Friday, April 23, 2010

How to: Grow Avocado from seed

The avocado (Persea americana) is one of the more popularly cultivated tropical plants. A common name for this fruit is the Alligator Pear, named in part to its rough skin and pear shape. Its native to the Americas and has a wide variety of culinary uses especially in dips and sandwiches. The trees do best outside (in tropical/sub-tropical climates) where they will grow tall and fruit abundantly. The best areas for the cultivation of avocados are zones 9-11+. If you can protect your avocado from frost then growing in a lower zone may be possible. The best places to grow Avocado in the United States are California, Florida, and the lower states. If you are buying a live avocado tree, be sure to check it's hardiness; be certain that you can provide a warm enough environment for it. For those of you living in colder climates you can still grow avocados inside your house or in a greenhouse, although in these situations it will be unlikely that you get any fruit. When young the plant looks like a typical house plant, similar to a money tree (Pachira aquatica).

Next time you are making guacamole think twice about throwing away the pits. Have some fun with them, try growing them in water. This method is easy, fun, and rewarding, if you have a little patience. You will need three toothpicks, a small cup, and an avocado pit. First place your seed(s) in a glass of hot water (120-130F) to kill any possible avocado root rot pathogens. Place your avocado pit pointy side up and gently push in the toothpicks equidistant from each other just less than an inch from the tip. Now make sure you can suspend your pit on the rim of the cup. Fill the cup with water and put it just about anywhere that won't get too cold. Change the water often (1-2 times a week) to keep the necessary oxygen levels so that the roots can breathe and to prevent stagnation. Time for germination is anywhere from 3-6 weeks (or more) so this is where a good patience is needed. I have noticed that the warmer it is the faster they germinate so try to maintain a temperature range of 60-85F. I have had a 100% germination rate with my avocado seeds so they seem to be one of the more viable kinds of seeds out there. To improve chances of germination further be sure to plant soon after eating the fruit.

If you are serious about growing an avocado tree, plant your sprouted pit in a moist and well draining soil. You can skip the toothpick method and just plant the seed directly in soil which works great too, just isn't as fun. They do the best in somewhat sandy soils but most generic potting soils work well too. Make sure the soil and container have adequate drainage, poor drainage is lethal for avocados. The soil's Ph should be around 6 but don't worry too much about the Ph. Growing store bought avocado seeds doesn't always produce a true to type plant. This means that if you eat and plant a Hass avocado seed the result could be a tree that produces no flowers/fruit or bears fruits with a poor flavor, unlike that of the fruit which the seed came from. If you are worried about this being the case, don't hesitate from growing those avocado pits anyways, you can still use them as rootstocks. This means that you cut off the entire plant at the stem/trunk and graft on a branch from a productive avocado. Being so, the grafted growth will contain the exact same DNA as the parent of the graft resulting in a clone of the parent tree.

Each avocado variety has it's pros and cons so do some research. Some can take the cold a little better while some produce bigger fruit or different colored fruits. Some of the most popular varieties of commercially grown avocados are Hass, Reed, and Bacon. For serious avocado growers, you can mix and match rootstocks and grafts. For instance some people pick out a variety of avocado that does great in their soil conditions or is especially disease resistant for the rootstock and then find a heavy producing plant to graft onto the rootstock. This results in a specialized avocado tree that suits the growers' soil conditions and climate while producing the kinds of fruits that they love.

These two avocados were grown using the toothpick method. Every day I would check on them to see if anything new happened, but every day they were still just avocado pits in water. Just as I was about to throw them away I noticed that a thick taproot was coming out of both seeds. Growth was still slow though, I blame the cold winter months. I started them just about 6 months ago and they are already over a foot tall! All of the avocado seeds I have planted since have come along a lot faster, or so it seems. These avocados are taller than the ones I grew outside, this is because they received less light next to a window compared to outside in direct sun, and naturally grew up towards the sun. For these taller avocados (and all young trees for that matter) you should gently shake or tap the stem. This acts as an artificial wind. With this movement the plant releases chemicals that signal for the plant to reinforce its stem.



Further tips for growing Avocado trees:
  • Be sure that the soil is very well draining, soggy soils are deadly.
  • Keep on the lookout for avocado diseases, these can strike at a moment's notice.
  • Protect from severe heat by planting in partial shade or under a larger tree.
  • Protect from cold temperatures (Keep in mind an Avocado's hardiness varies by variety).
  • It may take up to 10 years or more before an avocado will bear fruit, so be patient.
  • Fertilize younger plants (Over one year old) with a high phosphorous fertilizer, while mature fruiting/flowering avocados should be given a high nitrogen fertilizer.
  • Use fertilizer sparingly, avocados are sensitive to over fertilization.

Saturday, April 10, 2010

Stevia rebaudiana

Stevia rebaudiana is a member of the Stevia genus consisting of American herbs and shrubs. This specific herb, commonly called Sweetleaf, is indigenous to Paraguay and has an amazing secret, it tastes extremely sweet. What could make this plant any more magical? Its sweet taste isn't created by conventional sugars, instead by a chemical named Stevioside found within the plant. The result is a sugar-free natural sweetener.

Stevia is a popular sweetener and is used in a variety of methods. Commercially the sweet compounds are extracted and sold in liquids or solids for use in food. Stevia leaves can be dried and brewed into a sweet tea or added to other teas to make them sweeter. People often sweeten their morning coffee with a powdered or liquid extract of Stevia. These extracts can be purchased at a local grocery store and are often preferred over the leaves because the extracts dissolve completely as opposed to the leaves which will be left floating around in your drink.

