How to Start Your Blueberry Patch
It's all about the roots. It is necessary to get this right because you have only one shot at it. Blueberry shrubs may produce for 20 years, but you can only prepare their home once, before you plant (but if I already brought one home from the store, what do I do now?). It is just as difficult to fix the soil after you plant as it is to replace the lot after the house is built. If the shrub is not comfortable it will not produce its normal yield of quality fruit no matter how many magic potions you pour onto the soil, and in a poor environment the plant will slowly wither away and you'll have wasted all that time, effort and money.
Fortunately, it is easy to provide blueberries with a fine foundation. Mother Nature has been doing it for years without anyone coming along to help. In your garden it may take a little work and some soil amending, but the payoff is years and years of fruit where the only labor will be picking and easy pruning.
Size-wise, give each plant two or three feet of room all around it. Add space for harvesting. They will grow to be five to six feet tall. Blueberry plants make a great hedge with gorgeous autumn colors; they drop their leaves during winter.
Soil Preparation Most Important
This is definitely the critical factor. In a nutshell, blueberries would like to grow in a damp sponge laying mostly on top of the ground, and some growers actually do it that way if their soil is very heavy or wet, see a few paragraphs down. Also see Improving Your Garden Soil if you suspect you have poor, worn-out soil. Blueberry roots like a medium containing microbial life. Brand new soils don't have that. It would have been ideal if you had prepared the planting area last year, but don't let that stop you. If you received a small mail-order plant, it'll be just the right size to put in a gallon pot and hold over until next year.
Choose a site in sun or part shade with a minimum of a half day of sunshine, and within reach of your hose or watering system. Blueberries absolutely have to have water during the growing season, sometimes twice a week, and you're not going to want to be dragging heavy hoses around (soaker hoses under the mulch are awesome.) But do not plant them in soil that stays wet. Contrary to popular belief, blueberries do not do well in wet soils. If wet soil is all you have, provide a mound or plant them in a raised bed. The plants will die if the roots can't breathe. The green leaves use sunlight to make sugar and send it to the roots, where it is converted into energy to run the plant's motor. And just like you and me, during that process the roots inhale oxygen and give off carbon dioxide. There have to be air spaces in the soil for that. Provide blueberry shrubs with some sun, water and drainage, and you're golden.
Blueberry roots prefer an acid and spongy organic medium that is constantly breaking down, similar to that layer of soil you find in the woods directly under the leaf litter. Some varieties of blueberries are fussy about this requirement and others don't really care all that much, but production will be much higher and fruit will taste better and be healthier if the soil is of the proper type. And just like in the forest, that small round plot of soil will soon be colonized by hundreds of thousands of microbes and fungi and protozoa. That's desirable because the blueberry roots rely on their help to get the food out of the ground. Keep those little guys healthy by going easy on the aggressive chemicals and fertilizers.
Blueberry roots grow horizontally, so prepare wide and shallow holes. What size hole do you make? Three feet across would be good, four feet better. The depth should be 18 to 20 inches. Mix the soil you took out of the hole with up to an equal amount of soaked peat moss (best since it is acidic) or coco fiber or fir bark (not redwood bark, it does not break down well), or compost or soil amendment. Add sulfur (see below) if you don't use peat moss. All these are available at the garden centers. Why so much amendment? Blueberry shrubs like their soil to be in a constantly-breaking-down condition, and you can only provide that in a soil with a high organic content.
Do not use spent growers soil and do not use mushroom soil. These items are often free for the hauling and may look like they will be useful, but they are contaminated with fertilizer salts and will be toxic to blueberries. Salts and acidity are not the same.
Quite a few blueberry growers dig holes only a foot deep, then use acidic materials to fill it and build a raised mound (there's that sponge) that may be as much as a foot above ground. That's a terrific idea if your winters are extremely wet, or if you soil is heavy and compact and does not drain all that well. Blueberries do not appreciate being planted in a bathtub, they evolved to grow on the top layer of soil, and it's wise to give them what they want. Raised areas do dry out faster, so pile on the mulch. That'll also help keep the weeds down.
If your soil has a high pH (not real likely here on California's North Coast), you would want to add an acidifying component such as elemental sulfur, on the right, the same stuff that makes some hydrangea flowers turn blue. How much? You should do a pH test because soils vary. A blueberry shrub's comfort level is at a pH of 4.5 to 5.5 and a reading too far away from this range in either direction will be detrimental. Bacteria in the soil will convert the granular sulfur to sulfuric acid, acidifying the soil, but so slowly that you will not see different test results until next season. Don't use more than a quarter pound per plant, and mix it in well. Two cautions here, don't use aluminum sulfate, aluminum is toxic to blueberries. Second, sulfur and constantly wet soil do not go well together because the anaerobic bacteria in oxygen-poor soil will instead convert the sulfur to hydrogen sulfide (that rotten-egg smell), which weakens and destroys the blueberry roots. But that may not become an issue; the blueberry shrubs would likely already be strangling in that environment due to root suffocation. Blueberry roots need to breathe.
