Gardening 102: Planting and Care

Buying plants is only part of gardening (some would say it’s the fun part). Once you’ve brought plants home from a garden center or ordered them online, how can you ensure that they will thrive? Not to worry; we’ll cover the most important steps of planting, watering, mulching, and fertilizing in this second installment of our Gardening 101 series. If you missed the first part, which covers choosing the right plants for your area, you can read it here.

Planting

When planting perennials, you’ll want to dig your hole as deep as the soil height of the unpotted plant, and about twice as wide. The crown of the plant (the base of the stem where it comes out of the soil) should be level or very slightly higher than ground level. Never bury the crown of the plant.

You can probably forgo any starter fertilizer. The potted plants from nurseries and garden centers are usually planted in potting mixes that contain a slow-release fertilizer, which will continue to feed the plant for months. Instead, feel free to mix some low-nutrient organic material into the hole (like compost), to enrich the soil and improve drainage.

When installing perennials (or any other plant), it’s important to water well, so that the entire root ball is saturated. An easy way to do this is fill in the soil around the plant only partially, and then give it a good water. Once that soaks in, fill in with the rest of the soil and water again.

Watering

Watering is such an important part of plant care that it deserves its own section. The most common plant issues we see are almost always related to watering, whether it’s over or under.

When perennials are watered thoroughly, they do not need daily watering, except in the most extreme conditions. When you water, make sure that it’s soaking into the soil and saturating the roots, instead of running off on the top layer where it will be no help to the plant. A tried-and-true method is to water, and then let it sink into the ground, and then water again, and let that sink in, and water again… Over and over, until you’re sure the roots are soaked.

Most plants like to dry out briefly between waters, so give the soil time to completely dry afterward. This can take a few days to a week, depending on heat and wind. To check, stick your finger a few inches into the soil next to the plant. If there’s any moisture, the plant does not need water.

Image: It's especially important not to overwater drought-tolerant plants like this 'Dazzleberry' stonecrop (Sedum), 'Cat's Pajamas' catmint (Nepeta), and rose campion (Lychnis coronaria).

Perennials have an advantage over annuals in that they can be very self-sufficient. They generally need extra water for several weeks when they're first planted, but after they're established, they can be content with only natural rainfall. In our personal gardens in Richmond, VA (zone 7), we rarely ever water our flower beds at all. Plants in containers, however, tend to need additional water since they dry out more quickly than their counterparts in the ground.

Mulching

Mulching has different purposes in the warmer months than in winter. From spring through fall, mulch is a gardener’s best tool to help retain moisture and prevent weeds, which creates less work in the long run. Wood chips, gravel, shredded leaves, straw, and even pine needles can all be used as mulch depending on the application. Gravel is a great choice around drought-loving plants like sedum and cacti, while straw and shredded leaves can provide an inexpensive option for covering large areas.

No matter which type of mulch you use, be careful not to suffocate your plants: perennials need air flow around the crown, so it’s best to leave 3”-4” of empty space around their base. Covering the base of an active plant can stunt its growth, encourage disease, and rot the stem. Excessively deep mulch can also damage your plants, because it can suffocate the roots and (in the case of wood mulch) build up excess nitrogen in the soil. A layer of 1” – 2” inches of mulch is all you generally need.

So, what about in winter, then, when most plants are dormant? Dormant perennials -- ones that have died above ground -- can usually be mulched over. This can be beneficial to insulate tender plants and prevent frost-heaving, which uproots plants from constant freezing and thawing underground. The plants should be unburied before spring so that they have all the space and air flow they need to grow.

As always, there are exceptions to this rule: coneflowers (Echinacea spp.), blanket flowers (Gaillardia spp.), black-eyed Susans (Rudbeckia spp.), and many grasses should not be mulched over for winter because they will likely die. Perennials that fall in this category will usually have descriptions that say “cannot tolerate winter wet” or some variation.

Fertilizing

Fertilizer is a bit like candy for plants: a little is sweet every now and then, but there is such a thing as ‘too much.’ And, also like candy, it’s usually optional. Organic nutrients, like what’s provided by manure, compost, and decomposing mulch, are the “real food” of the plant world. A healthy garden that is full of worms and mulched twice a year may not need any chemical fertilizers at all to thrive. If you’d like to give your plants a boost, though, it is generally safest to fertilize an entire flower bed at once, by broadcasting a mild fertilizer like 10-10-10*.

Heavy bloomers like roses and peonies, which can exhaust large amounts of energy while flowering, may need additional fertilizer to maximize performance. These plants will have to be individually researched and treated according to the manufacturer’s directions on the fertilizer.

Some plants shouldn’t be fertilized at all, including hummingbird mint (Agastache spp., Zones 4-9), bee balm (Monarda, Zones 4-9), and coneflowers (Echinacea, Zones 4-9). These are generally prairie-natives that have adapted to grow in lean soil. When fertilized or planted in overly rich soil, these plants can bloom less, stop producing blooms altogether, or flop over.

*The numbers on fertilizers describe their N-P-K (nitrogen, phosphorous, and potassium) content. Essentially, lower numbers are milder, and equal numbers mean a balanced fertilizer.

Trial and Error

Even with the best guide, there’s one step to gardening you can never avoid: trial and error. Absolutely no gardener has gotten it all right on their first try; if they tell you otherwise, they’re lying. We’ve all killed plants, misread tags, and planted something where we knew it wouldn’t thrive but hoped it would anyway. Learning is part of gardening, and it’s an ongoing process. Remember to have fun and stop to smell the roses.