Copyright © 2005 Tammy Clayton
The end of Februrary already? My how time does fly! The sun has already become more readily available than in past few months. Perhaps more cold and clear, but those candle-hours are important to sleeping natural world; it is their built in clock. You cannot lie to a plant, it knows what time it is. Far more intelligent than one gives them credit for.
As you plan what to add to your garden this winter, I am sure you are paying attention to light and water requirements all good perennial vendors attatch to each entry in their catalog. This is very important to your success with each plant. But it is possible to mix more drought loving plants with those that require more moisture in same planting with good results. The secret lies in substructure of each given plant's area in bed.
Drought lovers do like some water, they will reward you with a much more beauty with some weekly water...in a drought bed. But what if you want to put say - lavender and phlox in with lobelia and ligularia? Those water requirements can really hamper one's creativity! So some knowledge of drainage engineering will give you ability to try mixing them in same planting area. Lavender and Phlox like drier conditions. Not that Phlox will die in a spot where daily overhead watering is recieved. It will survive and grow huge, and flower excessively, but be stricken with fungus that makes lower leaves yellow, icky looking and then become half defoliated. Ground watering is it's preferred daily moisturizing treatement. One can place it in a corner sprinkler doesn't hit and water that section by hand once or twice a week and it will reward you very nicely indeed. Since Phlox is rather tall, this avenue of placing it in back corner works out well. It likes moisture but not on its leaves. Roses fare better this way as well, especialy since one cannot control what heavens will pour down. Less black spot and such other marring problems will occur, if ground water is used vs. overhead.
Lavender on other hand loves it hot and dry. It doesn't mind what heaven pours down IF there is a good drainage structure where roots are. Too much water retention and it will slowly die. To conteract good soil water retention where one would like to plant ever so beloved lavender row, a blind drain is required. It is called "blind" because on surface you do not know that it is different from rest of area. In a planting area that is scratched once or twice a month some of substructure will mix into top surface and change color of topping soil. But once bed fills no one will see this. (Surface scratching, by way will put much needed air tunnels to roots, create more water availability to roots, and lessen amount of weeding one must do, if it is done twice a month.)
The smaller particle size of soil, moisture it will retain. Clay having most minute pieces and sand having largest. Each person's garden area will have a totally different soil structure. If you are in hard clay, I would advise that either you excavate 6" of clay and fill with 7 inches of peat/topsoil 50-50 fill OR raise bed at least 6 inches above harsh environment of clay. Raising it is much less labor than excavating! Not too many things will do nicely in clay. The only way around it is correction. Once you have nice workable soil, with good moisture retention, yet good drainage - you can go about planning what goes where and how to amend each area for certain plants.
To get good drainage, you need to go down at least 4-6 inches, depending on plants requirements. SHARP drainage is engineered with pea gravel in a 2" layer, followed by 2" of coarse sand, topped off with 2" of your rich garden soil. In times of extreme moisture worst of it will lay in gravel bed. The gravel there also holds more heat than moisture retaining soil, therefore using warmth to do away with excess water faster. Variegated irises planted with a bed of road gravel 4" beneath surface will grow three times more lushly than those in average garden soil - they love that heat! Heat and drought loving plants are much happier in that environment when regular water is recieved. It is retention that causes decline and not what comes from above. More moderate drainage would be created using 3" of sand and 3" of soil on top. Since each plant has different needs, your engineering of drainage will require a bit of working on. But it opens doors to what you can put in a planting as happy bedfellows that no drainage field would never allow you to attempt.