Everyone loves blueberries – they are America’s #2 berry (after strawberries) – and we just love them in muffins and pancakes, in pies and smoothies, scattered over cereal or just popped straight into our mouths. Wouldn’t it be great to grow your own, so you have them fresh and ripened on the bush, and know exactly how they have been grown? This are easy enough if you have suitable soil, and the best varieties are heavy-croppers, giving 8 or 10 pounds of berries from as single bush, once it is well-established.
Blueberries Need Acid Soil
The problem is that these bushes need very acidic soil, with a pH value of 5.0 or less. Unlike some other acid-loving plants that can cope with neutral soils, blueberries really won’t do well at all if they don’t have that highly-acidic soil they need. It is easy to test your soil at home, with a simple kit or a soil probe, but what to do if your soil doesn’t meet the exacting standards blueberry bushes demand? You might read about methods that claim to turn garden soil more acidic, but I can tell you that they usually don’t work, take a lot of effort, and even if they give the results you want for a year or two, they never seem to last very long, and the pH starts rising again.
Growing in Pots is the Answer
So save yourself a lot of futile effort, and do what smart gardeners everywhere are doing – plant your blueberries in pots or boxes filled with suitable soil. It’s an easy solution if your garden soil is too alkaline, and luckily the relatively small and fibrous root system of blueberry bushes is ideal for pot-growing. Your bushes will thrive for years and give you big harvests with a little care.
Choosing Suitable Containers
You can use a variety of containers for blueberries, but the basic need is for drainage. The planters you use must have good drainage, so if necessary drill some extra holes in the bottom. It is best to raise the pot a little off the ground, both on a hard surface and on soil. On a hard surface the excess water may not flow away freely, and on soil there are two potential problems. Alkaline water can rise upwards into the pot, and roots can grow through into the soil, exposing the plants to the wrong soil conditions.
Depending on the mature size of the bush you are growing, you might need planters up to 2 feet deep and wide, but smaller varieties will grow in smaller pots. Don’t put a young plant straight into its final pot – start with smaller pots and re-pot each spring as your bush grows. If you don’t need big crops there are some great new dwarf varieties available that will grow in much smaller pots, and look great on a terrace.
The Right Soil is the Most Important Thing
Since you are using pots to get suitable soil, this is the thing that you need to focus on most. The soil mixes sold for azaleas and camellias are acidic, but rarely enough for blueberries. Still, they are a good place to start. Still, they are a good place to start. You will also need some sphagnum peat moss. That’s the kind often sold compressed in square packs, and sometimes called ‘Canadian’. As well, shredded pine bark is very useful, both in your soil-mix and as mulch. You can often find it sold as mulch for garden beds. Make sure it’s pure bark, not wood chips. If you mix these three things – lime-free potting soil; sphagnum peat; shredded pine bark – in equal parts you will have a mix that drains well but hold moisture, and that should have a pH close to or below 5.0.
Watering Your Bushes
Besides suitable soil, blueberries need plenty of water, and they aren’t drought resistant. But when you water a lot you are also adding the minerals from the water, and if your soil is alkaline, chances are your tap water is too. If you can, rainwater is best, even if you don’t have enough to use it 100%, whatever you can do helps. A barrel beneath a down-pipe will collect a lot of water. Some enthusiasts use de-ionizers, and that’s great if you want to go to that much trouble. Don’t make the mistake of using water that has passed through a softener. It might be acidic, but it is also full of salts that can cause a lot of harm to your bushes.
Water regularly, letting the soil dry just a little on top between each watering, and always water so that a good amount flows out of the drain holes.
Place your pots in a sunny spot – blueberries like the sun. They need at least 6 hours of direct sun each day, and more is better.
Plants in pots are more exposed to cold than when planted in the ground. Blueberries come in many different kinds, with big differences in winter hardiness. As a rough guide, add two extra growing zones when choosing plants for your pots, if they are going to be outdoors all winter. In other words, if you live in zone 5, then you should plant varieties that are hardy to zone 3, and so on. You might be able to add just one zone if you wrap your pots in garden fleece for the winter. Obviously in colder zones you won’t be able to do this, and some shelter is needed. Planting the pot right in the ground will work, but there is a danger that alkaline water will seep into the planters during that time, spoiling all your efforts to keep the soil acidic.
Since blueberries are deciduous, a better solution is to put the pots into a cold shed or similar place. It doesn’t need light, but it should be as cold as possible, as blueberries need winter chill. Bring them back outside as soon as the worst weather is over – you don’t want them to start sprouting in the dark.
Suitable Blueberry Varieties for Pots
With the growing interest in home growing, breeders have been working to create smaller varieties of blueberries that will grow well in pots. Top of the list if you don’t need huge harvests is the Bushel & Berry® range, that features lots of dwarf blueberries for both warm and cold zones. Jelly Bean is a great variety for cooler zones, while Blueberry Buckle is great even in zone 10, and is an attractive bush as well as carrying an early crop. Perpetua is what it sounds like – a unique blueberry that has both a summer and a fall crop.
For larger crops on compact bushes, that will need bigger pots in time, the big favorite is Bluecrop, while Chipewa is another reliable variety that doesn’t grow too large. Both of these are cold resistant, which means the pots can stay outside all year if you are in zone 5 or warmer.