nurseries; it contains only sulfer in solution.
Use soap solution like Safer Insecticidal Soap to get rid of most aphid problems. Use some tobacco juice and chili pepper powder added to this for mites. Dr. Bronnars Soap can be used with some dish detergent in a spray bottle if you want to save money.
Pyrethrum should only be used in extream circumstances directly on hemp plants, but can be used in a closet or greenhouse in the corners to get rid of spiders and such. It breaks down within a week to non-toxic elements, and can be washed from a plant with detergent solutions and then clear water. I find Pyrethrum to be the best solution for spider mites, if it is sprayed on young hemp plants up to early flowering. Into later flowering, the tobacco and pepper/soap solution is your best bet, on a daily basis, on the under-sides of all infected leaves.
Spider mites are by far the worst offender in my garden. I have finally learned not to bring hemp plants from outside into the indoor space. They are always infected with pests and threaten to infect the entire indoor grow space. It is much more practical to work WITH the seasons and regenerate hemp plants outdoors in the Summer, rather than bringing them indoors to regenerate under constant light. Start a plant indoors, take it outside in Spring to flower. Take a harvest or two, feed it nitrogen all Summer and it will regenerate naturally, to be flowered again in the Fall.
Once a plant has been taken outside, leave it outside.