It was the best of microclimates, it was the worst of microclimates.

Picture this: you purchase two of the exact same plants, and plant them on either side of a walkway. They look great. You’re excited.

Skip ahead three years. One is growing with reckless abandon and looking great. The other one … not so much. They’re less than two metres apart, and one is inexplicably struggling while the other thrives. Why does this happen? Let`s troubleshoot.

Sunlight

What are the light needs of your plants? Are they tolerant of full sun, part shade, or do they prefer all-day shade?

Perform a little experiment with your two plants one day. When does the sun stop hitting each of them? Is there a difference?

Let’s pretend for a moment that one receives sun from 12-7 pm, while the other one receives sun from 2-7 pm. It doesn’t sound like much, but over an entire growing season that’s a difference of around 400 hours (or just under 17 days) of sun.

Many plants are able to adjust to such differences in light, but over an extended period of time you may begin to notice these differences. Perhaps the plant that receives less light is growing a bit taller as it ‘reaches’ for more. Perhaps the plant receiving more droops quickly if a watering is missed while the other remains unaffected.

As a case study, picture A shows a row of beautiful Sun King Aralia in one of our displays. In pictures B and C, we see the difference in colour between a plant situated closer to the building and one further away. As you can see, the plant closer to the building has produced more chlorophyll to compensate for reduced light levels – leading to leaves that are green rather than bright yellow. The distance from one end of the display to the other is only four feet.

Water

Sunlight also generates heat. Added heat increases the rate of water evaporation on the surface of the soil. If one plant receives more light, over several seasons it will require significantly more water than the other to flourish.

Sunlight doesn’t just heat the soil – it also heats up your house. Your outer walls reflect and radiate heat in the hot summer months. If one plant is situated closer to a house than another, it could receive more of this heat, speeding the evaporation process. If one plant is close to a driveway or patio made of stone or asphalt, its reflected heat can also have a substantial impact on its watering needs.

Finally, if one plant is closer to the house, this could also limit how much water it receives when it rains. Overhangs and eavestroughs often prevent rain from reaching the soil immediately adjacent to the house. Trees or other large overhanging objects can of course have a similar effect.

Wind

Is one plant set further out from the house than the other? Perhaps one is sheltered by a building on two sides while the other plant is sheltered only on one side. In the summer, wind can increase the watering needs of a plant. In the winter months, evergreens that receive more wind are susceptible to damage from desiccation. If one evergreen winters beautifully, and one in a more exposed area has brown tips or branches, you’ll know what the cause is.

Final Thoughts

What we’re getting at with all of this is that two metres can actually make all the difference in the world, especially if several of these factors are all in play at once. We’ve only touched on a few of perhaps thousands of tiny little differences (soil, snow, and slopes are a few others) that can make or break a new planting. Our best approach as gardeners is to observe and adjust:

Observe the differences between the two plants in question to figure out what’s causing a discrepancy, and adjust our watering or other maintenance to remedy the issue.

Grappling with a difficult planting site? Explore our Plants For Different Growing Conditions Tipsheets for advice on what to plant or how to care for these types of gardens.