Hydroponic Flowering Annuals and House Plants

By Lynette Morgan
Published: October 13, 2022 | Last updated: October 13, 2022 06:10:37
Key Takeaways

A beautiful display of blooms or a mixed floral border can make an indoor garden and hydroponic system into a truly magnificent sight, especially during those dark and dreary winter months.

While many of us focus on fruit, veggies, and herbs, hydroponics allows for such a diverse range of species that incorporating a little color can really add a touch of extravagance to a mixed planting. Flowering annuals are rapid-growing, colorful plants, often used to fill outdoor border gardens and patio pots. However, they make great hydroponic specimens with the advantage of being very quick to propagate and flower. There is also a huge range of species commonly grown as flowering annuals and many have dual uses such as edible flowers or providing a heady scent in the garden and as cut blooms. Flowering house plants are another category which can add a pop of color to an indoor space and with the advanced lighting and nutrition provided in hydroponics, the range of species which can be grown as house plants is extensive and often surprising.


Flowering Annuals

Sunflowers are annuals which love the plentiful moisture and nutrients of hydroponic systems.Sunflowers are annuals which love the plentiful moisture and nutrients of hydroponic systems.
Flowering annuals include a wide range of species with endless choices in plant and flower form, color, scent, and growth rate. Modern breeding has seen significant improvements in all aspects of these plants, with many dwarf, compact, and disease-resistant options available for many. Flowering annuals are typically propagated from seed, however, seedlings can also be purchased and adapted to hydroponic systems, with many flowering within a few short weeks. The main advantage of a mass display of flowering annuals, apart from fast growth and rapid flowering, is that displays that can be changed regularly and most are easily interplanted with other hydroponic crops.

Selections of flowering annual species suited to a hydroponic display can be daunting as seed catalogues are crammed with colorful images and spectacular offerings. The main factors to consider is flower timing, height, and spread of each species. If planting an indoor border garden within a hydroponic system, choosing taller species to be planted towards the back and smaller, or trailing plants, for the front with give the most eye-catching display and allow the blooms of each plant to be easily seen. Seed supplies usually state the time to flowering for each annual species so a hydroponic display can be timed for maximum visual effect. Suitable taller annuals include snapdragons, stocks, cornflowers, zinnias, and inpatients while more compact and trailing plants for the front of a display include pansies, violas, petunias, lobelia, and nasturtiums. Taller-growing annuals may require some basic plant support like stakes or flower netting, particularly if the objective is to produce some cut blooms with long straight stems. Restricting plantings to only the short and compact annuals is another way of keeping plants in check without the need to support plants as they develop.

Some larger flowering annuals can be grown as specimen plants, either individually or in small groups. These include the ever-popular sunflower, which with a high water and nutrient requirement is well suited to hydroponic conditions. Sunflower cultivars come in a range of colors and heights with compact dwarf varieties only growing to 12-36 inches, making them ideal for pots and hydroponic systems. Colors of sunflower now include not only the traditional yellow, but also red, orange, white, cream, brown, and bicolored. Sunflowers are also a popular cut flower species and can be grown for profit hydroponically.

Flowering House Plants

Dwarf potted chrysanthemums can be used as flowering houseplants when in bloom.Dwarf potted chrysanthemums can be used as flowering houseplants when in bloom.
Flowering house plants fall into two categories: those which are more traditional indoor plants and can be grown long term — including well-known species such as begonias, African violets, cyclamen, kalanchoe, peace lily, gerbera, streptocarpus, and anthurium, and the more temporary houseplants, which are brought into the growing area as they start to bloom and complete the dormant stage of their life cycle outdoors. These include many flowering bulbs that can also be forced to flower out of season. Garden and greenhouse plants such as dianthus, fuchsia, primula, chrysanthemum, and miniature roses are commonly utilized as flowering house plants for part of the year when in bloom and all thrive under hydroponic cultivation.

