Dear Danko: Expert Grow Advice

Odor control, hydroponic mother plants, yellowing leaves, stretching seedlings and more.
Dear Danko: Expert Grow Advice
High Times/ Justin Cannabis

High Times’ cultivation specialist Danny Danko answers all your burning questions about being the best grower you can be. But first, some quick tips from the expert himself:

  • When growing indoors in winter, elevate your plant containers and reservoir above the floor to avoid damaging roots with cold water.
  • Any yellow or brown leaves should be removed from your plants to prevent pests and mold.
  • Harvest your plants during the dark cycle to preserve terpenes and other essential oils at their optimum levels.

Subject: Odor Control
From: Rob G.

I live in an apartment and have a legal prescription for medical marijuana. I am concerned about the smell, though, if I decide to grow my own. What about grow tents or anything else for maximum discretion in terms of cost and practicality?

Dear Rob,

Odor control is an important part of cannabis cultivation, particularly as you approach harvest and during the drying process when the smell of your medical marijuana will permeate the surroundings. My advice is to use a strong inline fan to exhaust all of your “spent” warm air through an activated-charcoal filter.

Filtration will eliminate much of the odor as long as you’re pumping out enough air to cause negative pressure within your grow area. This means the amount of air being expelled from your garden will pull in fresh air though any cracks and thus keep odors from escaping from your grow space.

A grow tent is a good and affordable way to accomplish this, and most of the ones I’ve seen already have built-in vents and some even come with a fan and filter. If you’re not growing perpetually, you can use the tent as a drying chamber and take advantage of the filter during this most odiferous of times.

Subject: Hydro Mother Plants
From: Alan

What is the best hydroponic method for long-term growth for mother plants?

Dear Alan,

I usually recommend that people grow their mothers in soil or coco because those mediums are more forgiving over long periods of time. Also, plants grow more slowly in soil, so unless you need clones all the time, you won’t have a huge, unmanageable tree to trim continually.

However, if you do choose the hydroponic route for your mother plants, my first recommendation would be to utilize the deep-water-culture (DWC) technique. This allows plenty of space for roots to grow, and the greater amount of water it employs allows you to change out your reservoir less frequently.

Most hydroponic systems are built to grow more than one plant, but DWC can be easily used to grow a massive bush with plenty of branches and shoots from which to take clones. Just make sure you completely change the nutrient solution at least every two weeks, taking care to make sure it doesn’t get too warm or cold.

Subject: Yellow Leaves
From: AK

My plants have slightly yellowed leaves, but I seem to have my pH at the level it should be—around 6-6.5. Is this a problem, and, if so, how can I fix it?

Dear AK,

It sounds like your plants are suffering from a nitrogen deficiency. Because the pH is within the normal parameters, this is an easy problem to diagnose and treat. If the pH was over or under the recommended levels, I would suggest that you might need to fix the imbalance first, but at 6-6.5, all signs point to a lack of nitrogen.

You can provide your plants with a boost of nitrogen in a number of ways. If you’re using bottled nutrients, add a healthy dose from the bottle labeled “Grow” or “Vegetative” with a high first number in the NPK (nitrogen, phosphorus, potassium) rating. Otherwise, you can use organic additives such as liquid seaweed, liquid fish or seabird guano. You should see your plants green up within a few days to a week after application.

Subject: Seedling Stretch
From: Joshua B.

Sprouting seed has been easy for me, and transferring it to soil has been fine too. My problem is that the seedlings all grow straight up 6 inches or more before their weight causes them to fall over. I have a plant light that I run properly. What is the issue? Am I not planting seeds deep enough, or is it something else?

Dear Joshua,

My initial diagnosis is that your light is too far away from your plant tops. This is usually the reason that seedlings will stretch and then fall over. Adjust your light so that it is closer to your seedlings, and you should see this problem disappear.

If your seedlings are still alive, try to carefully remove the plant from its container and replant it with much of the stem buried in soil. To do this this, you should wet the soil, flip the container over with your fingers while protecting the stem and then gently remove the plant with the wet soil attached. Replant the seedling in a deeper container (or the same container, if you can and wish to do so), burying the stem nearly up to the first leaves. Some light airflow from a fan can also help strengthen the stems so that they are more able to bear the weight of the plant above.

