First Published 3/3/2005
Juvenility

Juvenility is a growing phenomenon in the garden – and I mean that literally.

In the plant world, juvenility doesn’t refer to those times when you throw a temper tantrum because your dog has chewed up your favourite dahlia. Juvenility actually refers to how much growth a plant needs to develop before it can produce flowers. Nothing – not extra fertilizer, nor extra water, nor soothing music nor homemade remedies – will coax these plants into blooming. Only the passage of time can “cure” the juvenile phase.

Juvenile Behavior

Anyone who’s grown a corn plant knows that if you sow seed in May, you don’t expect cobs to form in June, when the plants may only be knee-high. This is because the corn must pass through its juvenile stage first.

Sometimes getting past juvenility is as simple as a matter of developing a minimum and absolute number of leaves.

Indoor plants such as clivias require a minimum of six pairs of their long, strap-like leaves before they can produce their flower spikes. Nothing can force them into flowering before those six pairs develop. The popular Wave petunias require even more leaves before they will flower – thirteen, to be precise. Several varieties of cauliflower must produce nineteen leaves before a single curd will sprout.

Some plants spend less time as juveniles than others. Impatiens flower at an incredibly small size, when the plants are no larger than a quarter in diameter – it’s almost as if they’re flowering at the seedling stage. Celosia and mimulus have similarly brief juvenile periods.

No Parallels Here

It’s tempting to compare juvenility in plants to adolescence in humans, but the reality is much more complex. With adolescent humans, we think of the entire body as being at more or less the same stage of development. But with plants, different tissues often coexist at different levels of maturity. For example, an apple tree may have juvenile suckers arising from its base, and mature upper branches that produce fruit.

There can also be a huge range in juvenility between closely related plants. Some pines will yield a few mature cone-bearing branches in their first year of growth, while others won’t produce their first cones for up to 45 years.

The Need to Know

Understanding juvenility is not just an academic exercise. Gardeners trying to take cuttings from their plants, for example, should know that both hardwood and softwood cuttings will root better if they are taken at the juvenile rather than the mature stage. Choosing juvenile over mature cuttings can mean the difference between success and failure. Moreover, if you know when to expect your plants to enter the mature phase, you’ll know not to waste water and fertilizer on them in a futile effort to get them to bloom. (Conversely, if your plants have reached what you know is a mature stage and have yet failed to bloom, you have a good indication that there may be a genuine problem.)

Other Factors

Of course, with many plants juvenility is far from the only factor that determines when flowers will appear. Day length, sunlight intensity, and temperature are just some of the other factors that come into play as plants struggle to leave their juvenile days behind. In this way, at least, plants are like people – sometimes they just need time to get past their juvenile phase before they can really blossom.