Container Gardening Tips
One of the ways my family strives to be more self-reliant is growing our own food. I try to grow as much as I can in our small space. I especially like to grow my own fruit and when I left Oregon I thought I was leaving blueberry bushes behind.
The acidic soil of the Pacific Northwest and the cool weather make it just right for growing these good-for-you edibles.
They are relatively easy to grow when given acid soils and the right growing climate. Much to my surprise, I found a Monrovia Bountiful Blue® Blueberry plant at the garden center yesterday. It is loaded with fruit just waiting to ripen in the Texas sun.
This particular blueberry has low chill requirement of only 150-200 winter chill hours.
What are chill hours? Each fruit, nut or berry has a range of chill hours needed for setting fruit. Basically, they need to be cold for a certain amount of time.
The lower the number of chill hours, the better the selection performs in warm weather areas such as the lower, coastal and tropical south.
Usually in the south, people grow rabbiteye blueberries and these only need 350-700 chill hours to set fruit. My new Bountiful Blue® Blueberry needs much less than that!
Tips to Grow Blueberries in Pots
No matter where you live you can grow blueberries in pots. Here are the container, soil, mulch, and fertilizer requirements to aid your success.
1. Blueberries produce satisfactory yields if planted in containers or raised beds with mixtures of peat moss, sand, and pine bark. This will give it the acidic soil it needs to thrive. Depending on the size of your plant, you only need a container between 12 and 18 inches deep.
2. Sandy soils are ideal for growing blueberries. If you are growing in sandy soil, drip irrigation should be provided because most blueberries are not drought tolerant. Do not plant blueberries on heavy clay soils that have poor internal drainage, which will cause root decline and poor vigor.
3. Blueberries are a low maintenance plant and are easy to grow, but they are sensitive to excessive fertilizer. Instead of one high-dosage feeding, apply fertilizer two or three times a year at low rates. Organic slow-release fertilizers are best.
Avoid fertilizers that contain nitrate forms of nitrogen, which may slow plant growth. Instead, use fertilizers with nitrogen in the form of urea or ammonium.
Check the fertilizer package to determine the form of nitrogen that it contains. The most effective and most commonly used nitrogen fertilizer for blueberries in Texas is ammonium sulfate (21-0-0).
4. Mulch is vital for growing blueberries, especially during the first 2 years of planting. It helps acidify the soil, control weeds, conserve soil moisture, and moderate soil temperatures. Apply a layer of mulch 2 to 3 inches deep over the exposed soil in your container.
Appropriate mulches include peat moss, pine straw, pine bark, leaves, and grass clippings. Do not use barnyard manure, which has a high salt content.
5. Once the fruit begins to ripen, protect your berry harvest from birds by isolating the crop. Netting continues to be the most complete and effective way to reduce bird damage in small fruit plantings. It is the most durable and with proper care, may last up 10 years. You can purchase bird netting or find something at the local fabric store. This fabric or netting is placed over the plant once the bush has stopped flowering and sets fruit.
Here’s a tip from one of my Facebook readers Cris:
“It’s pretty easy to build the soil you need. Blueberries need acid soil because they have an extremely high need for iron. Soil with clay in it binds up the iron, making it unavailable to the plant. This is the recipe I’m using in my potted blueberries: half pine bark mini nuggets, half good potting soil. Then I add 1/4 cup of acid loving food the first year…then the pine bark mulch will start to break down, naturally acidifying. I mulch with coffee grounds and fallen pine needles. Yup, I mulch potted plants. It’s especially needed for these bad boys because they are shallow rooted. Keep watered regularly.” Thanks for the tips Cris!
This particular plant that I purchased is very healthy. It has hundreds of pieces of fruit that have already set and are just waiting to ripen. There is also new growth so I will have plenty of fruit next year too.
You can buy plants online or find a plant at a nursery near you. Even if you don’t need a low chill plant like I do, there is sure to be a blueberry just for your region.
Chill Hours of Common Fruit, Nuts & Berries
Blueberry- rabbiteye 350-700
Pear – Asian 150-750
Pear – European 600-1500
Plum – European 700-1100
Plum- Japanese 400-1000
Things to Take into Account When Growing Blueberries in Pots
If the climate in your area is hot and arid consider potting tropical plants with a nutritional profile close to that of blueberries, such as the Acai palm or the blackberry jam fruit. Blueberries need those mandatory chill hours we’ve talked about (the number of hours depends on the plant variety) and there’s little you can do about it.
For really hot climates, rabbiteyes and southern highbush are the most likely to survive in the U.S. In stores, you’ll find varieties that will likely fail in a tropical climate even if we’re talking about Southern U.S. Also aim for locally adapted varieties. Check local nurseries for that.
The quality of soil can make or break a blueberry plant. Blueberry shrubs are acid loving plants so aim for a soil pH of 4 to 5.5. Above 7 pH, the plants will just start dying off. The first telltale sign is either no harvest or a severe nutrient deficiency that you can diagnose by looking at the leaves (more on that in a bit).
