Spring is usually the best time to purchase and plant perennials (although hardy perennials can be planted in the fall, much like bulbs.) Growing perennials from seed is inexpensive, especially if you want to cover a large area. However, most perennials are now sold as plants; more mature plants make planning your design a bit more accurate and in general makes planting easier.
Most plants bought in spring have been vernalized (gone through a winter dormancy) and will establish easily. Plants bought in late season have not, so get them started before frost hits, but a large portion of fall energy goes to the roots, so this is a good time to start perennials (nothing tender) and get a jump on next year. Look for plants that have signs of new growth and avoid plants with any sign of disease or pests.
Planting a Perennial Garden
Expert tips about soil, fungi, and weeds for a beautiful garden
How to Choose When to Buy an Established Perennial or a Smaller One
Although you can leave perennials in their pots for a short period of time, plant them as soon as possible to avoid drying out or getting root bound. There is a movement in the wholesale trade to larger pot sizes for perennials and this seems to have polarized the perennial world into the “It’ll grow that size in a year or three” camp and the “Time is money, and I want instant effect” faction. If the plant is going to sit around in the pot at all, spend the money for the more established plant in the bigger pot. I fall somewhere in between the warring factions; there are some plants I will always buy big (coneflowers, peonies, grasses) and some I will always buy small (thymes, asarums, most any groundcover types). A 1 gallon can is my middle of the road container; I’ll go up for the former list and down in size for the latter list.
Prepare Soil First
Because perennials are a permanent fixture in the garden, you should take some extra time and care in preparing the soil as you won’t have this opportunity again. Sandy soils can be improved by adding organic matter. Some of my favorites for amendment are compost or mushroom soil as they both have good organic fertilization assays. For those without access to a good compost pile or mushroom soil, these can now often be found bagged in garden centers, or may I recommend cocoa mulch.
Cocoa Mulch for Perennial Soil
I originally started using cocoa mulch as an additive to my bonsai soil and noted the quick breakdown and resulting deep, dark organic matter it contributed. I had also tried it as mulch before and found it developed fungus with regular watering. While that may not sound like a good thing to many gardeners (and it certainly makes cocoa unsuitable as a mulch), it is an admirable trait if you are choosing which fungi to introduce; more on that in a moment.
Manure for Perennial Soil
Manure is an old ally in the garden but it must be composted; fresh manure has high fertilizer assays and breaks down at such a high temperature that if it doesn’t burn it one way, it’ll burn it the other. The ancient practice of hot-bedding has fallen out of favor, but a deep layer of fresh manure is covered with soil, the plants are set on that and then filled in around with a good soil mixture. This allowed gardeners to cheat a zone or two out of their gardens and you cold-weather gardeners with access to a big pile of poop should maybe think of reviving the practice (as my old granny used to say, “Take deep breaths and the smell goes away quicker.”). Besides to the true gardener, that is simply the smell of success…
How to Prepare Clay Soil for Perennials
For clay soils, add compost with perlite or sand. Most perennials need good drainage, so you may want to plant in raised beds. For the kind of clay soil that we call “bathtub” clay soil (when you water, the hole you dug for your perennial turns into a bathtub), I feel the best course of action is to use the plants that are time tested in clay conditions. I turn instinctively to the prairie plants of North America (echinacea, rudebeckias, filipendula, etc.) as the plants I just listed not only tolerate that situation, but help alleviate it by sending down a deep taproot that helps break up the bottom of the “bathtub”. If you are using sodbuster perennials like these and providing rich, organic mulch on top, which attracts worms that will further break up the soil; you will improve your soil structure with very little elbow grease on your part. Remember, it’s not hard work, its smart work that builds good gardens.
Remove Weeds Before Planting
Clay or sand, it is imperative that you remove the weeds and lawn from the bed before planting. I usually till a bed when I first create it to encourage root development; it also drags up ancient weed seed that has been lying in wait, sometimes up to a century! (That is why this is the only time I roto-till).
Getting out the weeds that are there is fairly easy and, for me, calming, meditative work. It is the weeds of the future that are the big problem; how to stop those seeds from germinating? There are products like Burnouticon that work in six hours, and kills roots with a second application- yet are safe for kids, pets, and the environement. For the more organically inclined, seek out a good Flame Weedericon. Many professional organic gardeners use them, they’re earth-friendly, and can be used on icy walkways in the winter.
Alternatively, you can seek out corn gluten. This product is becoming more available, and it does a great job as long as you keep up the applications, roughly once every three months or so. It’s worth it to me to keep my garden pollution to a minimum. Just be careful that you’re not trying to raise ANYTHING from seed in that bed; the gluten will knock it out of the picture…
How to Transplant Perennial from Pot to Soil
Once your soil is prepared, dig a hole that is just deep enough to accommodate the roots. Water the plant before removing from the pot. To remove the plant from the pot, turn the pot over and let it slide out onto your hand, tapping the base of the pot if need be. Don’t try pulling the plant out of its pot by the stem as you may damage the plant. If the roots are tightly coiled, they may need to be gently loosened to encourage outward growth. Place the plant in its hole so that it is at the same level with the ground as it was in its pot. Fill in around it with soil and water thoroughly. Mulch the area with compost or pine needles in order to deter weeds and prevent loss of moisture.
Beneficial Fungi are Good for Perennials
I had mentioned about adding our own beneficial fungi to the soil. You can do this either right after mulching or just before; I normally do it before but if it happens later, no big deal. More and more, beneficial organisms like mycorrhizal fungi are becoming available to the home gardener. Discovered in the late 1800’s and pretty well documented by the 1930’s, these symbiotic fungi were lost in the rush to “modernize” the garden (i.e., dump chemicals all over it). Fungus was a bad guy that we could kill off with the latest wonder product, not something to be promoted, and the research went dead for years. But with the renewal of organic practice to the garden scene, mycorhizii have again started to gather attention.
Simply put, mycorhizii are different species of fungi that help a plant with different tasks; some help with water uptake, some with making fertilizer available, some with gas exchange, etc. They require organic content in the soil, but in exchange help your perennials to grow and flourish (Keep in mind that some strains are better for flowers, some for shrubs, some for evergreens, so make sure you get the right strains).
The other benefit to introducing beneficial fungi to the soil is that it leaves no room for the bad guys like phytophtera or botrytis (this is known as “biological counterculture” in scientific circles). A fancy way to say, “no room at the inn,” but any way you say it, mycorhizal supplementation is the way to really modernize your garden and take care of the environment as well. You must feed and care for mycorhizii, but they like the same things your plants do, so if you water and fertilize regularly, your soil flora will stay as healthy as your garden flora.
Soil is the most basic building block in the garden, and half your plant spends its whole life down there. Make sure it gets a happy home and you will be delighted with the half you can see…