Planting and Planting Times


Planting will take place for xeric plants in your existing soil with a minimum of amending and loosening for the lowest maintenance garden. I believe gardens composed of only drought tolerant native plants should also have their soil worked and amended. If we decided to just mimic nature, this wouldn’t be necessary.

Depending on your soil type and condition, more or less amending will be necessary to bring about the desired results. Be that as it may, I will assume the landscape bed or border to be planted is amended soil.

Dig a hole relative to the size of the plant (since your soil is recently amended, this need not be over large). After removing the plant carefully from its container, gently shake out some of the potting mix and separate the roots if they are tight and root bound. Scoring the sides of the root ball is an effective means of stimulating root growth. A little judicial root pruning may be necessary, as well. If the container mix is peat, I try to remove a good bit of it without damaging the roots. Peat is difficult to re-wet once it dries out. Once planted, if the peat dries out in the soil, it is difficult to re-wet the root zone in the ground. You think you are watering the plant, but the water is not reaching thirsty roots. This is one cause of death shortly after planting.

For a quart-size plant, I will nearly always add to the plant hole a handful (average size women’s hand) of Soil Mender Yum-Yum mix, more for gallon containers on up, less for a 2” container-sized plant. I started this years ago and will probably always keep it up. I haven’t conducted scientific experiments or blind trials to see if it is indeed better. But I feel good about it and the plants do very well. I have greater success now after following these guidelines than I ever had. I am never surprised if all the plants live; I am always surprised if one dies.

To further reduce stress on plants, plant in the mornings or late afternoons, rather than the heat of the afternoons. Cloudy and misty days are good planting times. If you can wait until a mini-heat spell has passed before planting, your new plants and transplants will appreciate it. Water plants well the night before planting. Soak transplants well the day before, prior to digging out and moving. Watering plants in with compost tea, or aerobically activated compost tea if you have it at planting time and throughout the growing season is being done at public gardens (“Tea in the Garden,” by Allison Knab, The American Gardener, November/December, 2005). Making compost tea or aerobically activated compost tea adds planning and coordination to insure you have it on hand when you plant.

Mulch the bed immediately afterwards with inorganic or organic mulch, whatever you decide is best. If you’ve planted small, 2” container sized plants, place a paper or plastic cup over the plant for protection and shovel on the mulch. Remove the cup.

Water as needed for the size of the root zone and weather conditions. This is an all-inclusive statement. As the plant establishes and the root zone enlarges, less frequent supplemental irrigation is required. If the weather turns unseasonably hot immediately after planting, it may be necessary for you to set up something to cast temporary shade to relieve heat stress. Wind protection may also be needed while the plant establishes. It is difficult for me to give you a watering schedule. Test the soil with your fingers to determine if it is dry in the root zone.

This all sounds like a lot of work, but if you plant within the optimum planting window, everything should grow fine.

Planting Window

In beds and borders where the soil drainage and organic content is well prepared for the type of plant, there is more leeway on planting times than I previously thought. When I first started xeriscape gardening, I came to it by way of failure – failure for my garden to survive using the wrong plants in ill prepared soil. So after long thought and study, I determined part of my problem was planting outside our rather narrow planting window. That window of opportune planting came April 1st through May 15th for cold hardy perennials. I noticed that the percentage of surviving plants I planted after May 15th decreased dramatically, and most planted into June failed to survive at all. My typical plants sizes were 2 inch and quart-sized containers.

For the beginning gardener, I still recommend this shortened spring planting window. If you have just begun your soil amending or bed reclamation, most likely the soil life is just beginning to grow and multiply. Active and thriving communities of microorganisms make all the difference in a quick establishment of your plants. Soil microorganisms do much of the work, so you don’t have to.