It is a very common mistake to (trans)plant blueberries in a garden with alkaline soil without having done any amendments first. To lower the alkalinity of the soil, just mix potting soil (with a pH no greater than 6.5 pH) with 1/3 to 1/2 peat moss, which will slowly break down in the soil and keep plants healthy.
The best potting mixes for blueberries grown in pots are those commonly sold for azaleas and camellias, two acid loving plants. Coffee grounds can work wonders too at keeping acidity at healthy levels as long as the grounds haven’t been brewed.
But the best potting mix for blueberries grown in pots is a mix that you can make yourself. Just mix potting mix for azaleas with peat moss or pine bark mini nuggets (for more acidity) and banana peel powder for a healthy dose of potassium (Check out my related post on how to make fertilizer from banana peels: DIY Dry Banana Peels as Fertilizer).
A bit of find sand is also a nice addition as it will ensure more drainage.
Bear in mind that when growing blueberries in pots, you need to amend the soil on a yearly basis as tap water’s alkalinity will lower soil acidity like there’s no tomorrow.
The best course of action is to measure the soil pH after 3 or 4 seasons and if the soil is no longer acidic, amend it with ammonium sulfate.
Also when the soil compresses in the pot and is no longer covering the roots properly, add more soil as blueberries have a shallow root system and might die if not protected by the sun.
Blueberries love direct sunlight. Make sure that you place the pots in an area where they can get 6 to 8 hours of continuous, direct sunlight.
Blueberries need tons of drainage so that the soil doesn’t get soggy. Drill lots of drainage holes in the pots (both at the bottom and on the sides). Also, before adding the soil mix to the pot, add a thick layer of pebbles to the bottom so that you don’t run the risk of clogged drainage holes. A bit of sand added to the potting mix is also a great idea.
Keep the soil moist not soggy. Set up a watering schedule and stick to it. Make sure that you reach several inches down in the pot when watering the blueberries. If the pots are made of clay, take into account that clay is porous and allows for more evaporation to take place.
Tap water is sufficient if you’ve amended the soil properly. The soil will act as a buffer for the alkalinity in the water. If the tap water in your area is too alkaline, raise soil acidity through amendments every year for a healthy plant population. When temperatures hit the 80s, water the plants every other day.
Don’t forget to add mulch to the pots to prevent water evaporation. Blueberries are shallow rooted and need all the extra protection they can get.
If you plan to grow blueberries in pots give them plenty of space to thrive. Go for the widest pots that you can get, as blueberries roots spread out horizontally not vertically. Plastic pots are ok.
Blueberries love both their soil and food acidic. So, any type of acidic fertilizer will do (look for fertilizers sold for rhododendrons and azaleas). Just make sure that you don’t over-saturate the soil with nitrogen, unless you want bushy plants with little to no fruit.
Also, blueberries love an ammonium form of nitrogen such as ammonium sulfate or urea. Just make sure that the acidic fertilizer you use is fit for edible crops. Also, avoid products that contain heavy metals like mercury, arsenic, or lead.
If you like to keep things organic in your backyard, you can make your own organic fertilizers for blueberries:
- Powdered seaweed and bone meal come will add important nutrients to the soil, such as potassium and phosphorus;
- Fish meal and blood meal are great sources of blueberry-friendly nitrogen;
- Fresh coffee grounds will keep alkalinity in check;
- Apple cider vinegar is an important source of nutrients acid loving plants desperately need such as phosphorus and magnesium, while it keeps soil acidity up.
For a generous crop, use fertilizer and compost on a regular basis.
Blueberries and Iron Chlorosis
If you end up with sickly plants in your pots after a year or two, you might have an iron chlorosis problem, which is just a fancy name for iron deficiency in plants. This condition is caused by the plants’ inability to draw iron from the soil to stay healthy.
The main cause of iron cholorosis is a too alkalinish soil for a plant’s taste. The main telltale sign is yellow leaves with light greenish veins. A blueberry bush with this condition can die within one or two seasons if not helped.
Bring soil acidity back up with an ammonium sulfate treatment (don’t use the chemical when harvesting) and replenish the lost iron with liquid iron. Spray with ammonium sulfate every year if the water is too alkaline in your area. Soil tests are a must when growing blueberries, too.
Related: Testing Your Soil pH Without a Kit
A great prevention measure that ensure there’s plenty of acidity going on in the soil is an apple cider vinegar treatment. Replace the normal water with one cup of unfiltered vinegar (preferably with mother) to 1 gallon of water twice a week if the chlorosis is severe. Use for up to 2 weeks then half the amount of vinegar and continue watering the plant with it.
Don’t use undiluted ACV as it might burn the roots. Also, use only ACV with a maximum strength of 10%. Beyond 5%, use just 1/2 to 2 tablespoons of vinegar per gallon of water. Apply the ACV treatment during the shrubs’ blooming and fruiting season.
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