Have you ever gone to the grocery store for, say, milk, and left with a cartful of impulse buys? Well, I visited a couple of nurseries recently in search of one specific plant and left with nearly everything except that plant, which both retailers had sold out.

As usual, I was seduced by the colorful, pre-planted annual containers on display, and hemmed and hawed about whether I should buy them or make my own.

I often do the latter, but sometimes can’t resist the allure of all that beautifully arranged eye candy.

Those thoughtfully planted pots and baskets are often created by talented garden center workers, sometimes following recipes provided by the plants’ wholesale nursery growers. They’re a great option if you’re looking for instant gratification, which, if I’m being honest, I often am.

However, creating your own mixed container is an easy, fun and often money-saving project that will reward you with flowers and pride all season long.

I’d love to tell you that you’re limited only by your own tastes and desires, but the truth is there are some killjoy considerations that need to be taken into account when selecting plants.

You’ll need to consider the mature sizes and aesthetic coordination of the plants you combine in a planter, and ensure they all have the same watering and sunlight requirements.

Choose a pot or window box that will accommodate plants when they’re fully grown, and make sure it has holes in the bottom for drainage. If not, poke or drill the holes.

Never use garden soil in containers. It’s heavy and too dense for young, tender roots to grow through. It also may contain weed seeds, or harbor fungal spores, bacteria or viral diseases that can kill plants.

Instead, use a prepared potting mix that’s formulated for the types of plants you’re growing. Or make your own by combining:

One-third peat moss, coco coir or rice hulls (if using peat, add ¼ cup of garden lime per 6 gallons to balance the pH of your final product);

One-third compost;

One-third vermiculite (replace with perlite if planting succulents, cacti or other plants that require quick-draining soil); and

A slow-release, balanced fertilizer (read the label for dosages).

For lush, abundant container arrangements, the traditional recipe includes a cute, rhyming threesome of plant types: thrillers, fillers and spillers.

Thrillers are tall upright plants intended to draw the eye upward. Plant your thriller first, placing it in the center of the container.

Surround the thriller with fillers, which are shorter plants that will spread to fill in the space between the thriller and spillers.

Spillers are vining plants that will cascade over the edge of the pot as they grow. Place them just inside the perimeter of the container.

If your potting mix doesn’t contain nutrients, apply a fast-release fertilizer right after planting.

Plants growing in containers will need more attention than their in-ground counterparts. That’s because plants growing in the garden can spread their roots far and wide to reach distant nutrient and water resources. Potted plants are limited by the contents of the container, so they’re entirely reliant on you.

Soil in containers dries out much more quickly than in the garden. Sometimes I water pots in the morning only to return to wilting, thirsty plants at night. Check them twice a day, especially during hot, dry spells.

Follow fertilizer directions for potted plants; typically they recommend more frequent fertilizing than for beds and borders.

Got questions about gardening? Please send them to Jessica Damiano at jessica@jessicadamiano.com with “Gardening Question” in the subject line. She’ll answer selected questions in a future gardening column. Damiano writes regular gardening columns for The Associated Press. She publishes the award-winning Weekly Dirt Newsletter.