If you have just finished preparing your beds or borders and then immediately plant, the soil life needs to “establish” along with the plant. For optimum success of cold hardy perennials, the April 1st – May 15th is the best spring planting period. Young tender plants with limited root zones need time for the root zone to grow and expand prior to the onset of summer’s day and nighttime heat, which usually begins about June 1st. If our springs continue to warm earlier, the optimum beginning date will be pushed back to March 15th and the ending cutoff may come sooner as well.

The section on Stepping Stones, my month to month gardening pleasures, details correct planting times for our climate for perennials, bulbs and vegetables, both cold hardy and warm season plants. Please refer to it for specifics.

Cold-hardy perennials can be divided and transplanted as soon as mid-March (weather permitting), and if ordered shipments arrive early, once you have hardened them off, it should be safe to plant them. Planting at the beginning of the planting window provides quicker establishment with less on-going maintenance (irrigating). This is due to cooler temperatures and the occurrence of springtime moisture (hopefully). There is less environmental heat stress – more energy goes into root zone development. I discourage myself from transplanting after mid-April, particularly grasses, which can be transplanted at the beginning of March, at the same time they are cut back. Transplanting earlier is better than later, but each plant has different requirements. With some plants, no time is a bad time to move it, others are much more finicky.

Non-cold hardy annuals and perennials for containers are best set out after May 1st (recall the 2” snowfall Amarillo received on May 2, 2005). Plants in containers are more sensitive to environmental changes than plants rooted direct in the ground. Even nighttime temperatures in the low 50º’s are too low for tropicals. The minimum chill threshold for subtropicals is 33º – 40º. To be safe, this means the nighttime lows must be above 40 degrees for subtropicals, and 55 degrees for tropicals to safely leave them outside. The chill threshold varies from genus to genus, species to species, and variety to different variety. Even minimum exposures of 4 – 6 hours are enough for irreversible damage to occur in the cell membranes. These temperatures may damage their tissue and stunt their growth that will not be able to be overcome. Damage to the plant includes slowed and delayed growth, delayed or no flowering, blackened and death of leaves and reduced water and nutrient absorption. If you have subtropical and tropical plants, monitor the temperatures closely and plan to move then back and forth, inside and out.

Extended Planting Window

Springtime is a busy season, not only in the garden, but also in gardener’s lives; often life preempts planting. The planting window can be left open longer under any of these cases:

  • Well prepared soil a minimum of 2 ½ -3 months in advance of planting,
  • Buying the perennial in a gallon or larger size container (bigger root zone),
  • Planting xeric plants,
  • A cooler and wetter June.

Any combination of these factors increase your success rate the later you plant. I now will occasionally plant a choice plant (if I notice its availability) even in mid July and expect it to survive by watching and following those guidelines. My flowerbeds and borders have had an active soil life for several years, which allow me that flexibility.

Fall planting can begin whenever summer’s heat breaks. In some years, relief comes along with Labor Day, but generally, by September 15th, it is safe to resume planting until the end of October. Again, allow enough time for root development prior to winter’s onset (but we never know when that will be). Many books and nurserymen allow for the planting of trees and shrubs throughout winter in unfrozen ground. Trees definitely need cooler weather for planting and transplanting, mid October throughout the winter and into early spring. Trees planted in summer suffer greatly and usually fail.

There is a good deal of leeway on planting bulbs. Spring flowering bulbs can be planted from mid October through December. I usually plant blulbs Thanksgiving week in November. After that, the weather is too unsure. Summer flowering bulb planting should not begin until April 20th; May 1st is better. Summer flowering bulbs (the non-cold hardy ones) are temperature sensitive and will rot if planted before the soil has warmed.

Cold hardy vegetables can be planted as early as mid February through mid-April, then again beginning no sooner than August 15th through the beginning of October. Warm season vegetables can be planted beginning mid April through mid August.

Disclaimer: As always in the Texas Panhandle, our weather is unpredictable. Even with careful planning and adherence to guidelines, extreme or unseasonable weather can descend and nullify our best intentions.

Angie Hanna, January, 2006