Many of these types of plants are easily grown from stem cuttings or purchased as young cell plants and will flower easily. Some, like chrysanthemums, may have day-length requirements for flowering so some research into each flowering species is always a good place to start.

A popular flowering houseplant option includes bulbs, which are readily available to purchase during their dormant season and relatively inexpensive. Many bulbs require some form of dormancy, usually chilling as would be experienced outdoors, and this can be replicated in a refrigerator before being planted out into a hydroponic system. Once exposed to warmth and moisture, bulbs spring to life and most bloom relatively quickly within a few weeks. Popular bulbs for indoor displays include freesias, hyacinth, tulips, iris, daffodils, and crocus, while hydroponic beds of mixed bulb species can provide for many weeks of color.



Hydroponic Systems

Bulbs such as iris and freesias make great indoor flowering specimens.Bulbs such as iris and freesias make great indoor flowering specimens.
Flowering annuals and houseplants can be grown in a diverse range of hydroponic systems, from NFT, DFT, aeroponics, ebb and flow, and drip-irrigated substrates. Care needs to be taken with some moisture-sensitive species such as African violets and flowering succulents/cacti, which prefer a drier medium and are more suited to capillary or hand watering. Since most smaller annuals are only grown for a fairly limited period, the root systems can be contained in NFT or aeroponics. Annuals and flowering houseplants can also be grown in more traditional ceramic or terracotta pots within an indoor garden using soilless substrates such as coconut fiber or perlite, and can be drip-fed or hand-watered hydroponic nutrients as required.

Flowering annuals and houseplants perform extremely well under hydroponic nutrition and general-purpose nutrient formulations, and an EC of 1.4–1.6 is suitable for most species. Once in bloom these plants do benefit from use of a ‘bloom’ formulation to provide additional potassium, as flowering annuals in particular produce a rapid profusion of blooms over a short time frame and can be relatively heavy feeders under good growing conditions.

Propagation and Obtaining Plants

Short, compact flowering plants such as dianthus are ideal to interplant with other species in a hydroponic system.Short, compact flowering plants such as dianthus are ideal to interplant with other species in a hydroponic system.
Flowering annuals can be easily and quickly raised by seed that usually germinates readily, while slower species can be purchased as young cell plants that are suitable to plant into substrate hydroponic systems for an even quicker display of flowers. Flowering houseplants can be propagated in several different ways depending on the species. Some, such as cyclamen, primula, certain begonia species, and dianthus can be raised from seed, while others are grown from cuttings (clones). Others, such as orchids, may require specialized propagation via tissue culture and other methods and are best purchased as young plants.

Multiplying flowering houseplants is one area of potential profit for small-scale indoor and greenhouse growers as these plants are not only growing in popularity but also need a protected environment for propagation and early growth. Researching the different types of propagation is always advisable as there are a range of methods used for these species including stem, leaf, petiole or root cuttings, division and air layering, and a number of ways in which the changes of successes can be increased. Hydroponic environments that control temperature, humidity, and light are a great advantage, along with use of propagation products such as hormone gels and heated cloning units.

Flowering annuals are a great category of easy-to-grow plants for those new to hydroponics, who want a burst of color for minimal effort, or for those who crave the flowers of spring during the depths of winter. Flowering houseplants, either long-term or as a short-term indoor display, are another option, with hydroponics providing advanced nutrition and growing conditions that often results in some truly magnificent blooms.


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Written by Lynette Morgan | Author, Partner at SUNTEC International Hydroponic Consultants

Profile Picture of Lynette Morgan

Dr. Lynette Morgan holds a B. Hort. Tech. degree and a PhD in hydroponic greenhouse production from Massey University, New Zealand. A partner with SUNTEC International Hydroponic Consultants, Lynette is involved in remote and on-site consultancy services for new and existing commercial greenhouse growers worldwide as well as research trials and product development for manufacturers of hydroponic products. Lynette has authored five hydroponic technical books and is working on her sixth.

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