Geranium versus pelargoniums. What's the difference?

ROSALIE J. FROM GLEN ELLEN ASKS: Is there a difference between a geranium and a pelargonium? I thought they were the same plant.

Here’s where it gets confusing, so read carefully. True hardy geraniums, also called cranesbill, are the common names. They are perennial plants that come back every year, after going dormant over the winter, and either keep their leaves (evergreen) or lose them (deciduous).

The name comes from the shape of its seed pod, which resembles the beak of a crane. The cranesbill disperses its seeds when the beak pops open, shooting seeds. Some hybrid varieties do not do this.

The botanical name for these plants is geranium. A few popular varieties you can buy at your favorite nursery are Biokovo, Cambridge Blue, Karmina and Rozanne.

Geraniums (cranesbills) have five symmetrical petals, identical in size. They have many flowers attached to long thin stems, giving the plant a wispy and wild appearance when in bloom. Most varieties are sprawling, growing low and wide, and make a great groundcover. When most of the flowers have finished blooming, you can give the plant a “haircut” mid-growing season and it might produce more flowers.

So what’s a pelargonium? In areas that are prone to frosts, pelargoniums die back or die completely in winter, so most people treat them as an annual, and replace them every year.

Pelargoniums also produce seedpods, but they don’t resemble a crane’s beak. Their seeds are disseminated when they are picked up and carried away by the wind.

Pelargoniums also have five petals, just like the cranesbill, but pelargoniums differ in that the two upper petals are a different shape and size from the rest, giving it an asymmetrical appearance. Unlike the cranesbill, which generally grow low and wide, pelargoniums have tall stems that get woody as the plant ages. Some varieties can grow up to 3 to 4 feet in the right conditions.

Some common pelargoniums for sale are Ivy, Martha Washington, Regal and Scented. They all have varieties that come in many colors. Some are even two-toned.

HENRY H. OF SANTA ROSA ASKS: I would like to plant a crape myrtle tree and a Chinese pistache tree in my front yard this fall. I am going to wait until the trees start turning color and choose the ones that have the color I’m looking for. What’s the best way to plant them?

Dig a hole no deeper than the depth of the root ball, so when you set the tree in the hole, the top of the soil in the pot will be level or an inch or so higher than the existing soil. If you dig deeper, the soil under the root ball will start to settle and your tree can sink lower as well, becoming too deeply planted. Dig the hole at least twice as wide as the width of the root ball. Doing this will help the newly developing roots grow away from the tree, and in the right direction.

Make sure the root ball is well watered before you take it out of the pot and set it in the hole. Check for girdling, twisting roots. Cut off any broken roots using sharp pruners. Set the tree in the hole, and if you can find another set of hands, have someone hold the tree straight while you fill the planting hole.

There’s no need to add any amendments if your soil is easy to work with. If not, mix a shovel full of compost into the soil before putting it into the hole.

Add a little soil at a time, tamping down as you go, to eliminate any air pockets. Once the hole his filled, make a “moat” just outside the root ball, a few inches deep. This is where the emitters will go if you’re using a drip system. If you’re hand watering, fill the moat with water, keeping water away from and off the trunk itself.

If the tree came with a stake, remove it and see if it can stand on its own. If it can’t, remove the stake and replace it with two others.

Place it in the ground just outside the root ball, and tie correctly with tie tape or rubber tape, etc. Don’t use wire.

Dana Lozano and Gwen Kilchherr are garden consultants. Send your gardening questions to The Garden Doctors, at pdgardendoctor@gmail.com. The Garden Doctors can answer questions only through their column, which appears twice a month in the newspaper and online at pressdemocrat.com.