There are ways to tell if you’ve overwatered a potted plant. If it sends up a periscope and a white flag, you’re keeping it too wet.

Many of us bring outdoor container plants indoors for the winter and then return them back outside again once the weather warms. We can help our wintered plants prepare for another outdoor growing season with a few simple tips.

Plants that are easily brought indoors and overwintered include geranium, begonia, mandevilla, gerbera daisy and hibiscus. There are ways to winter several of these by letting them go semi-dormant in a cool, dim location, but keeping them actively growing in a sunny window or under lights works well for most of us.

After winter’s short days and weak sunlight that’s low on the horizon, our wintered plants sense the longer days of March with its increased light intensity. The higher light level sets the stage for a spurt of fresh spring growth.

Growth that occurs on geraniums, hibiscus, mandevilla and other plants during winter is often stretched and has smaller leaves and spindly stems, all as a result of lower light.

The first step in preparing our wintered plants to transition outdoors in a few months is to remove winter’s weak growth. Mandevilla, with its pretty trumpet-shaped flowers of pink, red or white, has a vining habit, and the winter growth is often straggly.

With pruning shears, trim the whispy, weak vine growth back to a point where the growth is well-branched and strong. On average, our own mandevilla requires about one-third of the plant’s current size to be pruned back.

Pruning these plants in March or early April not only removes weak winter growth, but also stimulates fresh new growth to emerge on the plant, encouraging a strong, stocky, well-branched structure.

Hibiscus likewise appreciates a dramatic cutback. Reducing the plant’s height by one-third or one-half coaxes new shoots to form along the branches. Hibiscus plants often lose yellowing leaves during winter, and a good pruning gets them back on track.

Older geraniums with stems that have grown woody with less foliage are transformed beautifully with a drastic spring pruning in March. Cutting old geraniums back by half or two-thirds, even if no leaves remain, invigorates the geranium and fresh growth soon emerges along the stems.

Geraniums and hibiscus plants bloom more profusely on the vigorous young growth that drastic pruning creates.

Along with pruning, this is also the time to repot plants if they weren’t repotted into fresh soil last fall. If plants have outgrown their current containers, increase the pot size by about two inches, which provides an inch of space for new soil all the way around the current soil ball.

Fertilizing should also begin now, which provides the nutrition to support the new growth stimulated by pruning and higher light intensity. Water soluble types work well, following label directions, and can be applied every two weeks from now through the summer growing season.

Continue growing the pruned-back plants in a sunny window or under lights until danger of frost is likely past. The plants we overwinter are generally tropical in nature, so moving them outdoors is best delayed until temperatures are consistently mild, with night temperatures that don’t drop below 45 degrees F.

When we’re ready to move our wintered plants back outdoors to our patios, porches and decks, the transition will cause less stress and damage to the plants if we do it gradually.

The transition process, called “hardening off,” helps plants become accustomed to higher light levels, wind and other outdoor elements. Begin by moving the plants outdoors to a sheltered, wind-free location in the shade. After they’ve adjusted for three or four days, gradually expose them to filtered sun and a little more breeze for a few additional days before moving to full sun.

After a hardening-off adjustment period of about 10 days, the plants should be ready for their permanent summer outdoor home on a patio or a deck. Without a gradual transition, plants can become sun-bleached and suffer windburn if plants are moved from indoors directly to full sun and wind outdoors.

When plants are moved outdoors, they also require more frequent watering than was needed indoors.