In the Garden This Week: More Favorite Perennials

(First,  let me mention a lecture that URI Master Gardener Hall of Famers Lucy Huggins and I will be giving at the Middletown Community Garden (behind ther Middletown Public Library) THIS SATURDAY, 28 July at 10 a.m. Our topic is "Water Conservation in the Garden." In case of rain the lecture will be inside the Library. This is a very important topic for all gardeners and the lecture is open to the public and free.)

Now let's consider a few more favorite perennials for our garden. I want to discuss three of my personal favorites which require special attention. But the rewards of a few extra steps are truly exceptional.

Dahlias have been a great garden favorite for many, many years. They have been described since the end of the 18th century. (My grandfather was a commercial dahlia and gladiola grower). There are many reasons why these flowers are so special. First, they come in an almost total rainbow of colors along with some that are bi-color. Think of a color (except blue) and you will find a dahlia color you enjoy. My particular favorite is Thomas Edison, a deep, deep purple color. Especially prominent in the perennial garden are the dinner plate dahlias, some with a flower that is as much as 11" in diameter. There are also cactus dahlias which have many small spiky petals. They also come in many different colors but the bicolor ones are particularly attractive. Also the small-sized dahlias are nice for edging a flower bed. Dahlias do not need much care once they start to grow, other than possibly staking them. They need to be deadheaded as the blooms die off; but this will provide stimulation for other buds to form and grow. If dahlias are planted after the last frost in the spring, they will bloom around July and keep blooming until frost in the fall.

Another dramatic perennial is the Canna. These seem to work best when they are planted in containers or in the center of a small garden bed. Canna is a tropical plant which has huge leaves that resemble banana leaves. Like the dahlia it prefers full sun. I am growing one this year that is three feet+ tall, but it hasn't flowered yet because I was late in planting it. Mine have beautiful orange and yellow flowers when they bloom. There are some cultivars of canna that will grow to 10 feet in a single season. This plant requires little maintenance beyond initial fertilizing and perhaps an added mid-summer fertilization. They also need to be deadheaded as the flowers fade. 

A very special perennial known for its very interesting flower is the Calla Lily. This is a special favorite for some wedding florists. It has the most delicate flower and it comes in white, yellow and various shades of purple and pink and a few other colors. A group of Calla Lilies naturalized (placed close together in a small bed) makes for a very pretty arrangement.

Now for the extra care: None of the above flowers are acclimated to our year-round weather conditions. Recently, by the way, the newly-issued US Department of Agriculture hardiness map has put most of Aquidneck Island in zone 7a. If these flowers are left in the ground over the winter they will freeze and their bulbs (from which they spring) will rot. If we were to continue to have the moderate conditions we had last year, without a hard frost, they might survive. But that winter of 2011-2012 was probably a little abnormal.

So what to do: Yes, you have to work in the fall around the time of the last frost (usually mid to late October). Many gardeners are tired by that time and they feel these plants are too much trouble, but a little work in the fall will enable these perennials to significantly increase in number from year to year.

Here is what you do:

1. After the first frost, dig up the bulbs of the flowers.

2. Trim off the dead leaves and stalks and put those in your compost pile.

3. Hose off the bulbs and remove any bulbs that are broken, in pieces or very soggy. Remove the soil stuck within the bulb carefully.

4. Let the bulbs dry for a day or two in the sun.

5. Store the bulbs in a box, in peat moss or newspaper, in a cool, dry space in your basement or garage. It should be a space that get a temperature no more than 50 degrees in the winter.

You can check them once or twice during the winter and if they are shirveling or getting really dry, you can spritz them with just a little water.

Our usually predicted last frost date here on Aquidneck Island is May 15th. After that you can take them out and they will be all ready to plant and enjoy during another summer. The dahlia bulbs can even be divided at that time. Be sure to put a stake in the ground where you plant them so you will remember where they are.

Enjoy these beautiful, colorful flowers every summer.

Don't forget to stop by our gardening information and soil testing kiosk on Sunday at Paradise Valley Park (rain or shine) between noon and 2. Bring us a sample of a problem or just come to talk to us about the joys of gardening. Contact us at gardeninginformationri@gmail.com.

And don't forget the "Water Conservation in the Garden" lecture this Saturday at the Middletown Community Garden at 10 a.m.