So how about if you just plant the thing for now and then put the peat moss and a pile of organic matter on top of the soil and let it work its way into the soil? It doesn't work that way. It will take years to benefit the roots, if ever. By then your plant will be stunted and weakened and it'll all be a big waste. Do it right, kick back and reap 20 years of harvest. You'll be amazed with the results and will be giving away berries to the grandkids and the neighbors. Maybe. Some of our best-tasting berries don't even make it into the house...
Can't plant right away? See further down for an alternative.
Make sure the soil underneath the root ball is firm and well-tamped to prevent the plant from sinking, and set the plant in the soil at the same depth or higher than it was in the pot. Water well and mulch with at least two inches of pine needles or oak leaves. Why pine needles or oak leaves? They're acidic and will keep your soil conditions right as they decompose. Where does one get pine needles? Look for a brown carpet in the street gutters under trees with cones and long skinny needles, bring a garbage can and something to pick them up with. Ask your Street Department (the street sweeper picks them up) or the Parks Department, they may have a pile of them somewhere. Drive down back roads, look for that brown carpet under trees with cones and long needles. Take a small amount here and there, nature doesn't mind sharing, don't trespass.
Oops, one more thing. You're going to need to remember the name and time of harvest of the varieties you planted so you don't duplicate them later. Most blueberry shrubs will provide you with fruit for about two weeks. They ripen in early, mid or late harvest periods, and you will want to spread out the harvest. Don't end up with three plants that ripen all their fruit within the same period, mix them up and extend it. Enter it into your database, write it in your gardening journal, on the inside garage wall, scratch it into the sidewalk, whatever you need to do, but make a permanent record, especially of the one you like so much. Plant tags self-destruct after a year. Ink fades, even from permanent markers. Metal tags get lost. Minds get fuzzy. Make a permanent record that will last 20 years.
No. Not while planting. Wait until next year. Blueberry plants do not grow much the first year and adding fertilizer is not going to make them grow any faster. Not only did blueberries evolve to use very little fertilizer, some fertilizers are even toxic to blueberry shrubs. See the next article.
But I Just Brought the Plant Home. Can't I Just Put it in a Pot?
What to do when you visit the nursery and find just the blueberry you've been looking for, but there's no way you can get a planting spot ready for it until next year? A blueberry plant will keep just fine—AND give you a limited crop of fruit at the same time—if it is planted in a 10 or 15 gallon low pot. These containers are typically 17" wide and 12-15" high. Blueberry roots prefer to grow mostly horizontally, not so much down, so it would not be good practice to plant them in a tall, skinny container. Place 1½ cubic feet of acid potting soil (ask for it at the garden center) in the pot and there will be room for a mulch.
Place the plant in a mostly sunny area, but if the sun heats the pot too much, put it where it gets afternoon shade. Lift it up off the patio slab to keep the bottom from cooking, and add a mulch to keep the top cool. Water, water, water, don't forget to water, at least every other day. If water immediately runs out the drain holes, you're not watering often enough. Next year lift the mulch and apply a small amount of fertilizer when the leaves appear in early spring and again when the berries are forming. The shrub will be fine for a year or two, but move it into its permanent home before it gets too unwieldy. Even in a pot it will try to get five feet tall.
Planting them permanently in a big container? Half barrels are real good, and they usually last about the length of the blueberry's life. Don't forget to make at least five drain holes in the bottom, a three-quarter or one-inch drill bit would be good. Leave the holes uncovered on the inside and check the outside to make sure they drain properly. Don't put drain rocks in the bottom, those cause a perched water table. Create your soil by mixing one third small fir bark (not redwood, it doesn't break down, not cedar either), one third coarse peat moss and one third good potting soil based on forest products. Alternatively, obtain a good acid soil mix from the nursery, or mix a good potting soil with the same amount of moistened peat moss. Even blueberry shrubs in containers will grow to be as high as you, so pick out blueberry cultivars that remain smaller and will tolerate confined roots (the Sunshine Blue variety is a good container blueberry plant, Patriot is another). Don't forget their mulch, and be sure to water at least three times a week during the growing season. Containers MUST have drain holes that will not plug up. Your blueberry shrub's roots will die if they can't breathe.
There may be a tag on your plant that says "Propagation Prohibited", but that warning message is meant for those who do so for commercial sales, not for an individual gardener. It'll save you a lot of work and time if you spend the eight bucks for a gallon-size plant that's ready to go into the ground. But if you have a variety that you would like to have more of and you can't find it in the nursery, take cuttings in early spring. Cut sections about pencil length, take off the buds and all but a few leaves on the top (if it doesn't have leaves, cut the top at a slant you'll know which end goes up.) Place the bottom half in an airy rooting medium and keep the cuttings shaded and warm. We have used a mixture of peat moss and tiny bark chips, but a light seed compost from the garden center works, as would perlite. After a couple of months gradually begin exposing the little plants to the sun, and pot them up when they form a good root system. Move them into a gallon pot the following year, and they should be ready to plant in the ground the year after that.