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Caring for Annuals and Perennials

May 24, 2023
Written by Aaron

You’ve selected your annual and perennial plants, chosen their location in the garden, amended the soil and everything is planted. Or close to it!  Now what? How can you take care of them to maximize their potential?  A bit of simple and easy maintenance will keep your plants healthy and blooming.

Once they start blooming, most annuals will flower all season long, until cold temperatures or frost put an end to their display. Many perennials will bloom for several weeks. We listed some of our favourites in this article if you missed it.

Here are some simple tips to keep your plants looking great!

Water

Newly planted annuals and perennials, even drought tolerant plants need to be watered at planting time. 

Perennials will need water every week for the first two weeks and during periods without rain. Most perennials do well with a minimum of one inch of water per week.  

Water is absorbed through the roots, so water the soil and not the foliage. Low (pressure) and slow (volume) allows water to adequately soak into the soil instead of running all over the place! It’s also best to water in the morning rather than at night because foliage that stays wet all night is susceptible to rot and foliar diseases. 

Annuals planted in containers will need to be watered more frequently than annuals in a flower bed. Hanging baskets and planters will most likely need water daily, and in the heat of summer twice a day. For hanging baskets, the water should run out of the bottom. 

In planters or the garden, use your finger in the soil to test it out - if it feels dry, your plant needs water.

Mulch

Mulch is always a very good idea to maintain soil health in the garden no matter what you’re planting!

An organic mulch will help enrich your soil, and keep it moist. A layer of at least 2 inches of mulch will also suppress weeds. Who doesn’t love that? The only caveat: don’t allow the mulch to touch your plants.

Deadhead

Deadheading or removing flowers that have finished blooming is important for many plants. Doing this allows the energy from the plant to be sent to producing new blossoms in annuals, and some perennials.  

How do you do it? Take sharp, clean scissors or pruners, and cut off any dead flowers just below the base of the flower or above the first leaf. With some plants you can simply break off the spent flowers.

Bonus: your plants will look much better without dead flowers on them! 

Note: some annuals don’t need deadheading. For example, Verbena, Lantana, Lobelia, Impatiens, Petunias, and Begonia.

Fertilizer

Let’s face it, fertilizer packaging can be confusing. They often feature three letters and three numbers. What does it all mean? What is N-P-K? This Eising article explains all you need to know about fertilizing and is worth the read. 

However, in a nutshell, this is a really easy way to remember the function of N (nitrogen), P (phosphorous and K (potassium) when it comes to fertilizing. The numbers are the percentage of each of those nutrients that the fertilizer package contains. 

N = UP - foliage and blooms

P = DOWN - roots

K = ALL AROUND - overall plant health

If you used an organic, slow-release fertilizer when you planted your annuals or perennials in the ground, you shouldn’t have to fertilize again during the season. 

Most potting soil in planters or hanging baskets contains the nutrients needed to help your plants get started. An easy way to maintain nutrients throughout the season is sprinkling Shake n’ Feed Ultra Bloom 10-18-9 slow release fertilizer on top of the soil. It will slowly  feed your plants for three months.  For heavy feeders like petunias or plants that are hungry, looking light, and in need of an instant boost, use a water-soluble fertilizer with an NPK ratio of approximately 20-20-20 every two weeks to keep them blooming. 

For perennials, trees and shrubs that need more nutrients during the year, Shake n’ Feed slow release 18-6-12 fertilizer can be applied in the spring and it will feed your plants for three months during the growing season. The same fertilizer can be used for trees, shrubs and perennials in subsequent seasons.

As a rule of thumb, it’s better to under-fertilize and watch how your plants respond. Over-fertilizing can lead to sick plants that have yellow or brown leaves. In your garden, the only way to know what your plants need is to test the soil. Otherwise you’re guessing! To test your soil in Ontario, samples can be sent to The University of Guelph.

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