How bright is bright enough? Is the light too bright? Those are important questions to be asking when you are trying to grow plants which are essentially 'solar powered' after all. Plants need light to convert carbon dioxide and water into the carbohydrates that they live on through a process called photosynthesis. In fact, even this process requires some carb burning energy to carry out as does everything a plant does, even taking up water (which isn't as passive of a phenomenon as we used to think: but that's another post for another time). If a plant doesn't get enough light, it can't keep up with the energy demand and begins to slowly starve to death.
No amount of added water nor fertilizer (organic or not) can make up for it either. In fact, fertilizing light-starved plants can actually make them worse off as excess nutrients, especially Nitrogen, can stimulate the plant to grow more rapidly, which increases its need for carbohydrates. If it's still not getting enough sun, this will only make it weaker and more susceptible to insect damage and disease as well as making it etiolated. Etiolated means that the plant becomes flimsy, delicate and less able to withstand wind, being bumped into and other stresses because all this new growth is made up of cells that have thin walls and lack the support they need.
Not every plant needs the same amount of light either. Some plants were created or 'evolved' (whichever you believe doesn't matter a hill of beans to the plants, so the argument is irrelevant in these discussions) to thrive in different light environments. Plants that originally come from the understory of forests or the mouths of caves need a lot less light, for example, than plants that come from the wide open spaces of a grassland or desert. Knowing what levels of light the plant you are interested wants most is critical to helping you keep it alive. It also helps to know what light conditions the plant was raised, or at least kept in for a long time, prior to you buying it if you get it as a potted plant.
If the plant was raised indoors (which for most of us, is quite a dark, still place as far as plants are concerned), then it is going to struggle to survive outdoors in full sun and wind. When you buy plants, pay attention to where the store keeps them. If they are kept inside the store or under a dense shade cloth outside, they will need shade at your place. These plants will need almost full shade and wind protection, especially in the low humidity that we have in the Desert Southwest. Otherwise, they are likely to suffer broken branches and sunburn. Yes, plants can get sunburned even easier than people can. And unlike us, plant tissue that gets sunburned isn't easily replaced. The damage is usually permanent. If it's on the leaves, the plant can grow new ones, if it is given some shade, water and nutrients that is. If it's on the stems, you might as well prune off those stems before boring insects work their way into the cracks in the epidermis (outer 'skin') of the branch. If it's on the trunk of a perennial plant like a tree, the tree is, sadly, very likely doomed to be infested with borers, that will eventually kill the plant, here in the desert. It's best to avoid sunburn with plants rather than to try to save plants from it after the fact.
The best way to avoid having wimpy plants that can't hack it outdoors is to grow them by seed out in the climate that you plan to keep them in. Growing by seed takes time and patience, but can be quite rewarding as you watch the plants grow. It can be a great opportunity to teach your kids some science at home too. This way, the plant becomes acclimatized to the conditions and will do better than many transplanted plants might do. Of course, it only works if the species you are planting is originally from that sort of climate to begin with as we discussed above. A fern won't grow well in full sun just because you planted the spores in full sun to start with and a sunflower seed planted in full shade won't make you a shade-tolerant sunflower plant. But, at least by starting those sunflowers out in soil in the sun and wind, they won't be etiolated and will be strong enough to live up to their genetic potential.
So, you're wondering what the gadget in the photo is right? That is one of many versions of a tool that can help people get a more accurate idea of how light or dark a place really is. It's a luxmeter, a gadget you may have seen photographers use for portraits or setting up scenes for movies. They are great for helping you make sure that the camera settings are right to avoid over or under exposure. You know all those silhouettes and washed out 'ghosts' you get when you take candid snapshots with your phone or 'Instamatic' cameras? Luxmeters are how the pros avoid that unless they want those effects for some artistic purpose. They used to be expensive, but now you can find them for as little as $10 on sale.
The eyes can deceive you when you look at a location and make you think that things aren't as dark as they really are. That's because our eyes have pupils that dilate when we are in low light conditions to let in more light. But to the plants and the luxmeter, it's still as dark as it always was. Using a luxmeter, we can record how much light different places on a property get at different times of day and different seasons. Then we can create light zone maps much like we create water zone maps (which we'll discuss in another post). Both maps help us to determine which species of plants will do best in different parts of the property. A pincushion cactus, for example, will do better in spots with a high lux reading and a low level of available water, while a fern will appreciate conditions that are the opposite.
We're using extreme examples here, but even plants that aren't as obvious, like pansies or violets, for example, benefit from such planning. Pansies and violets come from forest under-stories, but from the more dappled or partial shade areas than most ferns do, so they require partial sun and a moderate amount of water (neither drying them out nor soaking the soil will make them happy). Pansies are tough and easy to grow, even in the desert, as long as they get afternoon shade and a little water on a regular basis. Knowing whether the shade they are getting is too much or too little can be easier with a luxmeter rather than checking the plants and trying to move them after they begin to show signs of stress. Transplanting plants to a shadier spot after they've gotten too much sun doesn't always save them, because now you've added the additional stress of digging them back up and exposing the roots again, so it's best to plan ahead before you plant them.
