While texting with my sister over the weekend about the sun requirements of a purple oxalis she purchased for her covered porch, it became apparent that some budding gardeners may benefit from me just starting at the beginning. Shade, part shade, dappled shade, part sun, SUN. All plants need some degree of it. Even the most shade tolerant houseplant would die if put in a closet. Well it may take a sanseveria a long time to do so but I'm sure that given time that sucker would bite the dust just the same as any of 'em.
First things first, figure the sun exposure of your garden, or the location your containers will be placed. Stand behind the garden space with your back to the house. Using a compass (you have one in the utility section of your iphone!) get a reading facing the garden. That is the direction your garden is facing and the sun exposure it gets; Southern exposure getting the most sun while Northern gets the least.
Now look up. See any trees? Is there a porch roof over your head? Any other shade producing structures around? These will all take away from the amount of sun the garden receives. To figure out exactly how much sun (hours per day) just choose a day to observe. Check every hour and note when the space comes in and out of sun. Not all sun is created equal. Afternoon is much stronger than morning so you'll need to know not only how much sun but WHEN.
So now you are at a reputable nursery. I cannot stress this enough. If you are finding this post helpful then you will no doubt have further questions when you are selecting plant material. Go to a locally owned nursery. The staff will be more helpful and knowledgeable (I used to be one of them!) and the plant material will likely be grown closer to where you live (better come transplant time) and of a higher quality. As with most things in life, you can't get somethin' for nothin' so be prepared to pay a bit more but it will be so worth the investment. These are living things we are talking about here!
While shopping read tags. I repeat, take the tag out of the container and read it! Your average plant tag will tell you the sun requirements, water requirements, hardiness zone, mature height, and spacing (how far apart to plant them).
Full Sun: Needs 6-8 or more hours of sun. Many of these plants can tolerate an entire day of sun and be completely happy as long as their moisture requirements are met. Most vegetables and herbs fall into this category as do many heat loving annuals and perennials. If you are looking to plant ornamentals in an area that receives absolutely no shade at all look for keywords "heat tolerant" and "drought tolerant". Ornamental grasses and succulents are not only interesting textural plants, they are also particularly good for all day blasting sun, as are Echinaceas, Rudbeckias, Salvias, Artemesia, Amsonia, Penstemon, Lupines, Baptisia, Hisbiscus, Scabiosa, Kniphofia, Nicotiana, Zinnias, and Yucca to name a few of my faves. If you are a container maven look for these top pics: Banana, Scaevola, Brocade geraniums, Echeverias, dwarf grasses, Sedums, Million bell petunias, Salvia 'Black and Blue', Basil 'African Blue', Kalanchoe thrysifolia, Senecio. I have a LOT of sun so a disproportionate amount of sun pics, sorry!
Light or Dappled Shade: These plants require little direct sun but need a days worth of filtered sun coming through deciduous leaf cover. They do not want heavy, dense shade. Woodland plants fall into this category. Aconitum, Anemones, Cimiifuga, Aquilegia, Carex, Chelone, Hellebores, Heuchera, Hosta, Ligularia, Thalictrum, and most ferns do well in this placement.
Part Sun/Part Shade: Need 4 hours of sun, preferably morning sun or evening sun. These plants will suffer if hit with much hot afternoon sun. I have gotten away with stretching some of these to have more sun here in Vermont than what they will tolerate in Virginia where the hot afternoon sun will fry an egg! Clematis, Astilbe, Aruncus, Hydrangea, Brunnera, Foxglove, Dicentra, Lobelia, New Guinea impatiens, Begonias, Tiarella, Japanese maples, and Fuschias need part sun.
Shade: Less than 4 hours of sun a day. This DOES NOT MEAN a dark place. If you have a structure (i.e. fence or building) that casts a dark shadow make sure that the plants are getting the 4 hours direct sun to counterbalance. Shade plants will also thrive in dappled or bright shade. The brighter the shade, the less direct sun the plant will require. Hosta, Impatiens, Ferns, Filipendula, Heuchera (many varieties can tolerate part sun), Rhododendrons, Daphne (sniff, sniff zone 7), Trillium, Solomon's seal, Aralia, and Yews.
Now, what if you have a plant in the wrong spot. Your plant will give you signs that it isn't getting what it needs before it up and dies so pay attention!! Scorched and yellowing leaves means it is getting too much direct sun. Often, it is too much hot afternoon sun.
Leggy (long stems, losing compact shape) plants are reaching for more sun, so they aren't getting enough. If your flowering plants aren't blooming that could also be a sign of not enough sun. Plants that have colorful foliage that has dulled or reverted to more of a green shade often are telling you they want more sun as well.
These are general guidelines. The most important thing is to pay attention to the health of each individual plant and adjust placement when necessary. With gardening there is always the occasional anomaly, shade plants in sun or vice versa that are happy, microclimates that are created and allow for something surprising. If it ain't broke don't fix it, and alert any plant breeder you know and they may be over to take cuttings!
When briefly trying to text all of this info to my sister she exclaimed that it was making her "head spin" and after this blog post I am feeling just about the same way. Before I go to take the boys to ride bikes near the lake I'd like to share a little bit of our family life with you.
Each night as we sit down to supper we give thanks for what is on our plate. We thank the cook, the farmer (or mama!) that grew the vegetables, farmer or hunter (papa!) for the meat, the animal that gave it's life, and Mother Nature for the rain and, of course, THE SUN (my father will be scoffing a bit now without the proper prayer but it ain't easy with a scientist for a husband and a few questions of your own!!). Without the sun we could not live. We are lucky to have whatever degree of it in our gardens where no matter how much there are always beautiful things to grow. Thanks to the sun. Amen.