Subject: Cloning From Vegging or Flowering Plants
From: Invictus Grower

My crop is currently in the vegetative stage, and I’m almost ready to take clones. I have read about and seen the technique of taking clones from a mother or another plant while it’s still in veg, but I’ve just stumbled across a technique called monster cropping—basically, taking a clone from an already budding/flowering plant in the first few weeks of flower and reverting it back to veg. Which technique is best—veg clone or monster-crop clone? I have done some research on monster cropping and it seems there’s no definitive answer.

If monster cropping is best, is it better to cut the small popcorn buds off and make it look like a veg clone, or should I leave the small buds on? I have seen videos of both techniques, and when the buds are left on, the bud sites grow a crazy number of branches when the plant reverts to veg. I would love to hear your thoughts on veg cloning versus monster cropping.

Dear Invictus,

I do not advise taking clones from flowering plants. The extra time it takes to revert them back into the vegetative stage and the potential to stress out the plant and cause it to react with strange behaviors such as hermaphroditism or whorled phyllotaxis are too great. The healthiest cuttings come from strong and healthy vegetative plants, so feel free to take clones from your plants in veg but avoid taking clones from budding plants.

I’d only recommend taking a clone from a flowering plant to save genetics from being lost. If you’ve found a unique and amazing flowering plant and you want to keep it around to make a mother plant from it, take a clone, root it and place it under 18-20 hours of light per day. Eventually, it will revert back to the vegetative state, allowing you to preserve its genetics for future use.

Subject: Plant Limits
From: Duke

I’m considering changing the amount/size of plants in my grow-room. I’m running eight 1,000-watt lights and growing in soil in 10-gallon pots. Considering that I mostly raise Kush varieties, I’m wondering if I should grow more plants in smaller pots or if I should just stay with something similar to what I’m already growing. I’ve been averaging around .25 grams per watt, and I’m trying to get closer to .5. Thanks in advance for your help.

Dear Duke,

The first thing you should consider when adding more plants to your garden is the legality of your grow. In most states, the more plants you have, the greater the penalties, and federal plant limits should also always be a consideration. So please do the research and find out how many plants you can legally grow or what the penalties are for your desired amount of illegally grown plants. is a great resource to learn about the cultivation laws in your state.

Second, you should know that the fewer plants you grow, the longer your vegetative time will be to get the plants larger in order to fill up your space. When growing more plants that are smaller, you will have a shorter vegetative time and thus be able to harvest sooner. You also will have less time for something to go wrong along the way such as issues with overfeeding or pest infestations.

The best thing you can do to increase your grams per watt is to keep your environment totally controlled so that there aren’t any fluctuations in temperature and humidity. Adding CO2 gas injection also boosts yields. Avoid using plant-growth regulators as they are not meant for plants that we consume and they contain chemicals that have been deemed unsafe.

Subject: When to Induce
From: Zach R.

I was wondering how to tell when it’s time to switch to a 12/12-hour day/night light cycle.

Dear Zach,

The decision as to when to induce flowering in your plants is entirely up to you. It’s important to determine how much space you have and to factor in the fact that your plants will stretch for at least a few weeks after flowering is induced. I usually recommend one week per gallon of container you use, so a plant in a 5-gallon bucket should get approximately five weeks of vegetative time before the switch. Plants in a 2-gallon pot need two weeks to vegetate.

The longer you vegetate your plants, the larger they will be, but that also allows time for things to go wrong. Overwatering, overfeeding and pest infestations have more of a chance to manifest into bigger problems, and your plants can easily become root-bound and end up not yielding as much.

Originally published in the July, 2019 issue of High Times magazine. Subscribe right here.

  1. I live in Illinois where it has just become legal.I have a Medical Card so I am able to grow 5 plants. I want to get clones. Where do you recommend I purchase them from ?

  2. I have a 5 1/2 ft alaskin thunder fuck plant that is in budding.i have it in my grow room 12on,12off in a controlled climate. What is the best temperature and humidity while budding? Also when harvest i don’t want to kill the plant,how can I harvest and keep it growing for a second harvest from same plant?
    Thank you

    1. As he mentioned in the article, Its very hard to cut clones from an already flowering plant and it’s not recommended. As far as humidity, I like 50% with a lights on temp of 75F for soil….and if I’m doing hydro I’d shoot for even lower humidity levels if possible as Ive had root balls take on mold/rot with high humidity levels.

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