Do Potted Plants Grow Better Inside of Transparent or Non-Transparent Pots?
Watching plant roots grow in transparent pots provides an interesting look below the surface, but those clear walls don’t suit all plants. Many common potted plants grow much better in nontransparent containers. For plants that naturally grow in soil, opaque pots lead to better growth above and below ground. Plants with light-seeking air roots, which naturally grow without soil, do well in clear containers.
Soil Roots and Darkness
When roots naturally grow below the soil surface, nearby light signals they are headed the wrong way. Like stems, roots contain growth-directing hormones known as auxins, which tell them which way to grow. In the same way that upper growth on plants bends toward well-lit windows, roots naturally grow away from light. They seek darkness and protective moisture instead. In transparent pots, these roots avoid light-penetrated areas of soil. Forced into high-light areas, light-sensitive roots recoil and slow or stop growth. When light dries soil out, tender root tips can suffer.
Air Roots and Light
Some roots were meant to see daylight and draw energy from the sun. Epiphytes, sometimes called air plants, draw water and nutrients from the air through exposed roots that cling to trees or stones. Transparent pots provide these roots with inviting homes similar to their natural environments. Epiphytic moth orchids (Phalaenopsis spp.), hardy in U.S. Department of Agriculture plant hardiness zones 10 through 12, flourish in clear pots. Moth orchid roots contain chloroplasts, seek out light and carry out photosynthesis. In nontransparent pots, healthy roots stay firm and white. Exposed to light through clear pots, moth orchid roots turn green with chlorophyll.
Clear Pots and Epiphytes
Air roots need a delicate balance between oxygen and moisture. Too much or too little water hinders healthy growth. Moth orchid roots, for example, should dry out slightly between waterings. The roots do not store water, nor do they tolerate drought, but given too much water, they suffocate and drown. Epiphyte leaves may not show distress until the damage is done. Clear containers take the guesswork out of watering these roots; moisture and dryness are readily seen. Moth orchid roots often escape opaque pots in search of light. They stay content and confined in transparent pots.
Dark Pots and Soil-Dwellers
Nontransparent pots invite naturally soil-dwelling plants to take up every inch of soil. To benefit from soil nutrition, roots need nutrients in soluble forms they can absorb. Some nutrients move easily through soil with water, but others stay immobile and barely move at all. Unless roots venture into soil where those nutrients lie, they miss out on their benefits. Light-dried soil limits absorption, too. Soil-dwelling plants grown in nontransparent, light-blocking pots take it all in. They develop more extensive, healthier root systems and better above-ground growth than when their containers let light through.
Do Potted Plants Grow Better Inside of Transparent or Non-Transparent Pots?. Watching plant roots grow in transparent pots provides an interesting look below the surface, but those clear walls don’t suit all plants. Many common potted plants grow much better in nontransparent containers. For plants that naturally …
Is it OK to grow plants in clear (transparent) pots?
I was using old clear (transparent) plastic meat packaging to grow plants in. Is that a good idea? Are there any side effects of roots possibly being exposed to the sun?
8 Answers 8
Roots exposed to the sun might think they have reached the surface and start to put shoots out.
Those particular containers don’t look very strong – don’t underestimate the weight of wet soil. Ideally you should have some more rigid that does not collapse under the soil’s weight or when you move them.
Do these containers have holes in them? Holes in the bottom are required for drainage, but holes in the side could wet (and degrade) black paper/card as recommend by @shanna.
Plastic pots can be okay, but you need something stronger and opaque. All plastic pots will eventually degrade with the UV from the sun. Perhaps not a significant problem at high latitudes, but here in Texas, they definitely have a limited life (as does plastic garden furniture!) and some are better than others.
@gunbuster mentions plasticizers. I suspect in this application they are less of a problem than in food containers, but this is another good argument for containers that are sold as plant containers.
Plastic is not a good medium. It traps heat, melts in high temperatures and contains plasticizers (especially in soft plastic like yours) which may dissolve into the soil.
In addition, your container is too shallow for most plants. It can only be used as container for plant germination.
If you’re stuck for containers and this is your only option (or you want to be environmentally friendly and re-use those pesky non-recyclable food trays), you could glue something like black paper or cardboard to the outside to keep the light from getting through.
What do you mean when you say that you are using clear plastic containers to grow plants?
Starting from seed, as seedlings, indoor plants that don’t want direct light and whose roots aren’t totally root bound?
I suspect all of the above would be fine, although the indoor plants may have problem with not enough soil depending upon the plant. Similarly, there may be some seedlings which need deeper soil level than that.
The other replies are all applicable, but I can think of situations where it would not be a problem, and there are probably others. What is your goal, and what are the specifics?
Another major problem is algae. As algae needs light and moisture, the bottom part of the pot is the perfect place to grow.and once grown algae can destroy the root system ,And even if there is a little bit of algae the plant wont survive.
Clear pots can be great for plants, especially transplants. Plants vary a lot, but in general, the roots reach the edge of a clear container, feel the sun, and stop growing. This prevents them from getting root bound. Once transplanted into the ground the root start growing with a minimum of transplant shock. Broccoli is an example of a traditionally transplanted crop that can really root bind and benefits from clear containers. Better yet is soil blocks. no pot. Blocks work great for large operations. Gardeners may find clear cups more convenient and economical.
I have been using plastic shoe boxes with transparent fitted covers or with plastic wrap covers, plus salad green boxes and other such transparent boxes for 5 years now with:
- never a box lost to disintegration into the soil
- never a problem with plant’s roots
- with care about ventilation and placement such that plants would not overheat
- care to inspect the contents frequently enough to verify that there would be enough moisture in the box
- place drain holes through the bottoms of some boxes that contained plants that needed watering as opposed to misting with rainwater or distilled water
- care that tap water salts from the dissolved solids in most of our tap waters did not concentrate in the potting medium as moisture evaporated from the boxes
- care that boxes that were not adequately vented for pressure changes with changes in ambient temperature did not suck in misting water that was too high in dissolved solids, etc.
I would further say that I had to learn some of what I mention above the hard way, after inspecting plants, the contents of the boxes too infrequently.
Another thing to consider with transparent boxes is the tendency of algae, including some species that you might really not want, and also cyano-bacteria to grow in such boxes if the bases are exposed to light. Therefore, consider shielding the bases in many situations with aluminum foil wrapped up to the soil or planting medium line. If sunlight is to shine on the box during warm weather, avoid dark foils and avoid black paper, unless your objective is to cook the plants.
I acknowledge that there are some plant genera and species that would not do so well with too much light getting into the pot sides. so shield those roots from light with something that reflects light, unless you have a particular reason to need to warm up the roots. There are plenty of plants that like that, too, but don’t let them reach cooking temperatures, which can be as low as 65 degrees for some species that I’ve grown or well over 100 degrees F for others. Get to know your plant’s requirements, first. Some will want lids on the boxes and some won’t.
Another point well made in response to the original question was that one can often use recycled containers. I have found reasons to use 1/2 gallon plastic milk boxes on their sides, plastic clam shell produce boxes, both those with ventilation slots and those without same, plastic meat boxes that have fitted transparent lids and black bottoms, etc. I have used cupcake boxes, both new and recycled, plastic cake boxes, etc. I only buy the new ones for use as very large community pots or very large germination flats.
Is it OK to grow plants in clear (transparent) pots? I was using old clear (transparent) plastic meat packaging to grow plants in. Is that a good idea? Are there any side effects of roots