Herbs are usually hardy, and able to tolerate many kinds of conditions outdoors as long as they are not too extreme, from winters to moderate droughts. But if you have a greenhouse, you might want to grow them in there. There are some herbs that take to the greenhouse environment more readily than others.
Considered the “king of herbs,” basil is commonly used in Italian cooking. Although the common basil (Ocimum basilicum) is an annual, there are perennial types too. They can grow throughout the winter in a greenhouse, either from cuttings or seed. In frost free conditions, and good amount of sunlight, they can grow 1-3 feet high.
There are a number of plants that are called chamomile. One of the chamomiles called Roman Chamomile (Anthemis nobilis) is an excellent choice for greenhouse planting. With its fragrant, bright green scented leaves and delicate white flowers, chamomile has a long history of medicinal and aromatherapy usage. It needs full sun or very light shade, so needs to be near the windows. Water moderately and plant in well drained soil; it grows to 2 feet high.
A perennial, ground cover herb that cats love. If you own cats, you should be planting catnip. About 50% of all cats get a high when they come in contact with bruised/crushed catnip leaves. The Common variety (Nepeta cataria) grows to 2-3 feet high, and grows easily from seed in well drained soil, with dull green leaves, and whitish flowers. The Greek variety (Nepeta parnassica) has pinkish, violet flowers. Catnip oil is also a fine insect repellent, so having a lot of catnip around may work in keeping mosquitoes away.
Relatives of the onion, chives thrive in a greenhouse setting. Chives are said to repel some pests, and so are useful plants to grow. There are many varieties, but they are mostly evergreen and therefore go dormant in harsh winters. But in a greenhouse, they flourish, growing to 2 feet high and propagate easily from divisions or seed. The flowers are purplish and borne in spring. Chives give a delicate onion smell to any dish, if chopped leaves are sprinkled as garnishing.
Parsley (Petroselinum crispum) makes attractive edging for any type of garden. There are curled leaf and flat leaf types of parsley, which all grow to about 2 feet high. The common curled leaf parsley is best grown as an annual in partial shade, though it is also able to take full sunshine. Parsley seeds are known for taking a long time to sprout (up to weeks). Soak the seeds in warm water for a day, before planting. Plant them in healthy soil and water them regularly, but not excessively.
We are referring to cranesbills or true/hardy geraniums here. Herbaceous (non-woody stems that dieback at the end of each growing season); they are exquisite plants with pretty flowers. They are mostly perennial, and range from a couple of inches to a couple of feet tall. Dense and carpet-like, geraniums will grow well under full sun and moderate soil. The dried leaves and flowers emit a delicate scent, and are useful as sachet or potpourri material. The variety of geranium that most people get confused with is pelargonium geraniums, which have attractive flowers, but the true cranesbill geraniums are just as attractive.
Altogether, there are a few hundred varieties of geraniums that usually make good candidates for the greenhouse. A few suggested varieties of geraniums are Geranium clarkei, Geranium grandiflorum, Geranium endressii, Geranium pratense, and Geranium oxonanium.
Greenhouse herbs should be sited around the edge or in the center, wherever there is sufficient sunshine and heat during the day. Most herbs do not like wet soil or too much fertilizer, so don’t overdo them and they will flourish just as well, without needing the same level of supervision as other kinds of plants.