Growing Stevia from seed is very difficult, this is due to Stevia's low germination rate. Not only are the seeds hard to get growing, they are hard to find. If you are lucky enough to buy seeds make sure they are fresh and get at least a few hundred or more. This may seem like a lot but the seeds are very small and with such a low germination rate you will need quantity and a bit of luck. A much easier way to get a hold of some Stevia plants is at your local nursery. While most nurseries carry Stevia make sure you taste it before you buy it. Due to an endless combination of reasons (Soil, Ph, Temperatures, Genetics, ect.) Stevia can be very bitter so pick out the one that tastes the best to ensure you are getting a good quality plant.

Planting Stevia:
This plant does good in pots or planted in the ground, but keep mind of temperatures. If you plant Stevia in a pot you can leave it outside in a garden or backyard and bring it in during the winter. It is known to die back during the winter (if it is outside) but it is likely that it will resurrect during the spring so long as it didn't get too cold. I wouldn't subject this plant to anything under 32°F so it is probably best suited for outdoor cultivation at climate zones 9-11.

How to care for Stevia:
Be alert and check your Stevia frequently for flower buds. Make sure to pinch off all of these flower buds to increase the longevity of your plant as well as enhance the flavor of the leaves. When a Stevia plant goes to flower the leaves become more bitter and are far less enjoyable. Don't be afraid to take a daily snack on your plant either. By trimming up the plant it will be forced to focus on further leaf production as opposed to flowers, plus the new leaves taste the best. Be sure not to water too much, if you notice that the soil is soggy don't water it more. Water logging can easily kill a Stevia plant, especially when indoors where moisture is retained better. Also be sure your Stevia has sufficient light, part shade or full sun, if you plant inside make sure it is near a south facing window to get the maximum amount of light.

Government regulation of Stevia:
Due to Government concern about Stevia's safety it is regulated and even banned in some places, most notably the European Union. Most of the skepticism surrounding this plant is due to its relatively recent discovery and limited research on its safety for consumption. No real evidence suggesting harmful effects on humans has been documented and the sweet compounds in Stevia are "Generally recognized as safe" for consumption by the USDA.

Update: Stevia is no longer banned by the European Union.

Friday, April 2, 2010

Passiflora Edulis

Passionfruits belong to the Passiflora genus with hundreds of species. While Passiflora can be found around the world, the most common for eating is the Passiflora edulis species that is native to South America. This species is not frost tolerant which means that the main areas of cultivation are tropical or sub-tropical climates. I have heard of this species doing very well in Hawaii, Florida, and parts of California. Where can you get passionfruit vines? You can either grow them yourself by seed, propagate from a parent plant, or buy a live plant.

This passionflower (Passiflora edulis) is a great example of the beauty behind these wonderful plants. The passionflower is an exquisite and complex flower consisting of 10 petals, many radial filaments, a centric ovary, 3 stigmas and 5 anthers. This alien flower seems to have a mathematical aspect to its design, a very bizarre specimen and one of my favorite flowers.

How to eat a passionfruit:
The most important thing about eating passionfruits is knowing the exact species from which the fruit comes. Not all passionfruits are edible so be careful about eating fruits found in the wild. If you find the fruits in the grocery store, they are safe to eat, but be weary of buying Passiflora plants on the internet or at nurseries. If the information given to you doesn't specify the edibility of that species you should refer to the internet. In addition unripe fruits of certain edible species should not be consumed by humans. The fruits of P. edulis are typically purple fleshed with yellow pulp, eat the pulp and discard the skin. Don't be afraid of the seeds, they are edible too; I think of them as larger versions of kiwi seeds. There is a wide variety of culinary uses for passionfruit but its mostly used in desserts such as sorbet. I find the taste to be sweet and tangy but the flavor will vary from each species and variety.

Growing passionfruit by seed:
This option is less favorable for anyone new to passionfruit; This is because Passiflora seeds have long and irregular germination periods. I would estimate germination to occur anywhere from 1 month to 1 year after sowing. There are countless factors effecting the germination period but most prevalent seems to be the freshness of the seeds. For this reason sow your passionflower seeds as soon as possible after collecting. The advantage to growing passionfruit by seed is their extraordinary potential for hybridization. Hybridizing two different varieties of passionfruit can lead to some truly spectacular flowers.

Tips to growing passionfruit:
Make sure you have a soil that is well draining and rich in potassium. If the conditions are favorable passionfruit vines will take over! If in a greenhouse be sure to tame the growth of this exploratory plant by pruning the long stems. A trellis or support stake are needed to control the growth of this plant and to provide orderly growth.

Pests and problems cultivating:
I would consider caterpillars and snails as the biggest pests of passionfruit but I have yet to have problems with either. However I have had problems with yellowing leaves and this is most likely due to an iron or sulfur deficiency, and is an easy fix with appropriate application of these nutrients. Overwintering is one of the biggest obstacles for many passionfruit growers but there are many ways to combat this issue. One of the easiest is to put it in a greenhouse. For those who wish to grow this plant outside be sure to choose a cold hardy species that suits your climate zone. There are some species of Passionflower that can survive below freezing temperatures although such temperatures are fatal for most commercially grown edible plants.

This is a Crimson Passionflower (Passiflora vitifolia). It's supposedly an edible species native to Central and South America. It provides a good contrast to P. edulis, as its petals are a vibrant red and elongated with a wider leaf structure. As well, this species' radial filaments are much shorter than those of the P. edulis. There are huge differences between each species of passionfruit and there are some truly crazy ones out there. In addition hybridization creates an endless variety of flowers.