Garden Word of the Day
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We’ve all heard of collard greens, but what if you could grow these healthful leafy greens year-round? It ends up you can.
There are several types of tree collards. The two most common are tree cabbage or tree kale (Brassica oleracea var. acephala) and Jersey cabbage (Brassica oleracea longata). These cousins of broccoli, Brussels sprouts, cabbage, cauliflower, kale, and kohlrabi are not annuals that must be replanted each spring. Instead, they are perennials. And they lack the oxalic acid that makes other members of this group taste bitter.
Tree collards description
Instead of shrub-like mounds of kale or collard greens, these tall stalks look something akin to a palm tree. They can grow 8–10’ tall, but most people trim them to half that height to keep them bushy and less likely to fall over. Tree collards grow as a single stalk with a crown of large, purplish-green, edible leaves. The more purple you see, the sweeter they taste. Stems often have a white, powdery coating that is said to reflect damaging summer sunlight.
These shrubs can live for 20 years but are most productive when replaced after 4 or 5 years. Tree collards can withstand winter temperatures as low as 20°F (-7°C), but they grow best in USDA Hardiness Zones 8–11.
How to grow tree collards
Tree collards are best grown from certified pest- and disease-free rootstock, planted in either spring or autumn. These plants are sturdy and do not require special treatment once established. If you know someone who already has tree collards, ask for some cuttings. Cuttings should be 4–6” long and about twice the diameter of a pencil. This method requires daily light watering and can take 4–8 weeks, so don’t give up. Tree collards can also be grown from seeds.
While tree collards prefer growing in the ground, you can also use a large container that is at least 15 gallons in size.
Where to grow tree collards
Tree collards should be three feet apart. And they will readily cross-pollinate with other members of the cabbage family. Tree collards grow best in nutrient-rich, slightly alkaline soil.
Tree collards thrive in dappled shade and prefer protection from afternoon sunlight. They do not grow well in full shade.
Tree collards are relatively drought tolerant but perform best in well-aerated soil with regular mulching and top dressing. And they’ll grow bigger and better with regular irrigation in summer. It’s always a good idea to have your soil tested by a reputable lab before fertilizing. Adding too many nutrients can cause more problems than nutrient deficiencies.
Tree collards pests and diseases
These plants are relatively trouble-free. Imported cabbageworm butterflies are the primary pest of tree collards. Handpicking the caterpillars and extermigating the eggs are your best control methods. Snails and slugs are less of a problem than seen on their shorter cousins. And aphid infestations tend to be localized and short-lived. Let the ladybugs and other beneficial insects take care of those pests for you. Ladybugs won’t be able to do anything about the deer and other herbivores, though.
Powdery mildew is a common problem for tree collards, so maintain good airflow and keep your plants healthy.
To keep your tree collards attractive and productive, it’s a good idea to prune out stems as you harvest leaves. If you want your tree collards to reach full height, you may want to stake them upright. When growing naturally, they tend to fall over, creating an arching tangle similar to a blackberry bramble.
Natural Root Grafts
We’ve all heard social networks help us to be healthy and successful. It ends up that trees have been networking quite intimately for a very long time.
Tree networking takes two forms. They frequently share nutrients indirectly, using soil microorganisms as go-betweens. And they fuse their root systems in natural root grafts, called anastomoses.
How do roots graft?
Natural root grafts occur when relatively small roots of two different trees come into contact with each other. As they grow, they fuse, creating mutually accessible cambium layers and vascular bundles that allow them to share water, nutrients, and the products of photosynthesis.
Why does this happen?
More than 150 plant species exhibit natural root grafts, according to researchers. There is debate about whether this occurs due to overcrowding or if plants purposefully graft their roots onto neighboring roots. There is also debate whether this action is beneficial or verging on parasitism. Most researchers lean toward the mutually beneficial explanation. Potatoes and strawberries frequently graft their roots onto neighboring plants of the same species. Surprisingly, some natural root grafts are between different species.
Benefits of natural root grafting
Natural root grafting provides several benefits to all parties involved. Those benefits include improved stability and water and nutrient sharing. These benefits help keep neighboring trees healthy, making them more resistant to wind and herbivore damage. In one study, trees with natural root grafts were found better able to recover from a spruce budworm attack.
Tree root grafting allows groups of trees to share water and nutrients. It also forces them to share soil-borne pests and diseases, such as Dutch elm disease and apple proliferation.
For me, this is yet another example of the amazing processes going on underground. I was stunned to learn that plants can hear. I wonder what will be discovered next.
Drinking and drought
Summer BBQs often involve a spilled beer or two, but did you know that might be helping your drought-impacted plants? Read on!
Climate change and food production
Climate change is having a growing impact on food production worldwide. [Sorry, I couldn’t resist.] Not all of our groceries grow well in these rising temperatures. And drought is reducing crop yields all over the place. Scientists estimate that corn and wheat crops will be seriously affected by 2030, so a lot of research is being done to see if bigger root systems or other modifications can help plants grow with less water and in higher temperatures.
Plants respond to heat
When plants are hot and dry, they protect themselves by closing pores found on the underside of leaves. These stomata control the rate of gas exchanges used by plants in photosynthesis. This respiration can be slowed by as much as 50% during periods of extreme heat. Unless your plants are drunk.
Pints and plants
Recent research has found that many plants can thrive during drought if they are given ethanol. Ethanol is alcohol. It ends up that plants produce alcohol when they don’t have enough water. This fact led some researchers at the RIKEN Centre for Sustainable Resources Science to wonder if the same processes could be used to protect plants.
Alcohol abundant and cheap to make. Did you know that U.S. bars mark up their alcohol by an average of 400-500%? But back to the plants.
Researchers compared wheat and rice plants that had been treated with alcohol to those without. The plants were deprived of water for a couple of weeks in summer. Only 5% of the untreated plants recovered, while 75% of the alcohol-treated plants were able to resume growing once watered. Those are some significant numbers!
The scientists radio-tagged the alcohol so that they could see where it went within the plants. Plants that were given alcohol started behaving like they were in a drought even before the water was cut off. This helped them to be better prepared than their teetotaling brethren. Not only did they make better use of the water they had, but they also used the alcohol to create sugars to provide themselves with energy and perform more photosynthesis, even though their stomata were closed.
Now, this doesn’t mean you should go around giving your pumpkin plants shots of tequila. That would be a bad idea. What it does mean is that an occasional spilled beer might not be such a bad thing and we should all be on the lookout for more specific instructions as the research continues.
You can grow a surprising amount of food in your own yard. Ask me how!
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