How to Grow Avocados in a Greenhouse: A Step-By-Step Guide


We all love Avocados, and it would be amazing to know just how to grow them independently. Most people have had their luck with growing them in greenhouses successfully, especially in temperate regions than growing them outdoors.

To grow your avocado in a greenhouse, you will have to initially germinate the avocado seen, cut off the tip of the plant shoots, and then plant it in well-drained soil. Move on to graft a scion onto your rootstock, all the while ensuring proper care for the plant. Finally, you will have to cross-pollinate your avocado tree to make it bear fruit.

A much more in-depth and step-by-step process will be covered in the next sections, so read on.

Avocados – an introduction

Avocados fruits grow from trees that are said to have originated from south-central Mexico. Avocados are considered to be large berries containing a large seed at the center of their fruit.

I use color as my chief guide. But I always squeeze an avocado – you want the fruit to feel close to the skin. If you can feel a separation, the avocado is past its prime. The avocado should have a little give, but not much.

Dorie Greenspan

Over the last 20 years, the US has accounted for a 443% increase in consumption of avocados throughout the years, starting from 1.6 pounds back in the 1995s and reaching 7.1 pounds last 2015 (source). This goes to show how much there is a need for more of this fruit.

A Step-By-Step Guide to Growing Avocados in a Greenhouse

There are several steps to ensuring proper growth for avocados, and we will be unpacking them step by step and the needed tips for its growth.

1. Seed Germination of avocados

Germinating avocado seeds is exciting and fun. You get to see the roots and shoot growing from the pit. This is how you can germinate an avocado seed:

Clean the avocado Seed

Soak the seed in water for a few minutes to clean the seed. Make sure that you do not peel out the brown skin. The brown skin is the seed cover, and it protects the embryo from bacteria and fungi.

Locate the Top and Bottom Parts of the avocado Seed

A side of avocado seeds is usually pointed, and their top/bottom sides are easy to recognize. The top is the side that is pointed up, while the bottom is flat.

Before we get right into the detail of how to grow avocado in a polytunnel I made a video showing you how to do it and the many methods. The video along with this article will have you growing them like a pro.

Hang the avocado Seed on a Glass of Water with Toothpicks

Pin three toothpicks at a bottom angle of the seed. Using the toothpicks, hang the pit on a jar of water. The pit should be half-submerged. Always add more freshwater so that the base of the seed will remain submerged.

Within two to eight weeks, you should notice that the seed is splitting, and a tap root has emerged from within. Always add fresh water. You should also notice a shoot growing from the top of the seed.

Eight weeks are enough for avocado seeds to germinate. If you do not notice any sign of growth after eight weeks, try the process with another seed. When your seed has germinated, move on to the next step.

2. Cut Off Half of the Shoot of the avocado plant

When the shoot reaches a height of 30cm, cut 15cm off.

Cutting off the shoot is important because it helps you identify a healthy plant (with established roots) and makes the avocado bushy instead of growing tall.

3. Plant the Avocado in Your Greenhouse

When a new set of leaves have grown, transplant the stalk into a large pot or on your greenhouse soil, the tip of the seed should poke out of the soil. The soil should also be moderately rich and well-drained.

When watering your avocado, always water when the soil is becoming dry. Avocados grown in a greenhouse are not watered as often as those planted outdoors. Do not use inorganic fertilizer and instead opt for peat moss or compost.

4. Graft a Scion onto Your Rootstock of your Avocado plant in the greenhouse

Avocado trees planted from seeds are sterile, which most don’t know. To get a tree that produces fruits, you will need to graft the branch of a propagated tree onto your avocado.

When your avocado shoot is two feet tall, graft a scion (i.e., the branch from the propagated tree) onto it.

The scion should be grafted properly so that water and nutrients can flow from the rootstock (i.e., your plant with already established roots) to the scion.

After six months to a year, or when the roots of your avocado have covered the pot, transplant the young tree into a large pot (which will be its permanent pot). Continue watering as instructed above, and add fresh compost or slow-release manure to the plant.

5. Provide Regular Care to your avocado plant in the greenhouse

How can you care for your Avocado in your greenhouse? Here are some useful tips:

Temperature of the greenhouse is important to check for fostering avocado plants

Avocados are tropical and subtropical trees. To grow and produce fruits, avocado plants need 15°-29°C (60°-85°F).

In temperate places like the UK, the USA, etc., planting avocados in a greenhouse is more advantageous than planting outdoors because a greenhouse traps atmospheric temperature (i.e., the inside of a greenhouse is warmer than the average temperature outside the greenhouse).

Since it is easier to regulate the temperature in a greenhouse, greenhouse avocados survive during winter. Unless you are lucky enough to have a cold-hardy variety, your avocado will not be able to survive winter or frost.

Avocados Love a Humid Greenhouse

The humidity in your greenhouse should always be above 50%. Avocados cannot survive in an environment with less than 40% humidity.

It is more advantageous to grow your avocado in a greenhouse than planting outdoors because greenhouses trap water vapor lost by evaporation or transpiration. The vapor trapped by greenhouses increases the humidity of the room.

If the average humidity in your greenhouse is below 40%, look into installing a humidifier.

Watering Avocados in the greenhouse

Do not overwater your tree. Avocados can get root rot when they are overwatered.

