The Q&A Archives: Tropical gardening tips for SW AZ

Question: Can you recommned feeding tips for a new tropical backyard. I have hibiscus, cannalilies, queen plams, bird of paradise and pigmy dates. All are new plants as of June 05, what should I be feeding with and how often should I water to maintan good growth?


Answer: Watering depends on many factors, such as your soil type, weather, plant maturity, etc. In sandy soil, water will penetrate faster (therefore deeper) but the soil will dry out sooner. In clay soil, it penetrates slower (so not as deep) but it will stay moist longer. Young plants generally need more frequent watering than established plants. Small plants generally need more frequent watering than large (because their root systems are more shallow). As warm weather arrives, you need to water more frequently than during winter.

Use the 1-2-3 Rule as an easy method to remember. Small plants with shallow root systems, such as perennials, veggies, herbs, cacti, succulents have roots that reach about 1 foot deep, so water needs to penetrate that far. When the top 1 inch of soil dries out, it's usually time to water again. Shrubs have root systems that are 2 feet deep so water needs to soak 2 feet deep. When the top 2 inches of soil dries out, it's time to water. Trees are 3 feet, etc. As plants establish root systems, the time between waterings can be lengthened, but it is always essential to water to the same depth. So you are applying the same amount of water with each irrigation regardless of the time of year, but the frequency changes. As warm weather arrives, you need to water more frequently than during winter. A soil probe will help you determine how far water has soaked. It moves easily through wet soil but stops when it hits hard soil. If you have drip or soaker hoses, I?d suggest you let it run for 1 hour, then wait an hour or so (for the water to continue penetrating), then use a sharp stick or pointy thing as a soil probe to determine how far the water penetrated in your soil. For most areas, it's necessary to run irrigation much longer than people would think. The majority of the plant problems we see are because drip isn't running long enough. In improved soil garden beds, such as for veggies, it will soak more readily through the soil than it will in landscape settings.

Also note that sometimes water pressure on soaker hoses will dwindle towards the end, so check that all plants are receiving sufficient water. And, a layer of mulch/compost will conserve soil moisture and reduce the frequency of watering. Hope this helps. Sorry there isn't an "exact" answer! As for fertilizing, since you have non-natives, some of which are not well-adapted for the low desert, you may have to fertilize regularly, unlike desert-adapted plants which don't need fertilizer. Palms suffer from various nutrient deficiencies, so your best bet is to buy a fertilizer formulatd for specifically for palms and follow the feeding recommendations. For the others, use a fertilizer formulated for blooming landscape plants and fertilizer in early spring just before new growth starts. Do not feed now, which will stimulate tender new growth which is susceptible to frost damage. Good luck!

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