Answers to your questions: dahlias, spruce trees, and avocados

Premature Dahlias

Question

I planted my dahlias too early. I find that they have grown too long and seem fragile. The planting period is only at the end of May. Can I cut them back without killing them?

Answer

It’s never a good idea to bring plants indoors too early, whether they’re bulbs or tubers like dahlias or seedlings. Overripe plants become spindly (leggy), with long, weak stems. It’s better to have plants that are a little too young than too mature.

In the case of dahlias, however, pruning now will help. Cut the plants back to about 6 inches (15 cm) above the ground. This will force the plant to produce new stems that will be shorter and therefore easier to handle and less likely to break when you transplant the plant into the ground.

Pruning of “Dwarf Conifers”

Question

I have a conifer (Picea pungens ‘Fat Albert’) that I planted three years ago. When I planted it, it was about 70 centimeters tall and 35 cm wide (28 by 14 inches). It is currently about 1.5 m tall and 55 cm wide (60 by 22 inches). Its new shoots have beautiful blue-green needles. I would like to slow its growth and keep it to a maximum of 1.8 to 2 m (approx. 6 feet). How should I go about pruning it properly? Should I cut the leader periodically to prevent it from growing taller, at the risk of causing it to grow several leaders? To restrict its width, should I pinch out a few buds from the new shoots on the side branches?

Answer

Here’s the controversy surrounding so-called “dwarf conifers”: they grow throughout their lives and therefore eventually stop being small and cute. In fact, most of them easily exceed twice the dimensions indicated on the label.

Yes, you can control the size of your plant by pruning it. When it reaches the desired size, start pruning the new shoots each spring. Cut them back by two-thirds to minimize growth. This should be done while they are still tender to the touch and pale in color. Normally, the plant will retain its broad pyramid shape fairly well, but if, after a few years, you find that it is becoming too rounded, leave the shoots (the plant will tend to produce several now that you have removed the original) a little longer than the side shoots.

Avocado Plant in Decline

Question

Last summer, I germinated an avocado pit and, miraculously, managed to grow a plant. What a joy! Then autumn and winter allowed me to watch the plant grow: two leaves, four leaves… But this morning, I discovered brown spots on one of the leaves. When I touched the leaf, it fell to the ground. Should I give up on my plant? Could this be a temporary illness? I only used potting soil, a little fertilizer, and not much water (once a week). I took great care of this plant, but did I make a mistake?

Answer

The avocado tree (Persea americana) is a large tree found in the American rainforest. Seeds taken from the fruit can be germinated and grown indoors, but the results are rarely very satisfactory in the long term: our homes are too dark and the air too dry for the plant to really thrive. Furthermore, despite the pleasure you may get from germinating a young avocado tree yourself, it does not grow into a very attractive plant, tending to produce a long stem with relatively few leaves, and even if you pinch it back regularly, it will be reluctant to branch out.

Avocado tree foliage can turn brown for several reasons: air that is too dry, excessive or insufficient watering, excess fertilizer, lack of light, and more. However, as long as new leaves appear to replace dead or dying leaves, this is not a serious problem. It is important to accept that an indoor avocado tree will always be more of a “conversation piece” than a thing of beauty.

---

Larry Hodgson has published thousands of articles and 65 books during his career, in French and English. His son, Mathieu, has made it his mission to make his father’s writings accessible to the public. The text was originally published in Le Soleil on May 26, 2012.