Plan for Sunlight in the Garden

When creating any kind of garden plan one of the most important considerations is the amount of light the garden receives. Vegetable gardens and ornamental gardens are both affected significantly by the amount of light in the garden. Light changes two major aspects to your garden design: first the amount of light in the garden changes the plant selections and second light levels affect how those plant selections grow and thrive.

How Light Affects Plant Selections

In my vegetable garden my favorite vegetables every year are the summer vegetables including tomatoes, peppers, and squash. Those vegetable plants NEED a lot of sunlight and 8 hours of sunlight is probably a bare minimum to plan for those particular vegetables. Plants use that light to make sugars which they use to grow. We’ve all had that primer in elementary school science class, it’s photosynthesis! It makes sense, the more light the plants receive the better they can grow to their potential.

There are other factors that affect plant growth like water and soil but they all work in concert with the light to maximize the growth of the plant. As a gardener what I try to do is maximize and optimize each of those conditions for the type of plant I am attempting to grow.

Light on plants will also improve fruit production in a vegetable garden. Having the right amount of sunlight for your plant will maximize the yield.

Light Changes as the Garden Grows

As the season changes and we pass the summer equinox the light begins to lessen gradually each day. That seasonal change in the light will trigger plant changes. Plants will start to push toward seed formation in a rush to make seed before winter weather hits. The change in day light also is a trigger for trees to begin the process of moving toward dormancy. That change peaks in the fall when the colors in the trees change and the leaves eventually fall.

Light Changes As the Garden Grows

Another change of the light happens as your garden matures over the years. My garden was a completely blank slate in 2007 when we bought our home. The surrounding trees in the woods behind our lot combined with trees I planted and rogue trees I let grow have converted many areas of our yard into shade.

The Effect of Increased Shade

The increased shade has changed what I can grow where and as a result I’ve lots plants along the way. If you pay attention you can transplant and evolve with the garden. One area that changed was a side garden. That side garden began with sun plants like caryopteris. Along with the caryopteris I planted crape myrtle trees and hemlock for privacy. A dogwood went in as well as a Japanese maple. Now my side garden is completely shaded all day and the caryopteris will no longer grow there. The crape myrtles still do but only because they can grow tall enough to get sunlight.

The side garden when the caryopteris and crape myrtles were young.

The side garden was intentionally grown into a shade garden which now contains my hostas, heucheras, and hellebores as well as a few hydrangeas. Crape myrtles are excellent plants to grow to create shade using smaller trees. Just be sure to allow them to grow as trees and don’t trim them to the ground.

The Shade Garden Area in 2018

Increased shade and decreased light has also changed a bed in our front garden. The front garden used to contain a beautiful display of iris and salvia. Little redbud trees quickly became big redbud trees and now cover the garden in complete shade during the summer. It’s time to again covert the bed into another style with shade garden plants. I’ll be gradually transplanting the irises that are in there to another location and putting in hostas divided from other plants in the garden.

Plan for Changes or Plan the Changes

As gardeners it is often hard to plan for one season, let alone 10 but it is an important part of your overall garden design. Keep two things in mind as you design your gardens in regard to light:

  1. What is the goal of the garden you are designing?
  2. What is the light need to maintain that goal?

Light for a Shade Garden Design

In my case the shade garden was the ultimate goal for our side yard. It wasn’t a huge garden and at it’s widest point was only 15 feet or so between our house and the property line. I had to create shade to protect hostas so I planted fast growing trees (crape myrtle) that would eventually cover the area with shade. Hostas need a lower level of light to reach that goal and developed that level of light with additional plantings.

Fast Growing Plants that Create Shade:

Tulip Poplar, Maple (avoid silver maples), Crape Myrtle, Catalpa, Birch

Light for a Vegetable Garden Design

If your goal is a highly productive vegetable garden you will want the opposite to happen, you want to maximize the light in your design. Maybe you live in an area with a lot of trees and one thing you will have to do is thin them out to maximize your light. (I’m located in the northern hemisphere and if you are in the southern hemisphere reverse what I’m about to say. Thanks you to all the Australians who follow this website!) Thin out the trees on your southern exposure to maximize the sunshine hitting your garden. Since the light of the sun is greatest around the equator a garden receiving a southern exposure will get the most light. (Here are some tips for designing a raised bed vegetable garden)

Raised Beds oriented east to west.

The sunlight travels east to west so orient your garden to maximize that exposure. This is also important when it comes to your garden bed orientation. You want the length of the bed to go from east to west otherwise the plants in your bed may cover other plantings and shade each other more. You also want the taller plants to be on the north side of the garden beds so that they don’t shade out the smaller ones. Unless that is your goal. Maybe you want to use the shade to extend the season for shady vegetables?

Just because you have a shady garden doesn’t mean you can’t grow a vegetable garden, it just changes the types of vegetables you can grow. Leafy greens often grow very well in shade (although a little slower than in the sun). The advantage of shade for leafy vegetables is that they can stay cooler in the summer when typically they will bolt (go to seed). You can still grow your chard, kale, and lettuce in the shade. If you have a shady area or two in addition to your sunny vegetable garden you can transition to growing leafy greens and extend your season by utilizing your shade.

Spinach is one of several greens that can grow in shade.

This year in my garden I’m planning on some potted plantings of leafy greens that I can start in the vegetable garden then move to the shade garden as things get warmer.

Vegetable Garden Plants that Can Tolerate Shade:

Arugula, Chard, Leeks, Lettuce, Kale, Mustard Greens, Spinach

Light is one of the most important parts of your garden plan. Make sure you consider it when planning out your plantings and think for the long term. Not just this year or next, but 10 years done the road. One thing is always true, everything changes!

Garden Tour Video April 13, 2020

The shade garden appears in this video.