Planting Bulbs Late in the Season

Learn about when to plant bulbs—no matter how late in the season it may be

Late this fall or even later, a certain percentage of busy gardeners will be dismayed to realize that they haven’t yet planted their flower bulbs. Rooting through the gardening stuff they will find that bag of bulbs and, with a modicum of guilt, wonder what to do with the little rascals. If this sounds familiar, take heart. For one thing, it may not be as late as you think.

Planting bulbs late

When in doubt, plant the bulbs. They are programmed by nature to grow, and late planted bulbs often still grow and flower just fine. If bulbs should be planted in October in your area and you’re looking at unplanted bulbs in December – get them in the ground. It’s not optimal, but it is certainly not unfeasible. If it is at all possible to work the ground (look for mulched beds which don’t freeze as quickly) plant the bulbs – three times as deep as the bulb is high, if you can. However, if you’re looking at unplanted spring-flowering bulbs in March or April, you’re probably out of luck. Though they look like nothing more than brown lumps, flower bulbs are actually living things. Nested inside each is a tiny embryonic flower, complete with leaves, surrounded by layers of plant food ready to nourish the bulb to bloom. All a spring-flowering bulb needs, is to be planted in a somewhat timely manner for rooting and a period of sustained cold to activate the bio-chemical process that stimulates it to send forth its glorious spring blooms.

Spring bulbs? Summer bulbs?

Flower bulbs fall into two main categories: spring-blooming and summer-blooming.

Spring blooming bulbs:

Tulips, irises, crocus, narcissi (daffodils), snowdrops, grape hyacinths, hyacinths, alliums and a whole lot more.

Summer blooming bulbs:

Gladioli, dahlias, lilies, canna, begonias, nerines and others. What makes them different? Spring bloomers are known as ‘hardy’ bulbs, programmed by nature to need a cold period before they can bloom. Not only can they survive the cold, they need it. That’s why they must be planted in the fall. Fall planting allows them time for a long, cold “beauty sleep” during which the winter’s chill stimulates their spring blooms. For tulips, for example, this translates to 12 to 16 weeks in the dark with a sustained soil temperature below 10 degrees C. In most areas, the optimal planting time is when autumn night-time temperatures dip down to between 5 and 10 degrees C. Most summer bloomers, on the other hand, are not hardy – and cannot survive sustained low temperatures. They are known as ‘tender’ bulbs. Summer-flowering bulbs are available for sale in spring and should be planted outdoors after the threat of night frosts has passed. In the fall, many people dig up summer bulbs to store them indoors in a cool dry place over the winter for planting again the following summer.

Good bulb, bad bulb

About those bulbs you forgot to plant in the fall (or spring). The best way to tell if they are still viable is to gently squeeze them. If they are firm, not dry or spongy, they are probably still okay – though no guarantees. Plant them immediately (unless the ground is frozen solid). After all, nothing ventured, nothing gained. If the ground is too hard to work, plant the bulbs in pots and keep in a cool, dark, unheated area with temperatures between 5 and 10 degrees C – conveniently the normal temperture of home refrigerators. Water them, and keep the soil moist but never soggy. After 10 weeks, bring a few pots into the warmth each week to initiate growth indoors. Or move the pots outdoors to bloom once spring begins to warm things up. Flower bulbs are among the easiest plants to grow successfully. But that ease comes with a few caveats. Planting in a timely manner is one of them.