Containers - Know which is best for your plants

A while back I wrote about containers and suggested some minimum container sizes for plants that are good to grow indoors – Containers LINK. I would like to build on that and lead into the topic of how to set up a grow room which I will be talking about soon.  Most indoor growers will use several sizes of containers. Typically, plants are germinated or placed into small containers after germination and then transplanted to progressively larger containers until flowering. Starting many plants in small containers allows the grower to pick the best plants and get rid of the weak ones. Good growers cull inferior plants at each transplant. Starting many plants also allows growers to look for traits and attempt to incorporate these traits into a breeding program.

Seeds can be germinated in starter plugs and grown for 1- 3 weeks. If you are not growing in new potting soil, you should add nutrients. Young plants need all nutrients (N-P-K and micronutrients) but for seedlings, like cuttings you should give them a fertilizer with a high phosphorus percentage to promote root growth. No matter what nutrient regime you use, your plant growth will be inhibited if you do not transplant them into a larger container. I like the starter plugs because like rockwool they are easy to move and I think really minimizes any transplant shock. If I don’t use a starter plug I like to start seeds on paper towels and put a seed in a plastic cup with a potting soil mix. I like plastic cups because they are cheap, easy to get and are light and easy to move around. A six ounce cup will hold a plant for 1-2 weeks maximum. I use the 16 or 20 oz. cups for 3-4 weeks respectively. A half gallon container  is good for plants for upto six weeks. For minimum sizes for different plants please see my previous container post .  A good rule of thumb I have heard is that you should give a plant ½ gallon of medium to support 1-2 feet of growth. This rule depends on your use of fertilizer and proper watering. Obviously, plant growth habits differ so if you have a plant that has branching you should grow your plants in larger containers. As you can see in the picture at the bottom of this post, plants grown in containers that are too small are stunted and I can tell you will have lower yields.

While transplanting or ‘potting up’ is important to save space and enable a grower to pick the best plants from many, plants do better if they are NOT transplanted often. You can count on losing 3-4 days of growth after each transplant. However, if you are growing many different plant types, have multiple grow areas, or move your plants around you will need to do some transplanting to be a good grower.

As I have mentioned, my favorite containers are plastic pots. Plastic pots are inert, reusable, lightweight and convenient to use. Metal containers may react with the medium, nutrients or plants. Plastic bags are also convenient with their square bottoms. Fiber containers are also popular and I have used many types myself. They are not too expensive, can be used for more than one growing cycle and are easy to dispose of in a compost pile or in an outdoor garden as organic matter.
I will end with one last piece of advice concerning containers…. When you are transplanting into larger containers, some growers put sand or gravel at the bottom to increase drainage but also to balance the plants so that they do not easily tip over.

Good Growing,
Dr. E.R. Myers

In the picture below, notice the two white meter sticks between the plants.   I have planted 1, 2 and 3 corn plants in identical sized small plastic containers. I assume this means that the plant have 100% 50% and 33% of growth medium from left to right. You can see the size difference with your own eyes. For this little experiment, all plants germinated the exact same day, were grown under the same 600 watt HPS and given the same fertilizer regime. These plants are also a hybrid from the same batch so they are genetically the same. The only difference is due to the lack of container space for the roots. Notice too that the single plant on the left is a darker green. This is a sign of plant health and vigor. I have noticed that plants that are in larger containers and growing rapidly have a greater disease resistance than plants that are stunted in small containers. You may hear people tell you that you can grow plants in small containers if you provide all the right nutrients and water but if you have small containers and your plants roots are not growing this means that overall above ground growth and yield will be lower. Growing roots send out hormones telling the plant that things are ok and that is should continue to grow. If a root is blocked inside a small container it will tell the rest of the plant (via hormones or other molecular signals) not to grow since water and nutrient uptake may be limited.

