Consider this weekend as a deadline and turning point in the garden. Several tasks should be completed as soon as possible, because putting them off will have disappointing results.
With the prospect of relentless heat upon us, the planting time for perennials and woodies is just about over. The disturbance of roots growing in loose commercial planting media (a necessary procedure) makes the plants vulnerable if planted in July and August and thus requires near-constant monitoring for water needs and even artificial shading at midday. (I.e., no vacations allowed.) So plant your acquisitions promptly, paying lots of attention for the next few weeks - or wait till September.
If your woodies - that's the horticulturist's term for shrubs, trees, and vines that do not die to the ground over winter - need reshaping or reduction in size, do so immediately. The new growth that pruning stimulates must have plenty of time to mature before freezing weather, or it won't make it through the winter. Azaleas and many other spring bloomers need time so they can set buds on the new growth in late summer and early fall for next year's flowers. (How to get a crummy azalea display: Use the hedge trimmer to shear the plant into a smooth ball or cube; repeat two or three times.)
Late fertilization of woodies can have the same effects as late pruning - new growth that has inadequate time to mature. If you're inclined to fertilize them, this is the last time for this growing season.
Last call to pinch chrysanthemums and asters. If they have already begun to morph from mostly vertical growth to denser, branched growth (with some mums already setting buds), you have a choice: Leave them alone and get late-summer as opposed to fall blossoming, or cut back now, with a slightly delayed fall display.
Rainfall and heat for the next two months are anyone's guess, which means staying on top of things. Some areas have received multiple downpours in recent days, others are drying out. Deep watering is always best, and remember that running the sprinkler at midday wastes water due to instant evaporation. When the top layer of soil becomes really dry and hard, a two-stage approach can help: Do a light watering that's enough to moisten the top quarter to half-inch, but not so much that it's basically running off; wait a spell (or move on to another section of the garden); resume watering, and the soil will more readily absorb the water.
Mulch to conserve moisture. Right around the trunks of trees and shrubs, the 3-inch-deep layer of organic matter should thin to nothing. The highest point of the mulched tree ring should be the perimeter, never at the trunk, so that rain and hose-watering soaks in instead of running off.
Mulch tomato plants, which will result in a bigger harvest - when the soil exceeds 85 degrees, blossoming is inhibited; mulch will keep the soil cooler. And to prevent blossom-end rot of fruit, make sure they get consistent moisture.
Replace herbs that bolted - flowered and went to seed - earlier than normal, due to some of that May and early June heat. Basil, chervil, and cilantro are quick from seeds, but for parsley, a fickle germinator, you'll be less frustrated if you can find seedlings at the garden center.
For the fall harvest, sow cabbage, broccoli, cauliflower seeds. It's too soon to plant bedding plants - wait till late July, if the garden center offers them. Last call to sow seeds of beets, carrots, and snap beans.
For best eating, harvest zucchini when they're small. This will result in a continuous crop of tender ones and prevent the conundrum of which "friend" to give a giant, low-flavor zuke.
And deadhead. (No, this is a not an invocation of Jerry Garcia's fans.) The spent flowers of most annuals need to be removed or the annual turns its attention to ripening seeds. You want its attention back on producing more flowers to replace the ones you deadheaded.
- Michael Martin Mills