Like any gadget, luxmeters are helpful, but no substitute for experience and education. You still need to know enough about the plants, soil, water etc. to make the readings you get from these things mean anything to you in terms of how you garden.
No amount of added water nor fertilizer (organic or not) can make up for it either. In fact, fertilizing light-starved plants can actually make them worse off as excess nutrients, especially Nitrogen, can stimulate the plant to grow more rapidly, which increases its need for carbohydrates. If it's still not getting enough sun, this will only make it weaker and more susceptible to insect damage and disease as well as making it etiolated. Etiolated means that the plant becomes flimsy, delicate and less able to withstand wind, being bumped into and other stresses because all this new growth is made up of cells that have thin walls and lack the support they need.
Not every plant needs the same amount of light either. Some plants were created or 'evolved' (whichever you believe doesn't matter a hill of beans to the plants, so the argument is irrelevant in these discussions) to thrive in different light environments. Plants that originally come from the understory of forests or the mouths of caves need a lot less light, for example, than plants that come from the wide open spaces of a grassland or desert. Knowing what levels of light the plant you are interested wants most is critical to helping you keep it alive. It also helps to know what light conditions the plant was raised, or at least kept in for a long time, prior to you buying it if you get it as a potted plant.
If the plant was raised indoors (which for most of us, is quite a dark, still place as far as plants are concerned), then it is going to struggle to survive outdoors in full sun and wind. When you buy plants, pay attention to where the store keeps them. If they are kept inside the store or under a dense shade cloth outside, they will need shade at your place. These plants will need almost full shade and wind protection, especially in the low humidity that we have in the Desert Southwest. Otherwise, they are likely to suffer broken branches and sunburn. Yes, plants can get sunburned even easier than people can. And unlike us, plant tissue that gets sunburned isn't easily replaced. The damage is usually permanent. If it's on the leaves, the plant can grow new ones, if it is given some shade, water and nutrients that is. If it's on the stems, you might as well prune off those stems before boring insects work their way into the cracks in the epidermis (outer 'skin') of the branch. If it's on the trunk of a perennial plant like a tree, the tree is, sadly, very likely doomed to be infested with borers, that will eventually kill the plant, here in the desert. It's best to avoid sunburn with plants rather than to try to save plants from it after the fact.
The best way to avoid having wimpy plants that can't hack it outdoors is to grow them by seed out in the climate that you plan to keep them in. Growing by seed takes time and patience, but can be quite rewarding as you watch the plants grow. It can be a great opportunity to teach your kids some science at home too. This way, the plant becomes acclimatized to the conditions and will do better than many transplanted plants might do. Of course, it only works if the species you are planting is originally from that sort of climate to begin with as we discussed above. A fern won't grow well in full sun just because you planted the spores in full sun to start with and a sunflower seed planted in full shade won't make you a shade-tolerant sunflower plant. But, at least by starting those sunflowers out in soil in the sun and wind, they won't be etiolated and will be strong enough to live up to their genetic potential.
So, you're wondering what the gadget in the photo is right? That is one of many versions of a tool that can help people get a more accurate idea of how light or dark a place really is. It's a luxmeter, a gadget you may have seen photographers use for portraits or setting up scenes for movies. They are great for helping you make sure that the camera settings are right to avoid over or under exposure. You know all those silhouettes and washed out 'ghosts' you get when you take candid snapshots with your phone or 'Instamatic' cameras? Luxmeters are how the pros avoid that unless they want those effects for some artistic purpose. They used to be expensive, but now you can find them for as little as $10 on sale.
The eyes can deceive you when you look at a location and make you think that things aren't as dark as they really are. That's because our eyes have pupils that dilate when we are in low light conditions to let in more light. But to the plants and the luxmeter, it's still as dark as it always was. Using a luxmeter, we can record how much light different places on a property get at different times of day and different seasons. Then we can create light zone maps much like we create water zone maps (which we'll discuss in another post). Both maps help us to determine which species of plants will do best in different parts of the property. A pincushion cactus, for example, will do better in spots with a high lux reading and a low level of available water, while a fern will appreciate conditions that are the opposite.
We're using extreme examples here, but even plants that aren't as obvious, like pansies or violets, for example, benefit from such planning. Pansies and violets come from forest under-stories, but from the more dappled or partial shade areas than most ferns do, so they require partial sun and a moderate amount of water (neither drying them out nor soaking the soil will make them happy). Pansies are tough and easy to grow, even in the desert, as long as they get afternoon shade and a little water on a regular basis. Knowing whether the shade they are getting is too much or too little can be easier with a luxmeter rather than checking the plants and trying to move them after they begin to show signs of stress. Transplanting plants to a shadier spot after they've gotten too much sun doesn't always save them, because now you've added the additional stress of digging them back up and exposing the roots again, so it's best to plan ahead before you plant them.
Like any gadget, luxmeters are helpful, but no substitute for experience and education. You still need to know enough about the plants, soil, water etc. to make the readings you get from these things mean anything to you in terms of how you garden.