In a greenhouse, water loss by evaporation and transpiration (i.e., water lost from a plant leaf) is reduced. You should water your greenhouse avocado only when the soil is becoming dry and make sure that the soil is well-drained.

How to Get a Bushy Avocado in the greenhouse

Outdoor avocado trees can grow up to 40 feet tall, while their indoor-grown counterparts can reach the height of about 20 feet.

There is a trick that can reduce the height of your avocado tree into a bushy-like plan would be to cut off overgrown branches and leaf petioles.

When a branch is cut off, the plant grows more branches scattered in different directions from that point. This stops your avocado from growing tall and also gives it a bushy appearance.

Fertilizing Your Avocado Tree in the greenhouse

Generally, trees like avocados do not require excess fertilizing since they grow and produce fruits slowly.

Fertilizing your avocado depends on the type of potting mix ratio. If you have more sandy soil, you should add more compost or slow-release fertilizers into the pot.

Earthworm castings are also known to be beneficial to your avocado. If you can, introduce earthworms into the pot as they will hasten the decomposition of your compost while providing your tree with nutritious castings.

6. How to Pollinate Your Avocados in the greenhouse

Avocados are entomophilic plants. This means that insects pollinate them. You can also look into cross-pollinating it with another avocado tree.

Pollinating avocados is complex and confusing for people who are not experienced with avocados or grow avocados in greenhouses. Hopefully, the tips below help you learn about this process more clearly.

Plant More Than One Avocado Tree in your greenhouse

Except if you are growing your avocado in a region where avocados are popularly cultivated, you will need to grow more than one avocado tree if you want your tree to bear fruits.

When there are multiple avocados in an area (in this case, a greenhouse), your trees have better chances of producing fruits.

Consider Introducing Insects to aid in Avocado tree Pollination into your greenhouse

Avocados are entomophilic, so you must either take your plants to anthophilous insects (i.e., insects that pollinate plants) or bring pollinating insects to your plants.

Examples of pollinating insects for avocados would be bees, butterflies, wasps, etc.

To produce more fruits, you can hire bees from a local beekeeper, or you can take your avocados outside when they are flowering.

7. Growing and bearing of fruits period for avocado plants in the greenhouse

Note that avocados can take five to ten years to produce fruits. During the said period, you should add fresh compost into your pot yearly and continue watering as instructed above.

Types of avocados you can consider growing in the greenhouse

The different varieties of Avocados are grouped into two types: Type A and Type B.

Type A avocados open the stigma (i.e., the female part of their flowers) in the morning, then the anther (i.e., the male part of their flowers) later in the afternoon, while in contrast, Type B avocados open their anthers in the morning, then their stigmas later in the afternoon.

The difference between the types of avocados implies that the chance of your plants producing fruits is more when different types are cross-pollinated.

Cross-pollinating different types of avocados is why offspring avocado plants are sterile (i.e., they cannot produce fruits).

Examples of Type A and Type B avocados will be given below:

Type A and Type B Avocado Varieties

The table below shall list the different varieties of Type A and Type B avocados.

Type A VarietiesType B Varieties
HassJoey
ReedBacon
Gwen Fuerte
HolidayZutano
StewartSir Prize
PintertonBrogdon
Lamb HassWinter Mexican  
Carmen HassWilma (aka Brazos Belle)
Opal (aka Lilas)
Mexicola Grande
Pryor (aka Fantastic)

We will also be introducing cold-hardy varieties that can be grown in temperate regions in the next section.

Cold-Hardy Avocado Varieties

The table below contains avocado breeds, their type, and the least temperatures they can tolerate. When growing your avocado tree, it is best to grow the trees in warmer temperatures.

NAMETYPETOLERABLE TEMPERATURE
BaconB-7° to -6°C (20°-22°F)
BrogdonB-4°C (24°F)
FantasticA-9°C (15°F)
FuerteB-1°C (30°F)
JoeyB-9° to -8°C (15-18°F)
Mexicola GrandeA-8° to -7°C (18-20°F)
OpalA-6° to -4°C (22-25°F)
WilmaB-9° to -8°C (15-18°F)
Winter MexicanB-6° to -4°C (22-25°F)

There should be more than enough avocado types that you can look into growing and fostering in your greenhouses with the lists above.

Benefits of eating avocado fruit

It is widely loved because it is rich in nutrients and has beneficial fats that are good for managing and lowering cholesterol levels.

They are also known to aid in good digestion, level blood pressure due to their potassium content and contains about 41% of the daily needed folate intake to help prevent congenital disabilities during pregnancy (source).

Avocados are rather difficult to grow outdoors, so most people opt to foster them within greenhouses. The next section shall cover the step-by-step process of doing that.

FAQs

Conclusion on how to grow Avocados in greenhouses

Avocado fruits have many great benefits for health and taste good, making them a very sought-after fruit. Due to this peak in demand, countries like the US have also been importing about 80% of these fruits worldwide to meet consumer needs (source).

With you being an aspiring gardener, instead of buying them, hopefully with this information and tips, you can now look into growing them yourselves in your greenhouses and be proud that you were there every step of the way in its growth process.

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Tony O'Neill

I am Tony O'Neill, A full-time firefighter, and professional gardener. I have spent most of my life gardening. From the age of 7 until the present day at 46. My goal is to use my love and knowledge of gardening to support you and to simplify the gardening process so you are more productive

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