E-mail - Odor control + fungal spore control in one

Hello Dr. Myers,
 Great web page.  I have a 5ft by 4ft closet what is the best way to control odor.
Thanks,
Sent from my iPhone

Hello and thanks for your question.
I personally use a 4" carbon filter which will control any odor.  It is also awesome in that it cuts down on fungal spores which is the primary reason I use it. I have it sit on top of an upside down 5 gallon bucket so there is good air flow into the filter. This may take up a bit of space under you light, but it will be worth it for disease and odor control. Most other products simply mask any smell and do nothing to actually clean the air. In other words, without a carbon filter you are hiding your problem for a time and not solving your problem.  
To save space under the light and if your grow area is high enough you could build a shelf above the light to sit the filter on.  They are heavy so make sure it is a strong shelf that can support the weight.  A carbon filter should control any plant odors you are worried about.  I started to use it because some semesters my plants are hit by a leaf fungus. I noticed a SIGNIFICANT DECREASE in affected leaves on plants in the grow area with the filter while I had dead plants with yellow/necrotic leaves in another grow area that did not have a filter.


I think the 4" will be good for your room. You can just let it run in the room or do what I do, have a flexible dryer hose attached to the fan and blow the clean air over the tops of the plants directly at my HPS. This air flow keeps the plants from being stressed by the heat of the bulb by blowing/circulating the hot air around the room.  If you have a large wattage bulb and heat is a problem you could vent the hot air out of the room, it will be odorless and clean.


Good Growing,


Dr. E.R. Myers

Pests -- ROOT APHIDS

Hi Dr. Myers,

How do I get rid of these persistent pests(root aphids). I have tried
several organic pesticides including neem oil and potassium salts with no
effect on them.
Thanks,

Some of the same things that work for 'normal' aphids will work on root aphids see my post on aphids

There are several options, none are fool proof. First, there is a fungus that kills insects (Beuveria bassiana) This is sold under two brand names that I know of, (any readers please let me know if you know of others) Botinigard and Naturalis. This fungus is mixed with water and sprayed on the plants making direct contact with the aphids is important. This is one reason root aphids are so hard to control; there are so many nooks and crannies in soil and other mediums that almost any treatment is bound to miss a few pregnant females. In fact, one study I read showed that the number one reason for difficulty controlling root aphids is lack of proper application of the chemical or pathogen. I should mention too that the finer the mist the better. Also, since this fungus gets on the skin of aphids, and aphids that are growing rapidly can shed their skin every 3-5 days you should reapply the fungus every 3-5 days. In Europe they use a fungus Verticillium lecanii with much success. I think this is still in the process of being approved by the EPA, but you could do a search for it.

Second, you can apply chemicals like Neem, pyrethrum etc. to the roots and above ground parts of plants. For root aphids it is recommended you soak the root balls in an insecticide for 5 minutes. There are studies that show soaking in any insecticide for less than 5 min. will result in far less than 100% dead (you don’t fix the problem) so soak longer rather than shorter.

You could also try and not use insecticides by soaking plants for several hours in dish soap as I recommended in my post about general insect care

If you see them in clusters (aphids tend to be gregarious) you have a major infestation and maybe a very serious problem. Large clusters mean you have a chance to have winged aphids, which can fly to new plants anywhere in your grow room, green house, home or garden. The bigger and older the grouping, the greater the chance of winged aphids in your area.

Biological control is possible for these aphids as well. Before you buy predatory insects/organisms look at the shipping routes, release rates and timing. Mail is susceptible to very cold, maybe freezing temperatures. Also, some predators are better than others depending on what species of aphid you have. If you can figure out the species you will have more success.

There is a predatory aphid midge (Aphidoletes aphidimyze) that eats over 60% of all aphid species. The midges are shipped as larvae and 2-3 larvae are put on each plant. This midge likes humid conditions so cutting down on the exhaust fan or putting in a humidifier to increase humidity will increase its success, but watch out for mold.

The last result is to start over with seeds after you sterilize everything with hydrogen peroxide or bleach and a good hot soapy wash. If you can't start from seed you could try cuttings, but they may have aphids on them (root aphids are not always on the roots) So, you must soak any cuttings in insecticidal soap or in dish soap for a long time. This will kill many plants but you need to make sure you are not just starting over with the same problem. As with all insect infestations, prevention is better than a cure, so think about how you go them. I know many people have gotten insects by buying top soil. I try to NEVER buy top soil if it is stored outside for long periods. It is easy for soil gnats or root aphids to get into it and into your garden.

