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MASTER GARDENERS: Timing is everything in the garden

Lilacs bloom along Lake Boulevard in May. (Jillian Gandsey | Bemidji Pioneer)

As I watched the clouds of butterflies and bees flitting on the "James MacFarland" lilac and then heading for the "Canada Gem" lilac, I thought of how few were present only a short time ago on the conventional lilacs.

Both these lilacs have small trumpet-shaped nectaries in their numerous flowers. In another observation yesterday I noticed that the honey berries had started to ripen. Today, cedar waxwings were diving into the bushes with no fear of people walking nearby, so intent on their gobbling. Then they headed for a "Purple Royalty" crabapple tree and started eating that tiny fruit that was so recently blossoms.

The common denominator in these observations took me back to my original Master Gardening training and the university instructor teaching basic botany. He told us that if you understand how things grow, you can make good decisions about what you do to manage plants based on timing.

Let's look at fertilizing plants. When is the best time to fertilize your turf grass? As soon as the snow melts? Just before freeze-up so it's ready for spring green-up? No. You fertilize grass when it is actively growing. In a high-maintenance, irrigated lawn where clippings are picked up, you fertilize four times: May-June after three mowings, August, September and mid-October. In a low maintenance, non-irrigated lawn, you fertilize only once in September if you allow the clippings to remain on the lawn or two times if you pick them up—in August and mid-October. Why the difference? Clippings provide nitrogen for vegetative growth, reducing the need for fertilizer. Irrigating a lawn forces rapid growth; mowing is more frequent, grass roots are shallow, and the grass uses up the fertilizer. When you mow less often, the grass roots are proportional to the height of the grass. This grass has access to a greater amount of soil nutrients and moisture; it isn't as thirsty or as needy for added nutrients.

Do you fertilize shrubs or trees after mid-summer? No, because they will start actively growing and produce vegetative growth that does not have sufficient time to harden before our harsh winters. When do you fertilize perennials? As soon as the snow melts? No, after the soil warms up and active growth of the plant has begun; a plant can't take up the nutrients until it is growing actively. Unused nitrogen can leach out of the soil's upper level where it can be used by the plant and very quickly travels to our groundwater, especially in sandy soils.

So what does this idea of timing have to do with butterflies bees, and birds and the time they return or emerge? These creatures live a very tenuous life. Food that is appropriate for them must be available when they arrive to restore their vitality after a long migration. Waxwings are fattening up on abundant fruit as they are ready to nest and feed their ravenous babies. In the case of butterflies, their life cycle involves the butterfly stage, the egg, larvae, and pupa stages. With climate change usually creating earlier plant bloom, the bloom timing can be out of sync with migration. This year in my yard I am seeing the large numbers of monarchs, swallowtails, and other butterflies enjoying the nectar of these later blooming lilacs that are flowering just in time. Many different bees and other pollinators are busy as the proverbial bee of the old adage, quickly testing each blossom for nectar or pollen. Timing is everything.