In addition to cold hardiness zones, some plant tags (Monrovia Nursery, for example) come with heat tolerance zones, which you can find on the Plant Heat-Zone Map. This scale allows you to gauge whether you can chance it in your area. For instance, I chose a Shaina Japanese maple, which is rated okay for Heat Tolerance Zones 2-8, but I chanced it in Zone 9 (see photo). I was betting that the afternoon shade and spray from a water feature would help it thrive. Five years later, it’s fine and strong, but it does look a bit sun-dried during a rare 100-degree heat spell, which burns leaf margins (edges) brown from desiccation. This could be prevented with the application of anti-transpirants. Plants rest at night, during their respiration process, and it’s actually the hot night temperatures that exhaust the USDA Hardiness Zone 3-8 plant in Zone 9. Gardens on the coast with cool night temperatures have better luck.Microclimates
Within your hardiness zone and within your yard, microclimates lurk, ready to take your young ones. Inexplicably, plants, which are supposedly correct for your area, will wilt and die or never emerge from the ground in spring. Valleys, hills, bodies of water, wind, moisture, soil, neighboring plants, pets, and the mass of buildings are some of the conditions affecting climate in your garden. You just have to learn about your area. The nursery down the street, local garden clubs, and online blogs will tell their sad stories about what happens when nature gets the best of the garden.
Sunset Publishing Co. has done a great job of explaining microclimates created by hills and bodies of water on the US west coast. Sunset created a new rating system for that area, numbered Sunset Zones 1-24, which Sunset refers to in their books. These numbers are not used on plant tags and we will not use them in Garden Railways
, which has a global readership.
In the last photo, microclimates in this yard include high-and-dry slopes, sun-baked stacked rocks, deep cool shade, high-traffic hardpan, low boggy spots, wet pools, and maybe urine-soaked soil near dog runs. Read your plant tags and refer to the many plant charts in Miniature Garden Guidebook
to identify which plants might fill the needs of those problem areas within your hardiness zone. If you’re looking for a cozy place to winter over a tender perennial, plant it near your house, where the climate is several degrees warmer due to residual heat loss. Planting season
Springtime seems to awaken the gardener in all of us and then by fall, we’re busy battening down the hatches for winter. Your plants are getting ready for winter, too. Cold temperatures initiate dormancy and the tops stop growing, but some plants continue to grow underground until full dormancy, when metabolism has all but stopped.
One last suggestion for increased winter-survival is to transplant new plants in the fall or late summer. Giving new plants cooler nights but warm days allows them to get a good start setting down roots. Be sure to distress the root ball to encourage lateral rooting. After looking at great gardens all summer you should have collected a nice list of plants to buy. Nurseries often have sales in the fall and you’ll get a larger size plant than in springtime – it’s a good deal for plants and your purse.