I hope this helps, Let me know if anything works, I’d like to help other readers in the future with specific results.

Good Growing
Dr. E. R. Myers

PESTS -- soil gnats + recommended organic insecticide

Hi Dr. Myers

Thanks for taking my question as always. This time its about some pests I have observed in my indoor garden. I have noticed lots of small flying insects that I suppose are either gnats or fruit flies. I think the culprit must be the soil mix I used as the gnats seem to congregate on the soil.
Second, I noticed some of the leaves on my plants are being eaten up, like by a
leaf cutter. I did find a caterpillar in the dirt but he was so big I didn't think he could be the culprit. ( I took him outside)..
I used good soil ( Miracle grow Organic + perlite). Any suggestions on
soil mix ?
For insecticide, I currently am using Vinegar in a glass with a funnel. This is working but not completely. I was thinking about "Safer Soap" or getting some LadyBugs. What is your opinion? Do you have any other suggestions for a "safe" insecticide?

Hello, thanks for your question.
It sounds like you have soil/fungal gnats. I have bought dirt from the big box stores that had gnats more than a few times. They eat organic matter out of the soil, and should not bother your plants too much. However, if you see small yellow dots on the leaves, you have some other leaf sucking insect.


The gnats can be a real pain, even if they don’t directly feed on your plants. For me they get stuck all over my HPS bulb, and they can get stuck in plant parts too. If they get stuck to your plants they can be a place for mold/fungus to grow which can harm/kill your plants.


If you are growing plants that live years, you may have to use some chemical insecticides. HOWEVER, I would NEVER use a sythetic insecticide in a plant I was going to eat, drink, or otherwise consume. If it is in the plant, it will then be in you. There are a few products under pests at HTGSUpply.com you could use and I have read that soil gnats are susceptible to pyrethrum.


If you want my recomendation on an organic insecticide, try nicotine. Yep, that’s right nicotine is made by tobacco as an insecticide (think of that if you use tobacco products). Nicotine is organic and will break down into non-insecticide molecules in time. Soak the contents from a couple cheap cigars in a gallon of water, I use a five pack of Philly Blunts but any kind will do. I add a couple drops of dish soap to the gallon of water as this will help the tobacco-water coat all soil particles when you water the plants with it. After letting the cigars soak for a day or two I water the plants trying to get the entire surface wet. The gnats live and eat in the top layer so you are not trying to do more than saturate the top few inches/cm of your soil.  Let the soil dry out completly before watering again and water from the bottom if you can.


Another non- insecticidal way to get rid of them, is to let the top layer of your containers dry out. It would also help to water the containers from the bottom if you can. If you water from the top, let the top REALLY dry out to where the plants almost wilt. While doing this, I have also taken perlite and put a 1-3 inch layer of perlite on top of my soil, so that the gnats can't get to their food source (the soil) easily. The perlite also dries out quickly which makes it harder for the gnats to feed and breed. If you are growing an annual, where you can start completely over maybe you can just keep the vinegar/funnel going and keep your soil dry and get through this cycle. You then need to clean everything with hot soapy water and start over with new soil. You could put the soil in an oven set over 400 F for an hour if you want to sterilize it, but if you are using a lot of soil this might be too much of a hassle.

Last, how did that caterpillar get in? If you don't have screens, get them. Caterpillars start out as tiny little eggs layed by moths or butterflies. They can grow at a tremendous rate so there is a chance a butter fly laid an egg on your plants and you just missed seeing the caterpillar until it was large and you happened to be looking around for the gnats…

I hope this helps, let me know if you find any other bugs and what they look like and I may be able to help more.

Good Growing,


Dr. E.R.Myers

Hi Dr. Myers

I had been wanting to let you know that your suggestions completely
eliminated my (gnat/fruit fly?) problems.
I took perlite and covered the top dirt in all my indoor pots. After about 3 to 4 weeks, the little guys just disappeared. No Food !!
Thanks again...... you're the best !!!